A hernia is a protrusion of usually a loop of bowel or a tissue through an opening in the wall of the abdominal cavity in which the bowel lies. Hernias are one of the most common conditions requiring surgery. A hernia is a protrusion of usually a loop of bowel or a tissue through an opening in the wall of the abdominal cavity in which the bowel lies. Hernias can occur in men and women of all ages and in children (see Pediatric Hernia Repair). Hernias can develop around the navel, in the groin, or any place where you may have had a surgical incision. Some hernias are present at birth. Others develop slowly over a period of months or years. Hernias may also come on quite suddenly.

Anatomy

• The abdominal wall in the groin area is made up of different structures going from deep to superficial layers (Figure 1 and 2):
  
  1. Peritoneum - the lining of the abdominal cavity (becomes the hernia sac)
     
  2. Subperitoneal fat - fat beneath the peritoneum
     
  3. Transversalis fascia - sheet of fibrous tissue that envelops the peritoneum
     
  4. Transversus abdominis muscle
     
  5. Internal oblique muscle
     
  6. External oblique muscle
     
  7. Subcutaneous fat
     
  8. Skin

Figure 1 - Layers of the abdominal wall, inguinal canal and their relations to the spermatic cord and testies. © C. Salici	Figure 2 - Anatomy of the inguinal canal and relationship to the pelvic bone. © C. Salici