Description

Hernias are areas of weakness or frank disruption of the fibromuscular tissues of the body wall through which intracavity structures pass:

• Types:
  • Inguinal:
    • Direct inguinal: Acquired; herniation through defect in transversalis fascia of abdominal wall medial to inferior epigastric vessels; increased frequency with age as fascia weakens
    • Indirect inguinal: Congenital; herniation lateral to the inferior epigastric vessels, through internal inguinal ring into inguinal canal. A “complete hernia” is one that descends into the scrotum, whereas an “incomplete hernia” remains within the inguinal canal.
  • Pantaloon: Combination of direct and indirect inguinal hernia with protrusion of abdominal wall on both sides of the epigastric vessels
  • Femoral: Herniation that descends through the femoral canal deep to the inguinal ligament. Because of the narrow neck of a femoral hernia, this type of hernia is especially prone to incarceration and strangulation.
  • Incisional or ventral: Herniation through a defect in the anterior abdominal wall at the site of a prior surgical incision
  • Congenital: Herniation through fascial defect in abdominal wall, secondary to collagen deficiency disease
  • Umbilical: Defect occurs at umbilical ring tissue. Epigastric: Protrusion through the linea alba above the level of the umbilicus. These may develop at exit points of small paramidline nerves and vessels, or through an area of congenital weakness in the linea alba.Interparietal (e.g., Spigelian hernia): Hernia sac insinuates itself between layers of the abdominal wall; strangulation common, often mistaken for tumor or abscess Other: Obturator, sciatic, perineal
• Definitions:
  • Reducible: Extruded sac and its contents can be returned to original intra-abdominal position, either spontaneously or with gentle manual manipulation.
  • Irreducible/incarcerated: Extruded sac and its contents cannot be returned to original intra-abdominal position.
  • Strangulated: Blood supply to hernia sac contents is compromised.
  • Richter: Partial circumference of the bowel is incarcerated or strangulated. Partial wall damage may occur, increasing potential for bowel rupture and peritonitis.
  • Sliding: Wall of a viscus forms part of the wall of the inguinal hernia sac (i.e., R-cecum, L-sigmoid colon).

Geriatric Considerations
Abdominal wall hernias increase with advancing age, with significant increase in risk during surgical repair.

• Increased intra-abdominal pressure and hormone imbalances with pregnancy may contribute to increased risk of abdominal wall hernias.
• Umbilical hernias are associated with multiple, prolonged deliveries.

Epidemiology

• 75–80% groin hernias: Inguinal and femoral
• 2–20% incisional/ventral, depending on whether a prior surgery was associated with infection or contamination
• 3–10% umbilical, considered congenital
• 1–3% other
• Groin:
  • 6–27% lifetime risk in adult men
  • 2-peak theory: Most inguinal hernias present before 1 year of age or after 55 years
  • ~50% of children under 2 will have a patent processus vaginalis, decreasing to 40% after age 2. Only between 25% and 50% will become clinically significant.
  • Inguinal hernia found in <5% of newborns, but M:F ratio is 10:1
  • Increased incidence in premature infants (1)[B]
  • Increased incidence in patients with abdominal aortic aneurysms
  • Femoral <10% of all groin hernias, 40% present as a surgical emergency
• Incisional/ventral: ~10–23% of abdominal surgeries complicated by an incisional hernia, most common in upper midline incisions. Incidence ratio M:F is 1:1.
• Umbilical: 10–20% of newborns (2). Most close by 5 years of age.

• Groin and inguinal hernias are more prevalent in men.
• Femoral and umbilical hernias more prevalent in women.
• Most inguinal hernias are indirect in both genders.
• Incisional/ventral hernias are more prevalent in obese persons as well as in smokers. The opposite may be true for inguinal hernias (3)[C].

Risk Factors

• Increased abdominal pressure, coughing, heavy lifting, constipation, pregnancy, ascites, prostatism, obesity, advancing age (loss of tissue turgor), smoking, steroid use, low birth weight, prematurity
• Age: Femoral and scrotal hernias, along with recurrent groin hernias, are associated with increased risk for acute hernia surgery (4).

Genetics
No known genetic pattern

Pathophysiology

Loss of tissue strength and elasticity, especially with aging or congenital defect in abdominal fascia

Etiology

A defect in the fascia of the abdominal wall. Most pediatric hernias are congenital defects (e.g., patent processus vaginalis), whereas most adult hernias are a result of acquired weakness in the tissues of the anterior abdominal wall.

Commonly Associated Conditions

Obesity, chronic obstructive pulmonary disease, multiple abdominal surgeries, pregnancy, advanced age, Ehlers-Danlos syndrome, Marfan syndrome, PKD, osteogenesis imperfecta, Down syndrome, abdominal aortic aneurysm