DESCRIPTION

Inguinal hernia is a protrusion of intra-abdominal contents into, and often through, the inguinal canal.

• Inguinal hernia is one of the most frequent problems requiring elective surgical intervention in children.
• Thought to be secondary to the relation of the processus vaginalis with testicular descent

EPIDEMIOLOGY

• Incidence of 3–5% in term infants, 13% in infants born at <33 weeks’ gestation, and 30% in infants weighing <1,000 g
• Laterality
  • Left processus vaginalis involution precedes that of the right
  • Clinical presentation is on the right side in 60% of cases, on the left side in 30%, and bilateral in 10%.
• Patent processus vaginalis does not always result in inguinal hernia.
  • Estimated childhood risk of developing an inguinal hernia if there is a patent processus vaginalis is between 25% and 50%.
• Significantly more common in boys (90% of cases)
• Has a familial tendency

RISK FACTORS

• Prematurity
• Urologic conditions:
  • Cryptorchidism
  • Hypospadias
  • Epispadias
  • Bladder exstrophy
• Abdominal wall defects:
  • Gastroschisis
  • Omphalocele
  • Eagle-Barrett syndrome
• Conditions that increase intra-abdominal pressure (e.g., ascites, peritoneal dialysis, ventriculoperitoneal shunt)
• Cystic fibrosis
• Connective tissue disease:
  • Marfan syndrome
  • Ehlers-Danlos syndrome
• Disorders of sex development (DSD)
• Mucopolysaccharidoses
• Family history

PATHOPHYSIOLOGY

• Indirect inguinal hernia: majority in pediatric patients
  • Descent of the testes from the embryologic retroperitoneum begins early in gestation; in the male fetus, it occurs between weeks 8 and 15.
  • Final descent of the testes into the scrotum occurs late in gestation between weeks 28 and 36.
  • After the testes reach the scrotum, the path of peritoneum through which the testicle passed (processus vaginalis) begins to obliterate spontaneously, leaving only a small potential space adjacent to the testes (tunica vaginalis).
  • In the female fetus, the gubernaculum persists as the ovarian round ligament and passes thorough the inguinal canal. When the processus vaginalis remains open, it is identified as the canal of Nuck.
  • Incomplete obliteration of the processus vaginalis leaves a sac of peritoneum extending from the internal inguinal ring to the scrotum or labium majus, through which an inguinal hernia may or may not develop.
• Direct inguinal hernia
  • Rare in children
  • Results from either a congenital or acquired/traumatic weakness or tear in abdominal wall fascia
• Other types of inguinal hernias
  • Sliding hernia occurs when one wall of the hernia is composed of abdominal viscera (bladder, colon, adnexa).
  • Richter hernia results from the herniation of only a part of the bowel wall. If this hernia is incarcerated/strangulated, it may progress to bowel perforation without obstruction.
  • Hernia of Littre is when a Meckel diverticulum is found within the hernia sac.
  • Amyand hernia is an inguinal hernia in which the appendix is included within the hernia sac.