The incidence of inguinal hernias in men has a bimodal distribution, which peaks:
Approximately 75% of abdominal wall hernias occur in the groin. The lifetime risk of inguinal hernia is 27% in men and 3% in women. Of inguinal hernia repairs, 90% are performed in men and 10% in women. The incidence of inguinal hernias in men has a bimodal distribution, with peaks before the first year oflife and after age 40. Abramson demonstrated the age dependence of inguinal hernias in 1978. Those between ages 25 and 34 years had a lifetime prevalence rate of 15%, whereas those aged 75 years and over had a rate of 47% (Table below). Approximately 70% of femoral hernia repairs are performed in women; however, inguinal hernias are five times more common than femoral hernias. The most common subtype of groin hernia in men and women is the indirect inguinal hernia.
Inguinal hernia prevalence by age:
The two types of collagen found to exist in a decreased ratio of the skin of inguinal hernia patients are:
Epidemiologic studies have identified risk factors that may predispose to a hernia. 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 revealed disaggregated collagen tracts with decreased collagen fiber density in hernia patients' skin. Collagen disorders, such as Ehlers-Danlos syndrome, are also associated with an increased incidence of hernia formation (Table below). Recent studies have found an association between concentrations of extracellular matrix elements and hernia formation. Although a significant amount of work remains to elucidate the biologic nature of hernias, current evidence suggests they have a multifactorial etiology with both environmental and hereditary influences.
Connective tissue disorders associated with groin herniation:
According to the Nyhus classification system that categorizes hernia defects by location, size, and type, type IIIC represents:
Nyhus classification system:
Taxis:
Incarceration occurs when hernia contents fail to reduce; however, a minimally symptomatic, chronically incarcerated hernia may also be treated nonoperatively. Taxis should be attempted for incarcerated hernias without sequelae of strangulation, and the option of surgical repair should be discussed prior to the maneuver. To perform taxis, analgesics and light sedatives are administered, and the patient is placed in the Trendelenburg position. The hernia sac is elongated with both hands, and the contents are compressed in a milking fashion to ease their reduction into the abdomen.
The indication for emergent inguinal hernia repair is impending compromise of intestinal contents. As such, strangulation of hernia contents is a surgical emergency. Clinical signs that indicate strangulation include fever, leukocytosis, and hemodynamic instability. The hernia bulge is usually warm and tender, and the overlying skin may be erythematous or discolored. Symptoms of bowel obstruction in patients with sliding or incarcerated inguinal hernias may also indicate strangulation. Taxis should not be performed when strangulation is suspected, as reduction of potentially gangrenous tissue into the abdomen may result in an intra-abdominal catastrophe. Preoperatively, the patient should receive fluid resuscitation, nasogastric decompression, and prophylactic intravenous antibiotics.
A hernia sac that extends into the scrotum may:
In cases where the viability of sac contents is in question, the sac should be incised, and hernia contents should be evaluated for signs of ischemia. The defect should be enlarged to augment blood flow to the sac contents. Viable contents may be reduced into the peritoneal cavity, while nonviable contents should be resected, and synthetic prostheses should be avoided in the repair. In elective cases, the sac may be amputated at the internal inguinal ring or inverted into the preperitoneum. Both methods are effective; however, patients undergoing sac excision had significantly increased postoperative pain in a prospective trial. Dissection of a densely adherent sac may result in injury to cord structures and should be avoided; however, sac ligation at the internal inguinal ring is necessary in these cases. A hernia sac that extends into the scrotum may require division within the inguinal canal, as extensive dissection and reduction risks injury to the pampiniform plexus, resulting in testicular atrophy and orchitis. At this point, the inguinal canal is reconstructed, either with native tissue or with prostheses. The following sections describe the most commonly performed types of tissue-based and prosthetic-based reconstructions.
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