(1)
Department of Surgery Division of Surgical Oncology, Icahn School of Medicine at Mount Sinai, New York, NY, USA
Introduction
An inguinal hernia is a defect in the abdominal wall through which bowel or other abdominal organ protrudes, dragging along with it the peritoneal lining as the hernia sac (Figs. 23.1–23.3). This defect can either be congenital, or it can be an acquired weakness which develops over time.
Fig. 23.1
Illustration of a right inguinal hernia containing small bowel [Reprinted from Freundlich RE, Hawes LT, Weldon SA, Brunicardi FC. Laparoscopic repair of an incarcerated right indirect sliding inguinal hernia involving a retroperitoneal ileum. Hernia 2011; 15(2): 225-227. With permission from Springer Verlag]
Fig. 23.2
CT scan image of a patient with a left inguinal hernia; bowel with oral contrast is seen within the hernia sac
Fig. 23.3
CT scan image of a patient with bilateral inguinal hernias. The right side is a sliding hernia containing bladder wall, the left side contains fluid and omentum
Indirect inguinal hernias, are congenital hernias caused by the persistence of the processus vaginalis. The testicle descends through this tract from the abdomen into the scrotum. This tract normally fuses closed in the third trimester, if it remains patent, however, bowel can herniate out the inguinal canal. In these indirect hernias, the hernia sac is found lateral to the inferior epigastric vessels, along the same path as the spermatic cord—or round ligament in females.
Direct inguinal hernias are acquired hernias caused by increased intra-abdominal pressure and/or weakness of the abdominal wall. Rather than passing through the internal ring and following the course of the spermatic cord, the hernia sac protrudes directly through the anterior abdominal wall, and therefore is found medial to the epigastric vessels. Causes of increased intra-abdominal pressure that lead to hernia formation include chronic cough, pregnancy, ascites, and constipation or prostatic hypertrophy associated with the need to strain. Weight lifting, with its frequent Valsalva maneuvers, can also cause direct hernias.
Although in the past every patient with an inguinal hernia was recommended to have surgical repair, watchful waiting is now an acceptable alternative in individuals who are completely asymptomatic. The most pressing reason to a repair hernia is to avoid the possible complication of incarceration or strangulation. An incarcerated hernia is one where bowel becomes trapped within the hernia sac. This often leads to bowel obstruction due to the acute angulation caused at the neck of the hernia defect. Although the bowel is trapped, it still retains a normal blood supply and is viable. However, as edema and congestion develop, the bowel within an incarcerated hernia can become compromised. If the bowel becomes ischemic, this is known as a strangulated hernia. Strangulation is a surgical emergency, because if the threatened bowel is not released, gangrene and perforation will develop. Strangulated hernias often present with bowel obstruction accompanied by clinical signs such as fever, tachycardia, and leukocytosis. On physical examination, the site of a strangulated hernia may be erythematous and tender. While an attempt may be made to reduce an incarcerated hernia, a suspected strangulated hernia should never be reduced. Operative exploration is imperative to assess the viability of the bowel and perform resection if indicated.
Surgical Technique
The repair of inguinal hernias has a long, complex history and the various techniques used are the subject of entire textbooks. Similarly the anatomy of the inguinal canal is challenging, and is made more difficult by the many eponyms used to name structures. An intentionally simplified description of the most commonly seen anatomy and techniques are presented here (Fig. 23.4).
Fig. 23.4
Simplified surgical anatomy during inguinal herniorrhaphy: spermatic cord, vas deferens, ilioinguinal nerve, conjoint tendon, shelving edge, inguinal ligament, mesh, internal ring, and pubic tubercle
For open inguinal herniorrhaphy, an incision is made in the skin above and parallel to the inguinal ligament. This is carried down through Scarpa’s fascia. At this level, one or two superficial epigastric veins are often seen, these are ligated. The aponeurosis of external oblique muscle is encountered next; this layer is opened along the line of its fibers and is carried through the external ring, opening it entirely. The underlying ilioinguinal nerve should be identified and carefully protected. The spermatic cord is encircled and elevated. If the patient has an indirect hernia, a hernia sac will be seen coming through the internal ring and will lie on the anteriomedial aspect of the cord. This sac may be opened or simply reduced, per surgeon preference. If the patient has a direct hernia, a weak floor of the inguinal canal will be noted, with the hernia bulging up into the field.
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