What Is It?

A hernia occurs when part of an internal organ or body part protrudes through an opening into another area where it shouldn't. Many different types of hernias can develop, but the most common occur when a piece of the intestine pokes through a weak area in the wall of the abdomen. This causes an abnormal bulge under the skin of the abdomen, usually near the groin or the navel.

Each type of hernia has a particular location and tends to occur for different reasons. Some hernias are present at birth while others develop in adulthood. Many hernias grow bigger when pressure frequently builds up in the abdomen, for example during straining, lifting or coughing.

• Inguinal hernia - A piece of intestine pokes through a weakness in the inguinal canal, a natural passageway through the abdominal wall near the groin. In males, it is the normal route for the testes to descend into the scrotum before birth. Inguinal hernias account for 75% of all hernias, and are 5 times more common in males than females. They usually are present at birth, but can develop in adults.

• Femoral hernia - A piece of intestine pokes through the passage that normally is used by large blood vessels (the femoral artery and vein) when they pass between the abdomen and the leg. This type of hernia causes a bulge in the upper thigh, and is more common in women than men.

• Epigastric, or ventral, hernia - A piece of intestine bulges through a weakness in abdominal muscles between the navel and breastbone. Most people with ventral hernias are men, usually between ages 20 and 50.

• Umbilical hernia - A piece of intestine bulges through the abdominal wall next to the navel. The area of weakness in the abdominal wall can be very small (less than half an inch) or it can be as large as 2 inches to 3 inches. Umbilical hernias are common in newborns, but may disappear gradually over time.

• Parumbilical hernia - This looks like an umbilical hernia, but it is not present at birth. Parumbilical hernias often are caused by long-standing strain on the abdominal muscles, which commonly occurs in people who are overweight, or in women who have been pregnant many times.

• Incisional hernia - A piece of the intestine bulges through a weakness in the abdominal wall in an area where surgery has been done previously.

• Hiatal hernia - This hernia involves the stomach rather than the intestines. A piece of the stomach slips through a normal opening in the diaphragm and passes upward into the chest.