Chitika

SURGERY FILE

Thursday, January 19, 2012

HERNIAS


Introduction

An external hernia is an abnormal protrusion of intra-abdominal tissue through a fascial defect in the abdominal wall. Although the majority of hernias (75%) occurs in the groin, incisional hernias represent an increasing proportion (15–20%), with umbilical and other ventral hernias comprising the remainder. Generally, a hernial mass is composed of covering tissues (skin, subcutaneous tissues, etc), a peritoneal sac, and any contained viscera. Particularly if the neck of the sac is narrow where it emerges from the abdomen, bowel protruding into the hernia may become obstructed or strangulated. If the hernia is not repaired early, the defect may enlarge and operative repair may become more complicated. The definitive treatment of hernia is operative repair.

A reducible hernia is one in which the contents of the sac return to the abdomen spontaneously or with manual pressure when the patient is recumbent.

An irreducible (incarcerated) hernia is one whose contents cannot be returned to the abdomen, usually because they are trapped by a narrow neck. The term "incarceration" does not imply obstruction, inflammation, or ischemia of the herniated organs, though incarceration is necessary for obstruction or strangulation to occur.

Though the lumen of a segment of bowel within the hernia sac may become obstructed, there may initially be no interference with blood supply. Compromise to the blood supply of the contents of the sac (eg, omentum or intestine) results in a strangulated hernia, in which gangrene of the contents of the sac has occurred. The incidence of strangulation is higher in femoral than in inguinal hernias, but strangulation may occur in other hernias as well.

An uncommon and dangerous type of hernia, a Richter hernia, occurs when only part of the circumference of the bowel becomes incarcerated or strangulated in the fascial defect. A strangulated Richter hernia may spontaneously reduce and the gangrenous piece of intestine be overlooked at operation. The bowel may subsequently perforate, with resultant peritonitis.
Etiology

Inguinal hernias may be considered congenital or acquired diseases. Although there is debate, in all likelihood, inguinal hernias in the adult are acquired defects in the abdominal wall. A number of studies have attempted to delineate the precise causes of inguinal hernia formation; however, the risk factors are likely multifactorial, the common denominator being a weakness in the abdominal wall musculature (Table 37-2). Congenital hernias, which make up the majority of pediatric hernias, can be considered an impedance of normal development, rather than an acquired weakness. During the normal course of development, the testes descend from the intra-abdominal space into the scrotum in the third trimester. Their descent is preceded by the gubernaculum and a diverticulum of peritoneum, which protrudes through the inguinal canal and ultimately becomes the processus vaginalis. Between 36 and 40 weeks, the processus vaginalis closes and eliminates the peritoneal opening at the internal inguinal ring.8 Failure of the peritoneum to close results in a patent processus vaginalis (PPV) and thus explains the high incidence of indirect inguinal hernias in preterm babies. It should be noted that the processus vaginalis continues to close as the child ages, with most closing within the first few months of life. Children with congenital indirect inguinal hernias will present with a PPV; however, its presence does not necessarily indicate an inguinal hernia (Fig. 37-1). In a study of nearly 600 adults undergoing laparoscopy for reasons not related to inguinal hernia repair, bilateral inspection of the internal inguinal rings revealed an incidence of 12% of PPV. None of these patients had clinically significant symptoms of a groin hernia.9 However, in a group of 300 patients undergoing unilateral laparoscopic inguinal hernia repair, 12% were found to have a contralateral PPV. Over the next 5 years, they developed inguinal hernias at a rate four times more than counterparts that had a closed ring.10


Table 37-2 Presumed Causes of Groin Herniation
Coughing
Chronic obstructive pulmonary disease
Obesity
Straining
  Constipation
  Prostatism
Pregnancy
Birthweight <1500 g
Family history of a hernia
Valsalva's maneuvers
Ascites
Upright position
Congenital connective tissue disorders
Defective collagen synthesis
Previous right lower quadrant incision
Arterial aneurysms
Cigarette smoking
Heavy lifting
Physical exertion (?)



The presence of a PPV likely predisposes the patient to the development of an inguinal hernia. This likelihood depends on the presence of other risk factors such as inherent tissue weakness, family history, and strenuous activity. Overall, there is limited data pertaining to the etiology of inguinal hernia development. Several studies have documented strenuous physical activity as a predisposing risk factor to acquiring an inguinal hernia.11,12 Repeated physical exertion may increase intra-abdominal pressure; however, whether this process occurs in combination with a PPV or through age-related weakness of abdominal wall musculature is unknown. A case-controlled study of over 1400 male patients with inguinal hernia revealed that a positive family history was eight times as likely to lead to development of a primary inguinal hernia. Chronic obstructive pulmonary disease significantly increased the risk of direct inguinal hernias.13 Interestingly, several studies have noted a protective effect of obesity. In a large, population-based prospective study of American individuals (First National Health and Nutrition Examination Survey), the risk of inguinal hernia development in obese men was only 50% that of normal weight males, while the risk in overweight males was 80% that of nonobese men. A possible explanation is the increased difficulty in detecting inguinal hernias in obese individuals.14

One of the most intriguing areas under study is the role of tissue biology in hernia formation. Epidemiologic studies have identified risk factors that may predispose to a hernia, but there are limited data specifically related to the molecular basis of these hernias. Early experiments involving iatrogenic laythirsm resulted in hernia formation. Furthermore, microscopic examination of skin of inguinal hernia patients demonstrated significantly decreased ratios of type I to type III collagen. Type III collagen does not contribute to wound tensile strength as significantly as type I collagen. Additional analyses of similar skin revealed disaggregated collagen tracts with decreased collagen fiber density.15 Collagen disorders such as Ehlers-Danlos syndrome also are associated with an increased incidence of hernia formation (Table 37-3). Tissue analysis has revealed that there is a relationship between the aneurysmal component and hernias, owing to a pathologic extracellular matrix metabolism.16 Although a significant amount of work remains to elicit the biologic nature of hernias, studies such as these provide compelling evidence for the presence of a genetic collagen defect.

Table 37-3 Connective Tissue Disorders Associated with Groin Herniation
Osteogenesis imperfecta
Cutis laxa (congenital elastolysis)
Ehlers-Danlos syndrome
Hurler-Hunter syndrome
Marfan syndrome
Congenital hip dislocation in children
Polycystic kidney disease
Alpha1-antitrypsin deficiency
Williams syndrome
Androgen insensitivity syndrome
Robinow's syndrome
Serpentine fibula syndrome
Alport's syndrome
Tel Hashomer camptodactyly syndrome
Leriche's syndrome
Testicular feminization syndrome
Rokitansky-Mayer-Küster syndrome
Goldenhar's syndrome
Morris syndrome
Gerhardt's syndrome
Menkes' syndrome
Kawasaki disease
Pfannenstiel syndrome
Beckwith-Wiedemann syndrome
Rubinstein-Taybi syndrome
Alopecia-photophobia syndrome

Anatomy

It cannot be overstated that proficient knowledge of inguinal anatomy is necessary to produce a lasting surgical cure of the inguinal hernia. The groin region is a complex network of muscles, ligaments, and fascia that are interwoven in a multiplanar fashion. To understand the anatomy of the groin, it is best to first consider its components and then conceptualize them according to operative approach. Because the vast majority of inguinal hernias occur in men, general descriptions of groin anatomy contained herein will pertain to males. The inguinal canal is approximately 4 to 6 cm long and is situated in the anteroinferior portion of the pelvic basin (Fig. 37-2). Shaped like a cone, its base is at the superolateral margin of the basin, with its apex pointed inferomedially toward the symphysis pubis. The canal begins intra-abdominally on the deep aspect of the abdominal wall, where the spermatic cord passes through a hiatus in the transversalis fascia (in females, this is the round ligament). This hiatus is termed the deep or internal inguinal ring. The canal then concludes on the superficial aspect of the abdominal wall musculature at the superficial or external inguinal ring, the point at which the spermatic cord crosses the medial defect of the external oblique aponeurosis. In the normal situation, parietal peritoneum covers the intra-abdominal portion of the spermatic cord, as well as the internal ring. Anteriorly, the boundary of the canal is comprised of the external oblique aponeurosis and internal oblique muscle laterally. Posteriorly, the floor of the inguinal canal is formed by the fusion of the transversalis fascia and transversus abdominus muscle, although up to one fourth of subjects are found to have only the transversalis fascia forming the posterior floor. The superior boundary is an arch formed by the fibers of the internal oblique muscle. Lastly, the inferior margin consists of the inguinal ligament. The spermatic cord consists of three arteries, three veins, and two nerves. As well, it contains the pampiniform venous plexus anteriorly and the vas deferens posteriorly, with connective tissue and remnant of the processus vaginalis between. The cord is then enveloped in layers of spermatic fascia.

Additional structures that are important to the conceptualization of the inguinal canal include the inguinal ligament, Cooper's ligament, iliopubic tract, lacunar ligament, and conjoined area (Fig. 37-3). The inguinal ligament is also known as Poupart's ligament and is comprised of the inferior fibers of the external oblique aponeurosis. The ligament stretches from the anterior superior iliac spine to the pubic tubercle. The ligament serves an important purpose as a readily identifiable boundary of the inguinal canal, as well as a sturdy structure used in various hernia repairs. Cooper's ligament is otherwise known as the pectineal ligament, although controversy exists as to whether it is, in fact, a ligament at all. Its anatomic site predisposes the structure to varied explanations of its nature and relationships to contiguous structures. For all intents and purposes, it can be considered as the lateral portion of the lacunar ligament that is fused to the periosteum of the pubic tubercle. It also may include fibers from the transversus abdominus, iliopubic tract, internal oblique, and rectus abdominus. The iliopubic tract is an aponeurotic band that begins at the anterior superior iliac spine and inserts into Cooper's ligament from above. It often is confused with the inguinal ligament secondary to common origin and insertion points. However, the iliopubic tract forms on the deep side of the inferior margin of the transversus abdominus and transversalis fascia. The inguinal ligament is on the superficial side of the musculoaponeurotic layer of these structures. The shelving edge of the inguinal ligament is a structure that more or less connects the iliopubic tract to the inguinal ligament. The iliopubic tract helps form the inferior margin of the internal inguinal ring as it courses medially, where it continues as the anterior and medial border of the femoral canal. The lacunar ligament, or ligament of Gimbernat, is the triangular fanning out of the inguinal ligament as it joins the pubic tubercle. Controversy exists as to whether the lateral edge of the lacunar ligament forms the medial border of the femoral canal. Controversy also exists as to the nature of the conjoined tendon. It is commonly described as the fusion of the inferior fibers of the internal oblique and transversus abdominus aponeurosis, at the point where they insert on the pubic tubercle. This exact anatomic entity is hard to describe consistently. More likely, the conjoined area is a combination of the transversus abdominus aponeurosis, transversalis fascia, lateral edge of the rectus sheath, and internal oblique muscle or its fibers.
Nerves of interest in the inguinal region are the ilioinguinal, iliohypogastric, genitofemoral, and lateral femoral cutaneous nerve (Figs. 37-4 and 37-5). The ilioinguinal and iliohypogastric nerve arise together from the first lumbar nerve (L1). The ilioinguinal nerve emerges from the lateral border of the psoas major and passes obliquely across the quadratus lumborum. At a point just medial to the anterior superior iliac spine, it crosses the internal oblique muscle to enter the inguinal canal between the internal and external oblique muscles and exits through the superficial inguinal ring. The nerve supplies the skin of the upper and medial thigh. In males, it also supplies the penis and upper scrotum, while supplying the mons pubis and labium majus in females. The iliohypogastric nerve arises from T12–L1 and follows the ilioinguinal nerve. After the iliohypogastric nerve pierces the deep abdominal wall in its downward course, it courses between the internal oblique and transversus abdominis, supplying both. It then branches into a lateral cutaneous branch and an anterior cutaneous branch, which pierces the internal oblique and then external oblique aponeurosis above the superficial inguinal ring. A common variant is for the iliohypogastric and ilioinguinal nerves to exit around the superficial inguinal ring as a single entity. The genitofemoral nerve arises from L1–L2, courses along the retroperitoneum, and emerges on the anterior aspect of the psoas. It then divides into the genital and femoral branches. The genital branch remains ventral to the iliac vessels and iliopubic tract as it enters the inguinal canal just lateral to the inferior epigastric vessels. In males, it travels through the superficial inguinal ring and supplies the scrotum and cremaster muscle. In females, it supplies the mons pubis and labia majora. The femoral branch courses along the femoral sheath, supplying the skin anterior to the upper part of the femoral triangle. The lateral femoral cutaneous nerve arises from L2–L3, but emerges from the lateral border of the psoas muscle at the level of L4. It crosses the iliacus muscle obliquely toward the anterior superior iliac spine. It then passes inferior to the inguinal ligament where it divides to supply the lateral aspect of the thigh (Fig. 37-6).
  

Anterior Perspective

The aforementioned borders of the inguinal canal can be readily appreciated when approaching an inguinal hernia in an open, anterior fashion. Once the subcutaneous tissue is passed, the oblique fibers of the external oblique aponeurosis are encountered. The external oblique muscle originates on the lower eight ribs (Fig. 37-7). The course of the fibers runs inferiorly from lateral to medial and is commonly referred to as hands in the pockets as they are parallel to one's fingers in this orientation. As the fibers approach the inguinal canal, they are no longer comprised of muscle, only tendinous aponeurosis. Once the aponeurosis is exposed, the superficial inguinal ring and inguinal ligament may be identified. The superficial ring consists of two crura. The medial crus is formed by the fibers of the external oblique aponeurosis and join with the lateral border of the rectus sheath. The inferior crus is formed by the inguinal ligament, which inserts into the pubic bone. The iliohypogastric nerve generally pierces the external oblique aponeurosis above the superficial inguinal ring. The spermatic cord, genitofemoral and ilioinguinal nerves are seen passing through the superficial inguinal ring. One layer deep to the external oblique aponeurosis, these same structures are visualized, as well as the deep inguinal ring. The inferior border of the internal inguinal ring is formed by the iliopubic tract, while the rest of the ring is formed by fibers of the transversalis fascia. Structures that are seen entering the internal inguinal ring include the spermatic cord and genital branch of the genitofemoral nerve.

The cord structures are enveloped by three fascial layers. The internal fascial layer is derived from the internal oblique muscle and contains the cremaster muscle. The external layer is adhered to the fascia of the external oblique muscle and must be dissected to mobilize the cord. The superficial fascia is also known as the fascia of Gallaudet or innominate fascia. Superior to the cord, the arch of the internal oblique muscle is seen fanning out to form the roof of the inguinal canal. The superior fibers are oriented perpendicular to the external oblique aponeurosis; however, the lower fibers run parallel with it, as they course toward the pubic bone (Fig. 37-8). 

Continuing posteriorly through the inguinal canal, the transversus abdominis muscle is encountered deep to the inguinal ring. It arises from the iliac crest, iliopsoas fascia, thoracolumbar fascia, and lower six costal cartilages. Regardless of site of origin, the fibers run in a lateral to medial fashion and it becomes less muscular and more aponeurotic medial, where it contributes to the rectus sheath and falx inguinalis. It is a commonly held belief that the integrity of the transversus abdominis muscle is the most important determinant to hernia formation. As its fibers contract, the arch of the transversus abdominis closes off the internal inguinal ring, thereby serving as a shutter mechanism. One layer deep to the transversus abdominis is the anterior and posterior lamina of transversalis fascia. Inferior to the arcuate line, the posterior covering of the anterior abdominal wall consists only of transversalis fascia, as the fascia of the external and internal oblique muscles fans out anteriorly to constitute the anterior layer of the rectus sheath. Deep to the transversalis fascia, the next layer encountered is the preperitoneal areolar tissue and fat. Dissection of this tissue and progression through the next layer, the peritoneum, allows one to enter into the peritoneal space. Therefore, the preperitoneal space is in actuality a potential space, bordered by the peritoneum on the deep aspect and transversalis fascia superficially.

The inferior epigastric vessels are best visualized from a posterior approach. The inferior epigastric artery is responsible for the blood supply to the rectus abdominis and connects the vasculature of the upper extremity to the lower extremity. The internal thoracic artery offshoots to form the superior epigastric artery, which anastomoses with the inferior epigastric artery, and is derived from the external iliac artery. The epigastric veins run with the arteries within the rectus sheath, posterior to the rectus muscles. Inspection of the internal inguinal ring will reveal the deep location of the inferior epigastric vessels. Inguinal hernias that protrude lateral to the inferior epigastric vessels, through the deep inguinal ring, are referred to as indirect inguinal hernias. Direct hernias, on the contrary, are protrusions medial to the inferior epigastric vessels, in Hesselbach's triangle. The borders of the triangle are as such: the inguinal ligament forms the inferior margin, the edge of rectus abdominis is the medial border, and the inferior epigastric vessels are the superior or lateral border.

From an anterior perspective, the femoral space can be visualized below the inguinal ligament. The iliopectineal arch is a fibrous band of fused iliac and psoas fascia that subdivides the space beneath the inguinal ligament into a lateral muscular space, housing the iliopsoas, femoral nerve, and lateral femoral cutaneous nerve, and a medial vascular space, containing the femoral vessels and femoral branch of the genitofemoral nerve. In addition to these components, the vascular space also houses a medial potential space known as the femoral canal and is the site of possible femoral hernia formation. The canal is shaped like a cone pointed inferiorly, extending to the fossa ovalis; the opening of the fascia latte for the great saphenous vein. The femoral ring is bordered by sturdy structures that lend to its inflexibility. The posterior boundary consists of the iliacus fascia and Cooper's ligament, and the anterior boundary is the iliopubic tract and inguinal ligament, internally and externally, respectively. Medially, the border is made up of the aponeurosis of transversus abdominis and the transversalis fascia and laterally, the canal is bordered by the femoral vein and its connective tissue. Normal contents of the femoral canal include areolar preperitoneal tissue and fat and lymph nodes, most notably the node of Cloquet at its upper end. The distal end of the canal is closed by fatty tissue called the septum femorale. Once the integrity of this septum is lost, femoral herniation occurs. Due to its small size and limited flexibility, the femoral ring is usually the site of incarceration. Reduction of incarcerated contents of a femoral hernia can thus be effected by splitting the inguinal ligament.

Posterior Perspective

Since laparoscopic procedures have been adapted as a treatment for inguinal hernias, surgeons have been required to reconceptualize the groin anatomy from the posterior perspective (Fig. 37-9). The large visual field and familiarity with intra-abdominal anatomy result in easier identification of the posterior groin region when inguinal hernias are approached intraperitoneally compared to the preperitoneal approach. Initial points of reference intraperitoneally are the five peritoneal folds, bladder, inferior epigastric vessels, and psoas muscle (Fig. 37-10). Beginning at the midline, the median umbilical fold can be easily identified in the lower midline. The fold represents the fibrous remnant of the fetal allantois, but may persist in the adult as a patent urachus. As one follows the median peritoneal fold from the umbilicus inferiorly, one encounters the pubic symphysis and bladder. Radiating down bilaterally, just lateral to this fold, is the medial umbilical fold, which represents the obliterated portion of the fetal umbilical artery. Less likely, a superior vesicular artery will persist within this fold, supplying the superior and lateral edge of the bladder, which is often found immediately medial to the medial umbilical fold, adjacent to the lateral edge of the bladder. Lateral to the medial umbilical ligament, the paired lateral umbilical fold contains the inferior epigastric vessels. The inferior epigastric artery is the lateral border of Hesselbach's triangle and thus provides a useful landmark to differentiate between direct and indirect hernias. A defect medial to the inferior epigastric vessels is considered direct, whereas a lateral defect is an indirect hernia. The type of hernia also can be elucidated by referring to the series of depressions that exist between the peritoneal folds. Progressing from midline laterally, one can identify the supravesical, medial, and lateral fossae. The supravesical fossa is found between the median and medial umbilical ligaments and leads to hernias of the same name. The medial fossa is located between the medial and lateral umbilical folds and is the site of direct hernias. The lateral fossa is found lateral to the lateral umbilical ligament and is the site of the internal inguinal ring and thus the location for indirect inguinal hernias. The superficial inguinal ring is not visualized from the peritoneal perspective. Most laterally, the psoas muscle is seen coursing inferiorly along the retroperitoneum. The anterior superior iliac spine is not readily apparent, but may be elucidated by palpating outside the abdomen. Identification of the internal inguinal ring then permits identification of the spermatic cord. Further inferior to the cord, the iliac vessels are identified deep to the peritoneum. Two potential spaces exist deep to the peritoneum, and these are encountered once the peritoneal flap is created. Between the peritoneum and the posterior lamina of the transversalis fascia is Bogros's space. This area contains preperitoneal fat and areolar tissue. A less prominent space exists between the posterior and anterior laminae of the transversalis fascia termed the vascular space, as this is the location of the inferior epigastric vessels.
Once the peritoneum is reflected to expose Bogros's space, the pertinent structures of preperitoneal inguinal anatomy can be identified. The most medial aspect of the preperitoneal space, that which lies superior to the bladder, is alternately known as the Retzius space. The pubic symphysis is identified by its midline location, white periosteum, and rigidness to palpation. The vasculature of the groin is much more apparent from the posterior perspective than from the anterior perspective. The inferior epigastric vessels are found in the same longitudinal plane as the iliac vessels. A common finding is the corona mortis, which is found overlying Cooper's ligament and represents a connection between the inferior epigastric and obturator vessels. The deep circumflex iliac vessels arise from the external iliac vessels and must be protected, as they may be intimately associated with the medial portion of the iliopubic tract. Exposure of the iliac vessels allows identification of the genital branch of the genitofemoral nerve as it courses with the external iliac artery. At the internal inguinal ring, the nerve joins the spermatic cord as it enters the inguinal canal.

The femoral branch of the genitofemoral nerve is found lateral to the genital branch and is seen leaving the retroperitoneum underneath the iliopubic tract. Also found laterally, and sometimes in association with the femoral branch of the genitofemoral nerve, is the lateral cutaneous nerve of the thigh. After emerging from the lateral edge of the psoas muscle, it, too, leaves the retroperitoneum inferior to the iliopubic tract to innervate the anterolateral skin of the thigh. The femoral nerve is not routinely seen during laparoscopic inguinal hernia repair but can be demonstrated lateral to the external iliac vessels between the iliacus and psoas muscles. The nerve courses beneath the iliopubic tract and inguinal ligament as it enters the thigh. The iliohypogastric and ilioinguinal nerves are more easily demonstrated via the anterior perspective because they do not cross into the operative space established by the preperitoneal approach.

The structures of the spermatic cord come together shortly before the cord enters through the internal inguinal ring. The vas deferens is of special note as it courses cephalad out from the pelvis and then crosses the inferior epigastric arteries to enter the spermatic cord inferomedially. Slightly inferior to the internal inguinal ring, the iliopubic tract is identified as it attaches to the iliac crest. On the medial side of the internal inguinal ring, Cooper's ligament can be demonstrated inserting inferolaterally into the pubic ramus. The pectineal ligament can also be identified on the medial aspect of the inferior epigastric vessels, along with the medial aspect of the femoral ring. The remainder of the boundaries of the femoral ring are also visualized. From the posterior perspective, this includes the iliopubic tract superiorly, Cooper's ligament inferiorly, and the femoral vein laterally.

The posterior perspective also allows excellent appreciation of the myopectineal orifice of Fruchaud (Fig. 37-11). The arch of the internal oblique muscle and transversus abdominis muscle constitute the superior margin, the iliopsoas muscle the lateral margin, the lateral edge of rectus abdominis medially, and the pubic pecten medially. The iliopubic tract divides the orifice into a superior portion housing the spermatic cord and an inferior portion containing the iliac vessels. The posterior perspective has also resulted in the characterization of important areas to avoid, known as the triangle of doom, triangle of pain, and the circle of death (Fig 37-12).17 The triangle of doom is bordered medially by the vas deferens and laterally by the vessels of the spermatic cord, thereby pointing its apex superiorly. The contents of the space include the external iliac vessels, deep circumflex iliac vein, femoral nerve, and genital branch of the genitofemoral nerve. The triangle of pain can be conceptualized as the space bordered by the iliopubic tract and gonadal vessels. The structures within this space include nerves such as the lateral femoral cutaneous, femoral branch of the genitofemoral, and femoral. The circle of death is a vascular continuation formed by the common iliac, internal iliac, obturator, aberrant obturator, inferior epigastric, and external iliac vessels. Basic knowledge of the boundaries of these triangles allows one to avert the dangers associated with injury to their contents.
Classification

A number of classification systems have been developed relating to inguinal hernias. The classification systems allow for standardization in comparing outcomes of various hernias, yet their clinical significance to date is limited. A common clinical classification system relates to location and subdivides hernias into indirect, direct, and femoral, although this system does not take into account the complexity of the hernia. Even this system has undergone considerable transformation with the concept of the myopectineal orifice of Fruchaud. Instead of examining the various locations of herniation independently, Fruchaud determined that a common site of weakness, the transversalis fascia, predisposes to all three hernias. With hernia treatment directed at restoring the integrity of this area, recurrences of all three hernias can be reduced. An ideal classification system would also be able to preoperatively stratify hernias and allow for the most appropriate approach to repair, rather than making management decisions based on intraoperative findings. However, preoperative classification relies heavily upon physical examination and the inherent subjectivity of it. Intraoperative classification is also complicated by the fact that certain components of an inguinal hernia cannot be assessed via the laparoscopic method.

A number of authors, including Rutkow, Robbins, Gilbert, Nyhus, and Schumpelick, have attempted to devise a standardized classification system. Gilbert's classification requires intraoperative assessment and divides hernias into five types, three indirect and two direct (Table 37-4). Type 1 hernias have a small internal ring, type 2 have a moderately dilated internal ring, and type 3 have a ring that is greater than two fingerbreadths. A type 4 direct hernia involved complete disruption of the inguinal floor, and type 5 represented direct hernias with a small diverticular opening of no more than one fingerbreadth.18 Rutkow and Robbins further expanded the Gilbert classification to include a type 6 pantaloon hernia, which is a combination of a direct and indirect hernia sac, and type 7 femoral hernia.19

Table 37-4 Gilbert Classification System
Type 1 Small, indirect
Type 2 Medium, indirect
Type 3 Large, indirect
Type 4 Entire floor, direct
Type 5 Diverticular, direct
Type 6 Combined (pantaloon)
Type 7 Femoral


The Nyhus classification is more detailed and assesses not only the location and size of the defect, but also the integrity of the inguinal ring and inguinal floor (Table 37-5). Consequently, this is one of the most widely used classifications. The system divides hernias into four types, with three subgroups for type III. A type I hernia has a normal size and configuration of the internal ring and occurs primarily as a congenital hernia. Type II hernias have a distorted and enlarged internal ring, without encroachment into the inguinal floor, and small hernia sac. Type IIIA hernias include small- to moderate-sized direct hernias without any sac component through the internal ring. Type IIIB hernias consist of large indirect hernias with defects that encroach on the inguinal canal floor, usually secondarily affecting the structure of the floor. Femoral hernias are classified as type IIIC, and recurrent inguinal hernias are type IV, with A representing direct, B indirect, C femoral, and D any combination of the previous three.20 Despite its general acceptance, the Nyhus classification scheme is limited by its subjectivity in assessment of distortion of the inguinal ring and posterior floor, especially laparoscopically.

Table 37-5 Nyhus Classification System
Type I Indirect hernia; internal abdominal ring normal; typically in infants, children, small adults
Type II Indirect hernia; internal ring enlarged without impingement on the floor of the inguinal canal; does not extend to the scrotum
Type IIIA Direct hernia; size is not taken into account
Type IIIB Indirect hernia that has enlarged enough to encroach upon the posterior inguinal wall; indirect sliding or scrotal hernias are usually placed in this category because they are commonly associated with extension to the direct space; also includes pantaloon hernias
Type IIIC Femoral hernia
Type IV Recurrent hernia; modifiers A–D are sometimes added, which correspond to indirect, direct, femoral, and mixed, respectively


A third major classification system was created by Schumpelick and enjoys greater application in Europe compared to North America. The major feature is the addition of orifice sizing to traditional systems. An L represents a lateral indirect site, M represents medial direct, and F for femoral. The defects are then graded according to size with type I being <1.5 cm in diameter, type II being 1.5 to 3 cm, and type III being >3 cm.21 Although the system purports to be more objective, differences in the extent of abdominal distention during pneumoperitoneum may affect measurements. A significant amount of other classification systems exist, although no single system has been widely embraced by all surgeons. Future systems will have to take into account ease of use, objectivity, and account for varying anatomic perspectives between open and laparoscopic surgery.

Diagnosis

History

Inguinal hernias present along a spectrum of scenarios. These range from incidental findings to symptomatic hernias to surgical emergencies such as incarceration and strangulation of hernia sac contents. Asymptomatic inguinal hernias are frequently diagnosed incidentally on physical examination or may be brought to the patient's attention as an abnormal bulge. In addition, these hernias can be identified intra-abdominally during laparoscopy. Inspection of the pelvis following mobilization of intestinal contents into the upper abdomen will reveal the myopectineal orifice and allow facile identification of the peritoneum herniating through the direct, indirect, or femoral space.

Patients who present with a symptomatic groin hernia will frequently present with groin pain. Less commonly, patients will present with extrainguinal symptoms such as change in bowel habits or urinary symptoms. Regardless of size, an inguinal hernia may impart pressure onto nerves in the proximity, leading to a range of symptoms. These include generalized pressure, local sharp pains, and referred pain. Pressure or heaviness in the groin is a common complaint, especially at the conclusion of the day, following prolonged activity. Sharp pains tend to indicate an impinged nerve and may not be related to the extent of physical activity performed by the patient. Lastly, neurogenic pains may be referred to the scrotum, testicle, or inner thigh. Questions also should be directed to elucidating the extrainguinal symptoms. A change in bowel habits or urinary symptoms may indicate a sliding hernia consisting of intestinal contents or involvement of the bladder within the hernia sac.

Important considerations of the patient's history include duration and progressiveness of the symptoms. Hernias will often increase in size and content over a protracted time. Much less commonly, a patient will present with a history of acute inguinal herniation following a strenuous activity. However, it is more likely that an asymptomatic, previously unknown, inguinal hernia became evident once the patient experienced symptoms associated with the circumstances of the acute event. Notwithstanding the type of presentation, specific questions should be focused as to whether the hernia is reducible. Oftentimes, patients will reduce the hernia by pushing the contents of the bulge back into the abdomen, thereby providing temporary relief. As the size of a hernia increases and a larger amount of intra-abdominal contents fill the hernia sac, the bulge may become harder to reduce.

Physical

Although the history may be tremendously indicative of an inguinal hernia, the physical examination is essential to forming the diagnosis. A significant drawback exists in morbidly obese patients, where delineation of external groin anatomy is difficult and may obscure the findings of a groin hernia. Ideally, the patient should be examined in a standing position, with the groin and scrotum fully exposed. The standing position has the advantage over the supine position in that intra-abdominal pressure is increased, and thereby, the hernia can be more easily elicited. Inspection is performed first, with the goal of identifying an abnormal bulge along the groin or within the scrotum. If an obvious bulge is not detected, physical examination is performed to confirm the presence of the hernia.

Palpation is performed by placing the index finger into the scrotum, aiming it toward the external inguinal ring (Fig. 37-13). This allows the inguinal canal to be inspected. The patient is then asked to cough or bear down (i.e., Valsalva's maneuver) to protrude the hernia contents. Reproduction of patient symptoms, namely vague, generalized pressure sensations, will not usually be reproduced by these maneuvers, as they are a product of prolonged pressure on the cord contents. However, a Valsalva's maneuver will reveal an abnormal bulge and allow the clinician to determine whether the bulge is reducible or not. Examination of the contralateral side affords the clinician the opportunity to compare the extent of herniation between sides. This is especially useful in the case of a small hernia. The magnitude of the bulge on the affected side can be compared to the normal bulging of muscle on the nonaffected side, when the abdomen is placed under strain. However, the results may be misleading if there is a latent contralateral hernia that is discovered during this examination.

Certain techniques of the physical examination have classically been used to differentiate between direct and indirect hernias. The inguinal occlusion test involves placement of a finger over the internal inguinal ring and the patient is instructed to cough. If the cough impulse is controlled, then the hernia is indirect. If the cough impulse is still manifest, the hernia is direct. As well, with a finger in the inguinal canal, the cough impulse can be used to determine the type of hernia. If the cough impulse is felt on the fingertip, the hernia is indirect; if felt on the dorsum of the finger, it is deemed direct. However, when results of clinical examination are compared against operative findings, there is a probability somewhat higher than chance (i.e., 50%) of correctly diagnosing the type of hernia.22,23 Therefore, the utility of these tests should not be used to diagnose the type of inguinal hernia insomuch as they should be used to determine the presence or absence of one.

A further challenge to the physical examination is the identification of a femoral hernia. The anatomic position of a femoral hernia dictates that it should be palpable below the inguinal ligament, lateral to the pubic tubercle. As a consequence of increased subcutaneous tissue, a femoral hernia may be missed or misdiagnosed as a hernia of the inguinal canal. In contrast, a prominent fat pad in a thin patient may prompt an erroneous diagnosis of femoral hernia, otherwise known as a femoral pseudohernia.

In addition to inguinal hernia, a number of other diagnoses may be considered in the differential of a groin bulge (Table 37-6). The diagnosis is ambiguous; radiologic investigation may provide the answer.

Table 37-6 Differential Diagnosis of Groin Hernia
Malignancy
  Lymphoma
  Retroperitoneal sarcoma
  Metastasis
  Testicular tumor
Primary testicular
  Varicocele
  Epididymitis
  Testicular torsion
  Hydrocele
  Ectopic testicle
  Undescended testicle
Femoral artery aneurysm or pseudoaneurysm
Lymph node
Sebaceous cyst
Hidradenitis
Cyst of the canal of Nuck (female)
Saphenous varix
Psoas abscess
Hematoma
Ascites


Imaging

A number of situations can make the usually straightforward diagnosis of inguinal hernia ambiguous. These scenarios include obese patients, hernias that cannot be elicited on physical examination, and recurrent inguinal hernias. In these situations, radiologic investigations may be used as an adjunct to history and physical examination. The most common radiologic modalities include ultrasonography (US), computed tomography (CT), and magnetic resonance imaging (MRI). Each technique has certain advantages over physical examination alone; however, each also is associated with potential pitfalls.

Ultrasound is the least invasive technique and does not impart any radiation to the patient. Anatomic structures can be more easily identified by the presence of bony landmarks; however, because there are few in the inguinal canal, other structures such as the inferior epigastric vessels are used to define groin anatomy. Positive intra-abdominal pressure is used to elicit the herniation of abdominal contents. Movement of these contents is essential to making the diagnosis with US, and lack of this movement may lead to a false negative. In thin patients, normal movement of the spermatic cord and posterior abdominal wall against the anterior abdominal wall may lead to false-positive diagnoses of hernia.24

CT and MRI provide static images that are able to delineate the groin anatomy and demonstrate not only the presence of groin hernias, but also rule out differential diagnoses that may cloud the clinical picture (Fig. 37-14). Although CT scan is useful in ambiguous clinical presentations, little data exist to support its routine use in diagnosis. The use of MRI in assessing groin hernias was examined in a group of 41 patients scheduled to undergo laparoscopic inguinal hernia repair. Preoperatively, all patients underwent US and MRI. Laparoscopic confirmation of the presence of inguinal hernia was deemed the gold standard. Physical examination was found to be the least sensitive, whereas MRI was found to be the most sensitive. False positives were low on physical examination and MRI (one finding), but higher with US (four findings). With further refinement of technology, radiologic techniques will continue to improve the sensitivity and specificity rates of diagnosis, thereby serving a supplementary role in cases of uncertain diagnosis.

Anesthesia

Local, regional, and general anesthesia are all viable options for open anterior hernia repairs. Laparoscopic repairs, on the other hand, usually are performed using general anesthesia for optimal abdominal expansion and patient comfort. This limitation of laparoscopic surgery becomes a consideration in high-risk patients that cannot tolerate general anesthesia and the effects of pneumoperitoneum. In contrast, there are relatively few side effects of local anesthesia, which can facilitate operative tolerance by the patient, especially when combined with an IV sedative or anxiolytic agent.

Local anesthesia is applied by the surgeon before the initial groin incision. Common anesthetic agents include lidocaine and the longer-acting bupivacaine, both with optional epinephrine. Patients with a history of coronary artery disease have a relative contraindication to epinephrine use. The maximum dose should be calculated according to the patient's weight during preparation of the injection. In advance of the initial incision, usually before the prep and drape, a variable amount of anesthetic is injected one fingerbreadth medial and inferior to the anterior superior iliac spine to block the ilioinguinal nerve. In addition, anesthetic is injected along the cutaneous course of the skin incision and underlying subcutaneous tissue. The remaining amount is reserved for repeated applications to affected areas during the course of the operation. A combination of the two agents provides for a quick onset and prolonged control of pain, in the range of 18 hours.

Regional anesthesia, such as epidural, is another option reserved for patients that cannot tolerate general anesthesia. It also has a greater margin of patient comfort. Additional advantages of local and regional anesthesia include the ability of the patient to cough or Valsalva to test the repair. The versatility of anesthesia choices is a common argument for proponents of open inguinal hernia repairs. Nonetheless, the majority of procedures are performed using general anesthesia, which provides the greatest margin of patient comfort of all three choices. Advances in perioperative care have allowed for extensive general anesthesia use in an ambulatory surgery setting. Long- or short-acting local anesthetics can be applied to the incisions at the end of the procedure to prolong pain control. Common cardiorespiratory complications of anesthesia include myocardial depression, infarct, and aspiration pneumonia. The risk of these complications is reduced by using local anesthesia; however, anesthesiologists may prefer to completely sedate the patient and thereby control the airway. It should be noted that most procedures using only local anesthesia are performed at specialty hernia centers.

Treatment

The treatment of inguinal hernias can be subdivided according to approach (i.e., open vs. laparoscopic). Open inguinal hernias can be further subdivided according to whether the repair is performed anterior or posterior to the inguinal floor. A large number of open inguinal hernia repairs have been described over time; however, the most commonly performed and clinically pertinent procedures will be described herein.

Open Approach

Before the widespread use of prosthetic material, inguinal hernia repairs were based on restoring tissue strength through the use of sutures. Upon the introduction of prosthetics in the tension-free repair, these procedures came to be known as tension repairs; however, this would imply that these procedures do not adhere to basic surgical principles of avoiding tension between tissues. Therefore, these will be referred to as tissue repairs. Despite the advantages of the tension-free prosthetic repair, tissue repairs occupy an important place in the choice of inguinal hernia repair, especially in situations where prosthetic material is contraindicated. This includes a contaminated operative field or concern regarding possible azoospermia secondary to long-term effects of mesh on the vas deferens.25

Exposure of the inguinal region is common to open approaches to inguinal hernia repair. An oblique or horizontal incision is performed over the groin (Fig. 37-15). A point two fingerbreadths inferior and medial to the anterior superior iliac spine is chosen as the most lateral point of the incision. It is then progressed medially for approximately 6 to 8 cm. Electrocautery is then used to divide the subcutaneous tissue. Fascia of Camper is not routinely encountered; however, Scarpa's fascia generally is identified and then divided, thereby exposing the aponeurosis of the external oblique muscle. A vein coursing in a vertical fashion through the subcutaneous tissue frequently is encountered and is ligated and divided between hemostat clamps. The fibers of the external oblique muscle are then sharply divided parallel to the direction of fibers. Metzenbaum scissors are then advanced immediately beneath the fibers, laterally and then medially toward the external inguinal ring, and spread as they are retracted to create a space and avoid inadvertent dissection of the ilioinguinal nerve. The scissors are then used to incise the aponeurosis, splitting the external inguinal ring, exposing the inguinal canal and its contents. The aponeurosis is divided superior to the inguinal ligament as consideration should be made for its reapproximation once the repair is complete.
Mobilization of the Cord Structures

Hemostat clamps are then applied to the superior and inferior edges of the aponeurosis and elevated from the inguinal canal. Blunt dissection is then performed to separate the superior flap of the external oblique aponeurosis from the internal oblique muscle. Likewise, the inferior flap of the external oblique aponeurosis is bluntly dissected to reveal the shelving edge of the inguinal ligament. The iliohypogastric and ilioinguinal nerves are identified and may be retracted from the operative field by placing a hemostat beneath their course and then grasping one of the edges of the aponeurosis. Some surgeons routinely divide these nerves to avoid possible entrapment; however, the sequelae involve permanent paresthesia to sites of their cutaneous distribution. The pubic tubercle is then identified and the surgeon's index finger and thumb are placed around the cord as it passes the tubercle. A Penrose drain or metal cord ring may then be placed around the cord and its contents to permit its elevation from the floor of the inguinal canal. With the cord elevated at the external inguinal ring, cremasteric fibers are visualized connecting the floor of the inguinal canal to the posterior aspect of the cord. The cremasteric fibers can then be divided bluntly or through the use of electrocautery to initiate skeletonization of the cord. Once the cremasteric fibers are completely divided between the external and internal inguinal rings, the floor of the inguinal canal can be fully assessed for direct hernias. Care must be taken to avoid injury to cord structures during the division of the cremasteric muscle.

Identification and Reduction of the Sac

With the contents of the inguinal canal completely encircled, identification of cord contents and the hernia sac can be effected. Direct hernias will become evident as the floor of the inguinal canal is dissected. Even in tension-free repairs, the floor of the inguinal canal may be imbricated with stitches to reduce the direct hernia sac. An indirect hernia sac will generally be found on the anterolateral surface of the spermatic cord. In addition to sac identification, the vas deferens and vessels of the spermatic cord must be identified to allow dissection of the sac from the cord. At the leading edge of the sac, the two layers of peritoneum will fold upon themselves and reveal a white edge, which may help in the identification of the sac. This peritoneum can then be grasped with a tissue forceps and bluntly dissected from the cord. The dissection is carried proximally toward the deep inguinal ring.

The reduction of the hernia sac into the preperitoneal space is commonly known as high ligation of the sac. Some surgeons will routinely open the sac and inspect it to ensure there is no incarceration of intra-abdominal contents. As well, the decision must be made whether to excise the sac at the internal inguinal ring or simply invert it into the preperitoneum. Both methods are effective in reducing the sac; however, in a large prospective randomized study, patients undergoing high ligation and excision of the sac had significantly increased postoperative pain in the first week.26 A densely adherent sac, which may result in injury to cord structures, does not necessarily deserve dissection; however, division at the internal inguinal ring is necessary. Likewise, an inguinal hernia sac that extends into the scrotum may require division within the inguinal canal. Attempts to reduce such sacs may be met with postoperative complications related to injury of the pampiniform plexus, including testicular atrophy and orchitis.

Wound Closure

Once the reconstruction of the inguinal canal is complete, the cord contents are returned to their anatomic position. The external oblique aponeurosis is then reapproximated. A useful starting position is at the external inguinal ring. Using an absorbable suture, the external inguinal ring is reconstructed and the external oblique fascia is then closed using a running stitch that progresses laterally. Avoidance of an overly constricting external ring will prevent compression of cord structures at that point. However, it should be small enough to contain the contents of the inguinal canal and prevent a future false-positive diagnosis of recurrent hernia. Scarpa's fascia may then be closed with a series of interrupted absorbable sutures. Lastly, skin is closed with a subcuticular stitch to preserve cosmesis of the incision.

Anterior Repairs, Nonprosthetic

Before the introduction of mesh prostheses, open anterior inguinal hernia repairs were performed by reapproximating tissue using only sutures. Despite their shortcomings, specific procedures such as the Bassini, Shouldice, and McVay repair continue to occupy a minor, yet important role in the overall treatment of inguinal hernias. The introduction of the Bassini repair was superior to previously performed procedures in that, not only was the hernia reduced and the defect oversewn, but now an attempt was made to reconstruct the site of weakness, although these tissue-based repairs tend to place tension on the reconstructed tissue. The Shouldice repair is an exception because the multilayer reconstruction distributes the tension, effectively resulting in a tension-free repair. Hernia exposure and reduction are common to all open anterior repairs; however, the mode of restoration of inguinal canal integrity differs according to procedure.

Bassini Repair

The Bassini repair was a major advancement in the treatment of inguinal hernias owing to significantly reduced recurrence rates as compared to other operations of the day. Current use of the Bassini repair is limited because other tissue-based operations such as the Shouldice repair have demonstrated lower recurrence rates. The importance of the Bassini repair lies in the paradigm shift it promoted, which included dissection of the spermatic cord, dissection of the hernia sac with high ligation, and extensive reconstruction of the floor of the inguinal canal (Fig. 37-16). Following division of the cremasteric muscle and ligation of the hernia sac deep to the internal inguinal ring, the transversalis fascia is incised from the pubic tubercle to the internal inguinal ring, thereby entering the preperitoneal space. Preperitoneal fat is bluntly dissected from the upper margin of the posterior side of the transversalis fascia to permit adequate tissue mobilization. A triple-layer repair is then performed to restore integrity to the floor. The medial tissues, including the internal oblique muscle, transversus abdominis muscle, and transversalis fascia, are fixed to the shelving edge of the inguinal ligament and pubic periosteum with interrupted sutures. The lateral border of the repair is the medial border of the internal inguinal ring, which subsequently is reinforced by the repair. Adoption of the Bassini technique in North America resulted in injury to neurovascular structures and high recurrence rates because the posterior floor was not routinely opened. Nevertheless, the significant advances promulgated by Bassini still resulted in a recurrence rate that could be further improved. Numerous modifications of the technique by successive surgeons accomplished a lower recurrence rate, namely with the addition of the relaxing incision and the Shouldice technique. Current use of the Bassini technique is limited, although a modification may be useful in large direct hernias approached via an open approach. In these cases, imbrication of the posterior floor may be added to a tension-free repair with mesh
Shouldice Repair

The principles of the Bassini repair were revitalized within the Shouldice repair, resulting in superior recurrence rates. Although the Shouldice repair is generally grouped with open tissue-based repairs, its success rates are equivalent to that of tension-free repairs in many studies comparing the two approaches. As with the Bassini repair, the primary tenets of the procedure involve extensive dissection and reconstruction of inguinal canal anatomy. The use of a continuous suture in multiple layers resulted in the dual advantage of distributing tension over several layers and preventing subsequent herniation between interrupted sutures (Fig. 37-17). Original descriptions of the Shouldice technique involved the use of a stainless steel wire; however, modern modifications have resulted in the use of a synthetic nonabsorbable suture. With the posterior inguinal floor exposed, an incision in the transversalis fascia is performed between the pubic tubercle and internal ring. Care is taken to avoid injury to any preperitoneal structures, and these are bluntly dissected to mobilize the upper and lower fascial flaps. The first layer of repair begins at the pubic tubercle where the iliopubic tract is sutured to the lateral edge of the rectus sheath, then progressing laterally. The inferior flap of the transversalis fascia, which includes the iliopubic tract, is sutured continuously to the posterior aspect of the superior flap of the transversalis fascia until the internal ring is encountered. At this point, the internal ring has been reconstituted. The suture is not tied here, but rather is continued back upon itself in the medial direction. At the internal ring, the second layer is the reapproximation of the superior edge of the transversalis fascia to the inferior fascial margin and the shelving edge of the inguinal ligament. The suture is then tied to the tail of the original stitch. A third suture is started at the tightened inguinal ring, joining the internal oblique and transversus abdominis aponeuroses to external oblique aponeurotic fibers just superficial to the inguinal ligament. This layer is continued to the pubic tubercle where it reverses upon itself to create a fourth suture line, which is similar and superficial to the third layer. Unique to this operation is the routine division of the genital branch of the genitofemoral nerve. The consequence of loss of skin sensation is countered by the observed decrease in recurrence rate at the pubic tubercle. The Shouldice technique is readily apparent in common practice, especially in specialized hospitals treating inguinal hernias. 

McVay Repair

The advantage of the McVay (Cooper's ligament) repair is the ability to address both inguinal and femoral canal defects. Femoral hernias that are approached via a suprainguinal ligament approach, or situations where the use of prosthetic material is contraindicated, are amenable to this type of repair. The operation was popularized by McVay, who also added the concept of the relaxing incision as a tension reducing maneuver (Fig. 37-18). Once the cord has been isolated, a transverse incision is performed through the transversalis fascia, thereby entering the preperitoneal space. A small amount of dissection of the posterior aspect of the fascia is performed to allow mobilization of the upper margin of the transversalis fascia. The floor of the inguinal canal is then reconstructed to restore its strength. Cooper's ligament is identified medially, and it is bluntly dissected to expose its surface. The upper margin of the transversalis fascia is then sutured to Cooper's ligament. The repair is continued laterally along Cooper's ligament, occluding the femoral canal.
Once the femoral canal has been passed, a transition stitch is performed by now suturing the transversalis fascia to the inguinal ligament. The transition stitch helps obliterate the femoral canal, but more importantly, avoids injury to the femoral vessels. The transversalis fascia is subsequently sutured to the inguinal ligament, the lateral margin being the internal inguinal ring, which consequently undergoes transformation to a smaller, tighter ring. The repair can be performed using either interrupted sutures or a continuous stitch. An essential component of the procedure is the relaxing incision, which helps reduce the considerable amount of tension that normally results. Before suturing the transversalis fascia to Cooper's and the inguinal ligament, an incision in the anterior rectus sheath is made. The incision begins at the pubic tubercle and is extended superiorly for approximately 2 to 4 cm.

Potential consequences of the relaxing incision include increased postoperative pain and less likely herniation at the anterior abdominal wall. Disadvantages of routinely performing the McVay Cooper's ligament repair include elevated recurrence rates due to the tissue-based nature of the operation. Furthermore, the procedure requires extensive dissection and may result in injury to the underlying femoral vessels.

Anterior Repairs, Prosthetic

Outside of specialized centers dealing with inguinal hernias, recurrence rates of tissue-based repairs continued to be high, owing to the tension placed on reconstructed tissues. To circumvent this problem and adhere to no-tension principles of effective surgical repair, mesh herniorrhaphies were developed. The addition of a mesh prosthesis effected a reconstruction of the posterior inguinal canal, without placing tension on the floor itself, hence a tension-free repair, as championed by Lichtenstein. Further refinements have included the addition of a plug through the internal ring, resulting in the plug and patch repair. The consistently superior recurrence rates over the long-term, along with the ease of reproducibility of these techniques, resulted in the wide acceptance of tension-free repairs for inguinal hernias.

Lichtenstein Tension-Free Repair

Initial exposure and mobilization of cord structures is identical to other open approaches. Particular attention must be paid to blunt dissection of the inguinal canal to expose the shelving edge of the inguinal ligament and pubic tubercle, as well as provide a large area for mesh placement. Unlike the tissue-based repairs, the Lichtenstein repair does not include routine division of the transversalis fascia, thereby preventing the identification of a latent femoral hernia. However, in the case where a clinically significant hernia is not visualized upon entrance into the inguinal canal, an argument can be made to enter the preperitoneal space and evaluate the femoral canal. The lack of inguinal floor division also indicates that the internal inguinal ring is not reconstructed using canal structures (Fig. 37-19). Instead, the floor and internal ring are reinforced through the application of the mesh.

The mesh is rectangular in shape, with a rounded edge at its apex, corresponding to the medial edge. At the other end, the mesh will be split to accommodate the spermatic cord. The mesh prosthesis must be large enough to adequately cover the posterior wall of the inguinal canal and can be sized accordingly when placed into the field. The rounded edge is attached to the anterior rectus sheath just medial to the pubic tubercle, ensuring that there is an adequate overlap medially to prevent recurrence. The suture is then continued in a running fashion to secure the mesh around the pubic tubercle. Care must be taken to avoid placing sutures directly into the periosteum of the pubic tubercle, which may result in persistent postoperative pain. The inferior margin of the mesh is then sutured to the shelving edge of the inguinal ligament, as the repair is continued laterally. The stitch is then tied at the internal ring. The mesh is then tailored to fit around the cord at the internal ring. The slit in the lateral end of the mesh may require expansion to accommodate the cord and prevent strangulation of cord contents. The superior and inferior flaps of the prosthesis are then placed around the base of the cord, lateral to the internal ring and near the anterior superior iliac spine, and sutured together with a single interrupted stitch. This allows the internal ring to be reinforced by a synthetic valve, helping to prevent recurrences of indirect inguinal hernias.

A flap closure that is too lose may lead to higher indirect hernia recurrences; however, one that is too tight may impart significant pressure on the spermatic cord, leading to the injury of its contents. The superior edge of the mesh is then fixed to the posterior aspect of the internal oblique aponeurosis and rectus sheath, using either interrupted or continuous sutures. Fixation of the upper and lower margin of the mesh too superficially to the internal and external oblique aponeuroses may shorten the superior and inferior flaps of the external oblique aponeurosis, making closure of the inguinal canal difficult. In the case of a femoral hernia, the inferior margin of the mesh is sutured to Cooper's ligament medially and inguinal ligament laterally, similar to McVay's repair. Nonabsorbable or long-term absorbable sutures generally are used with mesh repairs.

Plug and Patch Technique

A modification of the Lichtenstein repair, known as the plug and patch technique, was developed by Gilbert and later popularized by Rutkow and Robbins.27 In addition to placement of the prosthesis in a similar fashion to the Lichtenstein repair (i.e., the patch), the technique includes placement of a prosthesis (i.e., the plug) through the internal ring (Fig. 37-20). The internal ring is therefore reinforced by the leaflets of the patch as well as the plug. Initial technique described rolling a flat piece of polypropylene into a tight cylinder and placing it alongside the spermatic cord as it passes through the internal ring. Further modifications have involved shaping the plug into a flower or umbrella configuration, with the apex pointed intra-abdominally, in effect serving as a preperitoneal prosthesis. Increased abdominal pressure acts on the plug, opening its leaflets and creating a protective valve. Original descriptions of the plug and patch procedure emphasized a pure tension-free approach in that the plug and patch could be placed in their anatomic positions without sutures. Normal scarring would then fix the prostheses in place and provide reconstituted strength to the inguinal canal. Currently, preformed plugs in various sizes are available and are usually fixed to the margins of the internal ring with one or several interrupted sutures.28 Direct defects may also be plugged; however, in the absence of inguinal floor division and dissection, suture fixation of the plug to the margins of the defect is necessary. In this case, the plug is fixed to Cooper's and the inguinal ligament inferiorly and the internal oblique aponeurosis superiorly. Numerous modifications of the plug and patch technique have occurred with various extents of prosthesis fixation. Considerations unique to the plug include intra-abdominal migration and erosion into contiguous structures.
Preperitoneal Repairs

As previously noted in the Bassini Repair section, the preperitoneal space can be entered using the anterior approach by dividing the transversalis fascia; however, wide exposure of the preperitoneal space is limited. Therefore, a number of surgeons have approached the preperitoneal space posterior to the transversalis fascia. Cheatle was the first to perform posterior preperitoneal repair of a groin hernias, usually through a lower midline and later using a Pfannenstiel incision. Nonprosthetic preperitoneal repairs were also described by Nyhus; however, the superior results achieved by mesh use lend them to historical significance only. The placement of a widely overlapping prosthesis in the preperitoneal space using the open approach eventually became the basis of laparoscopic surgery. The strength of the transversalis fascia is reinforced by the addition of the prosthesis deep to it. The perceived advantage of the preperitoneal approach is that the prosthesis can be placed between hernia contents and the hernia defect. Furthermore, increases in intra-abdominal pressure serve to push the mesh against the floor of the inguinal canal, unlike in anterior mesh placement where the mesh is pushed away. The posterior approach to preperitoneal repairs avoids entry into the inguinal canal and permits optional closure of the hernia defect. Therefore, nerves that course through the inguinal canal are avoided, and there is minimal manipulation of the spermatic cord. A Pfannenstiel or lower midline incision is generally used to gain access to the preperitoneal space, taking care not to disturb the peritoneum. The preperitoneal space can also be accessed intra-abdominally; however, this approach is optimal if a laparotomy is being performed for other purposes. A notable example is a laparotomy performed for bowel obstruction that results in the identification of an inguinal hernia as the cause of obstruction.

Read-Rives Repair

The anterior approach to preperitoneal repairs, as described by Read and Rives, accesses the groin using a standard groin incision (Fig. 37-21). The transversalis fascia is incised and a wide blunt dissection of the preperitoneal space is performed to accommodate a large prosthesis. The spermatic cord is identified at the internal ring and dissected from the peritoneum proximally to the pelvic portion of the vas deferens. The vas deferens is separated from the spermatic vessels during the course of cord parietalization. Cooper's ligament must also be identified medially and dissected free to expose its surface. Dissection to this extent frees the peritoneum from the iliac fossa and provides an adequate space for placement of a large prosthesis. An unsplit piece of mesh, approximately 16 x 12 cm is then placed in the preperitoneal space over the spermatic cord, ensuring overlap medial to Cooper's ligament, laterally to the anterior superior iliac spine and inferiorly to the margin of the preperitoneal dissection. The mesh is secured using three sutures, to Cooper's ligament, the pubic tubercle, and the psoas muscle. The transversalis fascia is then reclosed, and the inguinal canal is closed routinely as per the open approach.
Giant Prosthetic Reinforcement of the Visceral Sac

The giant prosthetic reinforcement of the visceral sac is also known as the Rives, Stoppa, or Wantz repair, although minor modifications exist between them. Ideal access is provided by a Pfannenstiel or lower transverse incision, which is more medial than a standard groin incision in anterior open approaches. The incision ranges 8 to 10 cm from the midline laterally, above the level of the internal ring. The intent is to expose the lateral aspect of the rectus sheath and divide it and the oblique muscles for a distance of 10 cm. Abdominal wall muscles are then retracted to expose the transversalis fascia, allowing it to be incised. The peritoneum is left intact to maintain the procedure within the preperitoneal space. Wide dissection is then performed posterior to the rectus sheath and inferior epigastric vessels (Fig. 37-22). The dissection begins on the contralateral side of the midline and continues laterally to beyond the anterior superior iliac spine. Inferiorly, the peritoneum is dissected to the division of the spermatic vessels and vas deferens. The posterior approach requires identification of Cooper's ligament medially and the iliopubic tract running laterally. A direct hernia will be identified and reduced during the course of initial dissection. Care must be taken to separate the hernia sac from the overlying transversalis fascia because an incorrect plane of dissection may be entered, resulting in dissection of the anterior abdominal wall. Direct defects can be ignored, or conversely, the defect can be imbricated or obliterated by suturing the transversalis fascia to Cooper's ligament. An indirect hernia will be identified at the internal ring and usually will require additional directed dissection. The advantage to the preperitoneal approach is minimal interaction with the spermatic cord. Therefore, in the case of large or densely adherent indirect hernia sacs that pose a problem during cord parietalization, ligation of the sac may be undertaken. The distal sac is left untouched, and the sac, at its insertion at the internal ring, is dissected from the spermatic cord. The resulting defect in the peritoneum is then closed to restore the peritoneal lining. Because the sac is bilayered, it can be opened on the side not adherent to the cord and dissected away until it can be circumferentially freed and divided.
A large mesh is then aseptically prepared for placement into the dissected space. The width of the mesh should span a distance between the umbilicus and anterior superior iliac spine, minus 1 cm, and the height should be approximately 14 cm. Variations of mesh preparation include an intact mesh vs. a slit mesh. A slit in the lateral aspect accommodates the spermatic cord, similar to mesh placement in the Lichtenstein tension-free repair. Splitting of the mesh creates a small defect in its integrity, which may predispose it to a hernia recurrence. Proponents for a slit or keyhole argue that mesh positioning is optimal and obviates the need for fixation sutures. Fixation is an important consideration when avoiding preperitoneal structures such as the lateral femoral cutaneous nerve and inferior epigastric vessels. Wantz's technique advocates the placement of three absorbable sutures that attach the superior border of the mesh to the anterior abdominal wall above the level of the indirect or direct defect. The location of fixation sutures includes the linea alba, linea semilunaris, and anterior superior iliac spine. Long clamps placed along the inferior border of the prosthesis facilitate flat placement along the inferior margin of the preperitoneal space (Fig. 37-23). The clamps are placed along the lower corners of the mesh and one in between. The mesh should be placed in a flat, taut position, avoiding any scrolling of the inferior border. The medial clamp is directed into the space of Retzius, the middle clamp over the pubic ramus and iliac vessels, and the lateral clamp is placed into the iliac fossa to provide coverage of the spermatic cord. The clamps are removed as the peritoneal is brought into apposition with the prosthesis. In the case of bilateral hernias, Stoppa advocates the use of a single large mesh spanning the area between the two anterior superior iliac spines minus 2 cm. The height is the distance between the umbilicus and the pubis. The large mesh requires the application of eight clamps to the lower border to facilitate proper placement. Although the approach provides excellent coverage and reinforcement of the preperitoneal space, postoperative pain and recovery is a significant consideration (Fig. 37-24).
Iliopubic Tract Repair

The iliopubic tract repair was popularized by Nyhus and Condon following extensive anatomic study detailing the importance of the iliopubic tract. The preperitoneal approach does not allow for visualization of the inguinal ligament; however, the iliopubic tract serves an analogous function in the preperitoneal space by providing a strong point of fixation. The repair combines a preperitoneal tissue-based repair with the implantation of mesh. Access to the preperitoneum is gained through a transverse abdominal incision two fingerbreadths above the pubic symphysis. The anterior rectus sheath is incised and the rectus abdominis is retracted medially to expose the posterior aspect of the sheath. The internal and external oblique muscles and the transversus abdominis muscle are also incised to reach the transversalis fascia (Fig. 37-25). The preperitoneal exposure and dissection is similar to other open preperitoneal techniques. Reconstruction of the inguinal floor is then enacted by suturing the transverse aponeurotic arch to Cooper's ligament and the iliopubic tract using interrupted sutures (Fig. 37-26). By suturing the transversalis fascia to Cooper's ligament, the femoral canal is obliterated. Around the internal ring, the leaflets of the transversalis fascia are sutured to the iliopubic tract to tighten the ring. The nature of the repair therefore specifically addresses femoral, direct, and indirect hernia defects. A mesh prosthesis is then implanted over the posterior aspect of the transversalis fascia and fixed to Cooper's ligament and above the iliopubic tract.
Kugel Repair

The Kugel repair aims to maximize on the preperitoneal approach while minimizing on the length of the skin and fascia incision.29 An oblique skin incision is made approximately 2 to 3 cm above the internal ring, which is estimated to be halfway between the anterior superior iliac spine and the pubic tubercle. The 3- to 4-cm incision is made one third lateral and two thirds medial between these two structures. The abdominal wall is opened using a series of muscle splitting incisions similar to open appendectomy. The external oblique aponeurosis is incised, the internal oblique muscle is bluntly divided, and the transversalis fascia is opened vertically for 3 cm, avoiding the internal ring. Blunt dissection is then performed within the preperitoneal space, deep to the inferior epigastric vessels. Cooper's ligament, the pubic tubercle, the iliac vessels, and the hernia sac are palpated to aid in anatomic identification. Hernia sac dissection and division, if necessary, is similar to other open preperitoneal approaches. Similarly, dissection along the spermatic cord should be carried proximally enough to accommodate a mesh that will adequately cover the internal ring. In Kugel's view, placing the patch sufficiently posterior is the most critical part of preventing recurrences; however, the preperitoneal pocket should be dissected only up to the point that it barely accepts the mesh prosthesis. The pocket should extend 3 cm medial to the pubic tubercle and lateral to the lateral extent of the transversalis incision. The procedure is inextricably linked to a specially designed mesh. The 8 x 12 cm mesh is composed of two sheets of polypropylene, with a slit in the anterior layer that accommodates a single digit or instrument during mesh positioning. The mesh can be deformed to fit through the small incision, yet the self-retaining single monofilament fiber around the periphery of the mesh allows the mesh to spring open, assuming its normal shape. Additional features of the mesh promote anchoring and incorporation of tissue into the mesh. The mesh is oriented parallel to the inguinal ligament, with three fifths sitting above the level of the inguinal ligament. The transversalis fascia is closed with a single absorbable stitch, incorporating the anterior surface of the mesh to prevent migration. The remainder of the wound is closed in successive layers using absorbable sutures. Kugel's experience of nearly 1500 patients demonstrates excellent recurrence rates (0.4%); however, these have not been reproduced owing to a steep learning curve associated with blind placement of the patch.30

Prolene Hernia System

The Prolene hernia system technology was constructed to take advantage of the benefits of the anterior and preperitoneal repair using an open approach. The mesh consists of two large flaps (an onlay and an underlay patch) with an intervening connector (Fig. 37-27). The underlay is positioned in the preperitoneal space while the overlay rests along the floor of the inguinal canal. Exposure of the inguinal canal is identical to standard open approaches. The preperitoneal space is entered according to the site of the defect. Indirect hernia sacs are dissected from the spermatic cord and sponge dissection of the preperitoneal space is subsequently performed through the internal ring. In the case of direct defects, the transversalis fascia is opened to provide for preperitoneal dissection. The underlay portion of the mesh is then placed through the hernia defect, thereby overlapping direct, indirect, and femoral site defects. The overlay flap reinforces the inguinal floor similar to a tension-free repair. Only the anterior layer of the mesh is secured, using three to four interrupted sutures to the pubic tubercle, inguinal ligament, and internal oblique muscle. As well, the overlay flap contains a slit to accommodate the spermatic cord. The bilayer connector prevents mesh migration and ensures correct positioning. The greatest advantage to this technique is that it adds a preperitoneal reinforcement to an otherwise open tension-free repair
Laparoscopic

Laparoscopic inguinal hernia repairs capitalize on the preperitoneal approach using a series of small incisions. The predominant techniques include transabdominal preperitoneal (TAPP) and totally extraperitoneal (TEP) repair, with intraperitoneal only mesh (IPOM) performed the least. The operating room setup is identical for both TAPP and TEP procedures. Mobilization of intra-abdominal and preperitoneal contents is optimally achieved by placing the patient in a Trendelenburg position. To this end, the monitors are placed at the foot of the bed, allowing the surgeon and assistant to view the procedure in a direct line of sight with instrumentation. The surgeon generally is positioned on the contralateral side to the hernia in question, although bilateral hernias can be repaired from either side. An assistant will occupy a position opposite the surgeon. The patient's arms are tucked at their sides and efforts must be made to adequately secure the patient during mobilization to the Trendelenburg position. Before performing the surgical prep, the bed should be tested to ensure the patient is fully secured and can hemodynamically tolerate being in Trendelenburg during the procedure. The scrub nurse and instrumentation table can be positioned on either side of the bed or at the foot of the bed. Figure 37-28 demonstrates a typical operating room setup for laparoscopic inguinal hernia.
Emergent

The indications for emergent inguinal hernia repair are incarcerated and strangulated inguinal hernias, as well as sliding hernias. By definition, an incarcerated hernia is one that cannot be reduced. Reasons for incarceration include a large amount of intestinal contents within the hernia sac, dense and chronic adhesions of hernia contents to the sac, and a small neck of the hernia defect in relation to the sac contents. The common factor that predisposes these aforementioned hernia syndromes to emergent operation is compromise of intestinal contents.

An incarcerated inguinal hernia without the sequelae of a bowel obstruction is not necessarily a surgical emergency. However, once the patient demonstrates bowel obstruction secondary to incarceration or a sliding inguinal hernia, operative intervention becomes expedited. Patients will often present with vomiting, constipation, obstipation, a distended abdomen, or combination thereof. In a sliding hernia, only one wall of a hollow viscus is present within the hernia sac. Although the lumen of the intestine is initially patent, strangulation of the knuckle of bowel may progress to localized edema and subsequent obstruction of the entire lumen. Less commonly, a sliding hernia will result from a portion of the bladder present within the hernia.

The most common presentation of small-bowel obstruction is usually secondary to previous operation and presence of adhesions. However, in the case of a patient with small-bowel obstruction and virgin abdomen, the diagnosis of carcinoma and inguinal hernia incarceration should be considered first. Physical examination is generally directed to the affected abdomen; however, the inguinal regions must be examined to rule out the presence of an incarcerated hernia. In the case of an ambiguous physical examination, radiologic evaluation such as CT should be considered early to define the source of obstruction. Failing this, diagnostic laparoscopy should be undertaken with the dual aim of diagnosing and alleviating the source of obstruction.

For known incarcerated hernias, reduction should be attempted before definitive surgical intervention. Hernias that are not strangulated and do not reduce with gentle pressure should undergo taxis. The patient is sedated and placed in a Trendelenburg position. The hernia sac is grasped with both hands, elongated, and then milked back through the hernia defect. Pressure applied to the most distal portion of the sac will cause the contents to mushroom and prevent reduction. Before attempting taxis, the patient should be made aware of potential surgery in the case of failure of the maneuver. Laparoscopy can be considered initially in the algorithm of treatment; however, most surgeons would prefer to approach incarcerated hernias with a conventional open approach.

If the blood supply to incarcerated contents becomes compromised, an incarcerated hernia becomes a strangulated hernia. These pose a significant risk to life because the strangulated contents are ischemic and may quickly lose viability. Clinical signs that indicate strangulation include fever, leukocytosis, and hemodynamic instability. The hernia bulge usually is very tender, warm, and may exhibit red discoloration. Taxis should not be applied to strangulated hernias as a potentially gangrenous portion of bowel may be reduced into the abdomen without being addressed. Before proceeding with surgery, the patient should be hemodynamically resuscitated with electrolytes, undergo nasogastric tube placement, and consideration should be given to early prophylactic IV antibiotics. Strangulated inguinal hernias should be approached using a conventional open technique. Once the hernia sac is encountered, efforts must be made to control it and prevent its inadvertent reduction into the abdominal cavity. The sac is opened to assess the viability of its contents. If viable, the contents are reduced intra-abdominally. If viability is in question, the hernia defect is expanded to alleviate the pressure on the intestinal vasculature and allow the intestine to be mobilized into the operative field. The bowel is then wrapped in warm wet towels and reassessed. Bowel viability can be assessed by bowel color, temperature, presence of peristalsis, and the Woods fluorescein test. Entrapped bowel within a femoral hernia may necessitate division of the inguinal ligament to provide for reduction and mobilization of the bowel. If the bowel is clearly ischemic and nonrecoverable, a decision must be made to resect the affected intestinal portion using the groin incision or perform a lower midline incision to increase exposure. Ideally, the ischemic portion is resected and viable portions are anastomosed to restore intestinal continuity. If the procedure becomes clean-contaminated through the resection of bowel, or if the intestine has been significantly compromised, repair of the hernia should proceed without the use of prosthetics, for fear of contamination and infection of the mesh.

Not uncommonly, an incarcerated or strangulated inguinal hernia may reduce with the administration of general anesthesia. A suspected strangulated hernia sac that reduces inadvertently during anesthesia induction, or before visual inspection by the surgeon, usually necessitates the conversion of the procedure to a laparotomy or laparoscopy to fully assess the bowel for viability. The consequences of a retained portion of ischemic bowel may lead to dire consequences for the patient's life.

Rarely, a surgeon will discover that upon entering the inguinal canal during emergent hernia treatment that no inguinal hernia exists. In these situations, strong consideration should be given to the presence of a femoral hernia. The femoral canal, located inferior to the medial inguinal ligament, is assessed for presence of an incarcerated or strangulated hernia.




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