A hernia is a protrusion of an organ or part of an organ through a weak point or aperture in the surrounding structures. In those affecting the digestive system, a piece of bowel protrudes through a weak point in either the musculature of the anterior abdominal wall or an existing opening. It occurs when there are intermittent increases in intra- abdominal pressure,most common in men who lift heavy loads at work. The underlying causes of the abdominal wall weakness are unknown. Outcomes include:
- Spontaneous reduction, ie the loop of bowel slips back to its correct place when the intra-abdominal pressure returns to normal.
- Manual reduction,ie.by applying gentle pressure over the abdominal swelling.
- Strangulation,when reduction is not possible and the venous drainage from the herniated loop of bowel is obstructed,causing congestion,ischaemia and gangrene. In addition there is intestinal obstruction.
SITES OF HERNIAS.
INGUINAL HERNIA.The weak point is the inguinal canal,which contains the spermatic cord in the male and the round ligament in the female. It occurs more commonly in males and females.
FEMORAL HERNIA. The weak point is the femoral canal through which the femoral artery,vein and lymph vessels pass from the pelvis to the thigh.
UMBILICAL HERNIA. This weak point is the umbilicus where the umbilical blood vessels from the placenta entered the fetus before birth.
INCISIONAL HERNIA. This is caused by repeated stretching of fibrous tissue formed after previous abdominal surgery.
