A hernia occurs when a portion of tissue in your body bulges into or penetrates a weakened muscle area. Theoretically, hernias can happen anywhere in your body, but most occur in the abdomen between the rib cage and the groin.
There are several types of hernias:
- Hiatus or diaphragmatic hernias occur when a piece of your stomach protrudes into the diaphragm (the muscle that separates the chest region from the abdominal area) via the opening through which the esophagus (food tube) passes into the stomach.
Hernias may also occur in infancy because of a weakness in the abdominal wall. They occur in about 5% of full-term infants and up to 30% of premature babies.
- Inguinal or groin hernias occur when part of the abdominal contents (usually part of the intestine or a piece of bowel) protrudes into the groin area.
Men are 10 times as likely as women to get them. They often occur after age 50 (on one side of the groin or both) and account for approximately 10% of all hospital admissions for surgery.
- Umbilical hernias are similar to inguinal hernias but are found in the area of the umbilicus (the navel or belly button area).
- Incisional hernias occur when a piece of intestine protrudes through a weakness in the abdominal wall in an area where surgery has been performed.
- Femoral hernias occur when a piece of intestine protrudes though the passage that is normally used by large blood vessels as they pass between the abdomen and leg.
- Paraesophageal hernias are very rare, but can be life threatening because in some cases they can cause the entire stomach to slip into the chest cavity.
The cause of some hernias cannot be pinpointed, but many result from increased pressure within the abdomen, a weak spot in the abdominal wall, or a combination of the two.
In adults, hiatus hernias commonly develop in pregnant women and overweight people due to the increased pressure on the abdominal wall.
In men, an inguinal hernia will commonly develop in the groin, specifically in a region called the inguinal canal. This is where the spermatic cord and blood vessels to the testicles pass out of the abdominal cavity and into the scrotum. A weakness in the abdominal tissues at this point can allow a loop of bowel to pass out of the abdomen by following the path of the spermatic cord (indirect inguinal hernia) or between the opening into the inguinal canal and the pubic bone (direct inguinal hernia).
In women, inguinal hernias are rare, but can develop where the tissue that binds the uterus exits from the abdomen and joins with the tissue surrounding the vaginal opening.
Umbilical hernias may be present at birth. In adults, they may develop when there is a weakness in the tissue in the umbilical area combined with increased pressure on the abdominal wall.