Blueprints Surgery, 5th Edition

Part II - Gastrointestinal and Abdominal

Chapter 11

Hernias

HERNIAS

A hernia occurs when a defect or weakness in a muscular or fascial layer allows tissue to exit a space in which it is normally contained. Hernias are categorized as reducible, incarcerated, or strangulated. Reducible hernias can be returned to their body cavity of origin. Incarcerated hernias cannot be returned to their body cavity of origin. Strangulated hernias contain tissue with a compromised vascular supply. These are particularly dangerous because they lead to tissue necrosis. If the bowel is involved, this can progress to perforation, sepsis, and death.

EPIDEMIOLOGY

Between 500,000 and 1,000,000 hernia repairs are performed each year. Five percent of people have an inguinal hernia repair during their lifetime. Half of all hernias are indirect inguinal, and one fourth are direct inguinal. In decreasing incidence are incisional and ventral (10%), femoral (6%), and umbilical hernias (3%). Obturator hernias are rare. Indirect inguinal hernias are the most common in both males and females; overall, hernias have a five:one male predominance. Femoral hernias are more common in females than in males.

INGUINAL HERNIAS

ANATOMY

The abdominal contents are kept intraperitoneal by fascial and muscular layers: the innermost layer is the transversalis fascia, with the three more superficial musculofascial layers being the transversus abdominis, the internal oblique, and the external oblique (see Color Plate 8).

During normal development, the testes begin in an intra-abdominal position and descend through the internal ring, taking with them a layer of peritoneum that is stretched into a hollow tube called the processus vaginalis. This invagination of peritoneum, exiting through the deep and superficial inguinal rings and extending into the scrotum to where the testicle has terminated its descent, will result in an indirect inguinal hernia unless the following occurs: the tubular processus vaginalis must collapse upon itself, fusing opposing peritoneal surfaces and obliterating the tube into a cord-like structure. If this obliteration/fusion of the peritoneal layers does not occur completely, an indirect inguinal hernia will result (Fig. 11-1A).

A direct inguinal hernia results from a weakness in the abdominal wall (specifically, the transversalis) in the area just deep to the superficial ring where the spermatic cord exits the inguinal canal before traveling down into the scrotum (Fig. 11-1B). This area is medial to the epigastric vessels and is called Hesselbach triangle (defined as the edge of the rectus sheath medially, the inguinal ligament inferiorly, and the inferior epigastric vessels laterally; Fig. 11-2).

Progressive structural weakening and loss of integrity of the transversalis at this location allows bulging of the weakened abdominal wall through the area of Hesselbach triangle, the most medial aspect and back wall of the inguinal canal itself. Once the defect is large enough, bowel or other abdominal contents can protrude directly through the fascia and out the superficial ring. Direct inguinal hernias are typically seen in older individuals, whereas indirect inguinal hernias predominate in the pediatric population. Also, the

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external oblique, which inserts onto the pubic tubercle and bounds the external superficial ring, has no function in the pathogenesis of hernias.

HISTORY

Patients with reducible inguinal hernias describe an intermittent bulge in the groin or scrotum. Persistence of the bulge with nausea or vomiting raises concern for incarceration. Severe pain at the hernia site with nausea or vomiting may occur with strangulation.

PHYSICAL EXAMINATION

With the patient in a standing position, a fingertip is directed upward to find the superficial ring. This is facilitated in male patients by entering the loose scrotum at its base and following the course of the

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spermatic cord until the superficial ring is encountered. With the fingertip inserted into the ring, a bulge is felt in small hernias as the patient coughs or bears down (Fig. 11-3).

In larger hernias, the herniated sac can be palpated without the aid of Valsalva maneuvers. With the patient in the supine position, reducible hernias can be reduced into the abdomen, whereas incarcerated hernias cannot. Strangulated hernias are tender as a result of peritoneal inflammation. Abdominal distention is often encountered as a result of bowel obstruction.

TREATMENT

Traditionally, the simple presence of an inguinal hernia was indication enough for a surgeon to advise elective repair. Conventional thinking was that the benefit of preventing a hernia accident (i.e., acute incarceration with bowel obstruction or strangulation of abdominal contents) clearly outweighed the potential risks and complications of elective hernia repair. However, the natural history of untreated inguinal hernias and the risks they posed had never been precisely determined until recently. In 2006, a landmark clinical trial involving 720 men with minimally symptomatic inguinal hernias randomly assigned patients to either watchful waiting or surgery with standard open tension-free repair. The key study finding was that the rate of hernia accidents are extremely rare (1.8 per 1,000 patient-years), leading to the study's conclusion that, "A strategy of watchful waiting is a safe and acceptable option for men with asymptomatic or minimally symptomatic inguinal hernias. Acute hernia incarcerations occur rarely, and patients who develop symptoms have no greater risk of operative complications than those undergoing prophylactic hernia repair."

Modern hernioplasty is based on the idea of tension-free repair using an implantable biocompatible prosthe-sis to reconstruct the fascial hernia defect (Figs. 11-4 and 11-5). The superiority of the concept of mesh tension-free repair versus traditional nonmesh tension-producing repair was validated by a Cochrane Group review published in 2002. The use of mesh was found to significantly reduce the risk of hernia recurrence by an astounding 50% to 75%. Reducible inguinal hernias can be repaired on an elective basis depending on the degree of patient symptoms. Both open and laparoscopic techniques are acceptable, although a recent Veterans Affairs study (2004) showed a higher recurrence rate with laparoscopic repair (10%) when compared with open repair (4%) of primary hernias. The usual indications for laparoscopic repair are bilaterality and recurrence. Interestingly, the Veterans Affairs study showed the rates of recurrence after repair of recurrent hernias as being similar with laparoscopic versus open repairs (10.0% versus 14.1%). Inguinal hernias in adult men should typically be repaired with mesh to avoid recurrence. In women, the round ligament is ligated and the ring closed so mesh use is variable.

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When a hernia is not reducible with gentle pressure, a trial of Trendelenburg position, sedation, and more forceful pressure can be attempted. If the hernia is thought to be strangulated, then reduction is contraindicated, because reducing necrotic bowel into the abdomen may produce bowel perforation and subsequent lethal sepsis. Emergency surgery is indicated in this situation. A sample operative note for an inguinal hernia is provided in the Appendix.

UMBILICAL HERNIAS

Umbilical hernias occur at the umbilicus and are congenital. They result from incomplete closure of the fetal umbilical defect. Most resolve spontaneously by the age of 4 years.

EPIDEMIOLOGY

The incidence is 10% of Caucasians and 40% to 90% of African Americans.

HISTORY

The patient may have a bulge at the umbilicus.

TREATMENT

Indications for operation include incarceration, strangulation, or cosmetic concerns.

OTHER HERNIAS

Femoral hernias occur through the femoral canal, located below the inguinal ligament and defined by the femoral vein laterally, the inguinal ligament superiorly, the lacunar ligament medially, and Cooper ligament inferiorly.

Incisional hernias occur through a previous surgical incision. Ventral hernias occur in the midline along the linea alba, usually between the xiphoid and umbilicus. The herniation is through a weakness of the decussating fibers of the linea alba. Spigelian hernias are found at or below the junction between the vertically oriented semilunar line lateral to the rectus abdominus muscle and the transversely oriented arcuate line (linea semicircularis). A pantaloon hernia is a combined direct and indirect inguinal hernia where both hernias straddle each side of the inferior epigastric vessels and protrude like pant legs (pantaloon). Richter hernia occurs when a knuckle of bowel protrudes into a hernia defect, but only a portion of the circumference is involved and the bowel lumen remains patent. Typically, the result is gangrenous necrosis of the herniated tissue. A sliding hernia is any hernia that contains intra-abdominal organs. Internal hernias may occur in patients after abdominal operations when bowel gets trapped as a result of new anatomic relationships. Obturator hernias are typically found in thin, older adult women who present with bowel obstruction caused by small bowel herniation into the obturator canal. Obturator nerve compression by the hernia can result in paresthesias or pain radiating down the medial thigh (the Howship-Romberg sign). Littre hernia is any groin hernia that contains a Meckel's diverticulum.

Something that is not a hernia but is often confused as one is diastasis recti. An upper midline bulge develops when the patient performs a Valsalva maneuver, and herniation is suspected. On close physical examination, however, no actual defect or "hole" in the fascia is found. Rather, the linea alba has become attenuated and weak, resulting in widening of the distance between the rectus muscles. It is this thin, stretched linea alba that bulges out and mimics a large hernia. Surgical repair is not indicated.

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Key Points

• Hernias are extremely common. Inguinal hernias are the most common, and 5% of people require repair during their lifetime.
• Indirect inguinal hernias arising from a patent processus vaginalis are more common than direct hernias from abdominal wall weakness.
• Hernias that become incarcerated should be operated on urgently.
• Hernias that become strangulated are a surgical emergency.
• Umbilical hernias are congenital, more common in African Americans, and frequently resolve spontaneously.
• Diastasis recti is not a true herniation and does not require surgical repair.
• Modern hernioplasty is based on the principle of tension-free repair using an implantable biocompatible prosthesis to reconstruct the fascial hernia defect.