A hernia is a bulge or protrusion of an organ through the structure or muscle that contains it. There are many different types of hernias.

The most familiar are those in which part of the intestines protrude through the abdominal wall. An inguinal hernia appears as a bulge in the groin. It can occur with or without pain. Inguinal hernias account for 80% of all hernias and are more common in men, in whom they may descend into the scrotum.

Most hernias result from a weakness in the abdominal wall that either develops or is present at birth. Any increase in pressure in the abdomen, such as coughing, straining, heavy lifting, or pregnancy, can help cause an abdominal hernia. Obesity or recent excessive weight loss, as well as aging and previous surgery, are also risk factors.

Most abdominal hernias appear suddenly when the abdominal muscles are strained. The person...