Hernia

A hernia is the protrusion of an organ or tissue out of the body cavity in which it normally lies.

The most common hernias, by a generous margin, are inguinal hernias, both direct and indirect. Inguinal hernias are hernias involving a defect in the inguinal canal (in the lower abdomen). Inguinal hernias are more common in males than females.

Indirect inguinal hernias are more common in the young as it is due to a congenital defect in the processes vaginalis whilst direct inguinal hernias are more common in the elderly as they are cause by mechanical breakdown of the fascia over many years.

Terms used to describe a hernia:
reducible - the hernial contents can be returned to their normal site
irreducible
incarcerated - a.k.a. irreducible; the contents are fixed within the hernial sac
strangulated - incarcerated hernia with ischaemia of contents; often associated with signs and symptoms of intestinal obstruction
complete hernia - hernia sac and contents protrude all the way through the defect
incomplete hernia - hernial contents do not protrude completely

Types of hernias
Common or important hernia types in bold.

• sliding hernia - the hernia sac is partially formed by the wall of a viscus
• Littre's hernia - hernia involving a Meckel's diverticulum
• Spigelian hernia - hernia through the linea semilunaris (spigelian fascia); a.k.a. spontaneous lateral ventral hernia
• internal hernia - hernia into or involving an intraabdominal structure
• obturator hernia - hernia through obturator canal
• lumbar hernia
  • Petit's hernia - hernia through Petit's triangle (inferior lumbar triangle)
  • Grynfeltt's hernia - hernia through Grynfeltt-Lesshaft triangle (superior lumbar triangle)
• pantaloon hernia
• incisional hernia - hernia through an incisional site, most often caused by a wound infection
• ventral hernia
• Richter's hernia - incarcerated or strangulated hernia involving only one sidewall of the bowel. can result in bowel perforation through ischaemia without causing bowel obstruction.
• epigastric hernia - hernia through the linea alba above the umbilicus
• umbilical hernia - hernia through the umbilical ring, associated with ascites, pregnancy and obesity
• intraparietal hernia
• femoral hernia - hernia through the femoral ring
• Hesselbach's hernia
• Bochdalek's hernia
• Morgagni's hernia
• propertitoneal hernia
• Cooper's hernia
• inguinal hernias
  • direct inguinal hernia
  • indirect inguinal hernia
• hiatus hernia (hiatal hernia) - hernia of the stomach upwards through the esophageal hiatus

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Reference: Surgical recall, 2nd edition, by Lorne. H. Blackbourne, published by Lippincott Williams & Wilkins