A hernia is the protrusion of a structure through the wall of the cavity containing it. In the context of this website, a hernia is simply the protrusion of the bowel through a hole or weakness in the muscle layer of the wall of the abdomen.

There are many different types of hernia, named according to the site of the weakness of the abdominal wall. All hernias may gradually increase in size over time. They can be asymptomatic but may cause symptoms of aching or pain. A lump may or may not be palpable. One of the key concerns is the risk of a hernia becoming obstructed or strangulated. The first signs of this are a sudden increase in pain and tenderness of the hernia. The swelling may increase in size and it may not be possible to reduce the hernia, that is to push the swelling back in.