A hernia can be compared to a failure of the side wall of a tire. The inner tube of the tire behaves like the organ and the side wall like the wall of the body cavity, which provides restraint. A weakness in the sidewall can develop a bulge that can become a gap, causing the inner tube to protrude and the tire to fail. Hernias can be painful at the site, a visible or palpable lump, or in some cases vague symptoms due to pressure on an organ that has “stuck” in the hernia and sometimes leads to organ dysfunction. Fat tissue usually enters a hernia first, but it may be followed or accompanied by an organ.
A hernia occurs when the contents of a body cavity swell out of the area in which it is normally contained. These contents, usually parts of the intestinal or abdominal fat, are enclosed in the thin membrane that naturally lines the inside of the cavity. Although the term hernia can be used to refer to bulges in other areas, it is most often used to describe abdominal hernias (hernias of the abdominal wall).
The femoral canal is the route through which the femoral artery, vein, and nerve exit the abdominal cavity to enter the thigh. Although usually a narrow space, it sometimes becomes large enough to allow abdominal contents (usually the intestines) to enter the canal. A femoral hernia causes a bulge just below the crease of the groin at about the middle of the thigh. Femoral hernias usually occur in women and are particularly at risk of becoming irreducible (unable to be pushed back) and strangling.
Signs and symptoms of a hernia
The hernia can be reduced early – the protruding structures can be gently pushed back to their normal location. However, if these structures cannot be returned to their normal location by manipulation, the hernia is said to be irreducible or trapped.
The vast majority of hiatus hernias are slippery and most of them are not associated with symptoms. The larger the inguinal hernia, the more likely it is that symptoms will develop. When slippery hiatus hernias cause symptoms, it is almost always gastroesophageal reflux disease (GERD) or its complications.
During the development of boys, the testes may descend through a hole in the abdomen into the scrotum. A similar opening may exist in girls, although the ovaries do not protrude beyond the abdomen. Usually, this hole closes before a baby is born. An inguinal hernia occurs when a bag protrudes through the opening and wall of the abdominal cavity.
About five in 100 children have hernias. Inguinal hernias in newborns and children result from weakness in the abdominal wall present at birth. Sometimes the hernia is not visible until a baby cries, coughs, or gets tired during a bowel movement. In an older child, a hernia is likely to be more obvious when the child coughs, gets tired during a bowel movement, or stands for a long time.
A hiatus hernia alone rarely causes symptoms – the pain and discomfort is usually due to reflux of stomach acid, air, or bile. Reflux is more likely to occur in hiatus hernia, although hiatus hernia is not the only cause of reflux.