Hernia

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Basics

Description

Areas of weakness or disruption of the abdominal wall through which structures can pass

  • Types
    • Inguinal
      • Direct: acquired; herniation through defect in transversalis fascia of abdominal wall medial to inferior epigastric vessels; increased frequency with age as fascia weakens
      • Indirect: congenital; herniation lateral to the inferior epigastric vessels through internal inguinal ring into inguinal canal. A “complete hernia” descends into the scrotum, an “incomplete hernia” remains in 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 descending through the femoral canal deep to the inguinal ligament; has a narrow neck and 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 defect in abdominal wall fascia due to collagen deficiency disease
    • Umbilical: defect at umbilical ring
    • Epigastric: protrusion through the middle line above the level of the umbilicus
    • Spigelian hernia: herniation through Spigelian line (lateral border of the rectus abdominis) for a lateral ventral hernia result
    • Sports hernia (not a true hernia): strain or tear of soft tissue of groin or lower abdomen
    • Others: obturator, sciatic, perineal
  • Definitions
    • Reducible: Extruded sac and its contents can be returned to intra-abdominal position spontaneously or with gentle 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., right side–cecum, left side–sigmoid colon).

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

Pregnancy Considerations
  • 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

Incidence
  • 75–80% groin hernias: inguinal and femoral
  • 2–20% incisional/ventral, depends if prior surgery was associated with infection or contamination
  • 3–10% umbilical, considered congenital
  • Groin
    • 6–27% lifetime risk in adult men
    • Two peaks: most inguinal hernias present before 1 year of age or after 55 years of age
    • ~50% of children <2 years of age have a patent processus vaginalis, decreasing to 40% after age 2 years. Only between 25% and 50% are clinically significant.
    • Inguinal hernia in <5% of newborns male-to-female ratio 10:1
    • Increased incidence in premature infants
    • 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: male = female
  • Umbilical: 10–20% of newborns; most close by age 5 years

Prevalence
  • Groin and inguinal hernias are more prevalent in men; femoral and umbilical more prevalent in women
  • Most inguinal hernias are indirect in men and women.
  • Incisional/ventral hernias (IVH) are more prevalent in smokers and obese individuals.

Etiology and Pathophysiology

Loss of tissue strength and elasticity (especially with aging or congenital defect in abdominal fascia) results in a fascial defect of the abdominal wall. Most pediatric hernias are congenital (e.g., patent processus vaginalis). Most adult hernias are a result of acquired weakness in the tissues of the anterior abdominal wall.

Genetics
No known genetic pattern

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.

Commonly Associated Conditions

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

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