When part of an organ protrudes through an abnormal opening or in an abnormal way, this is called a hernia. A groin (inguinal) hernia occurs when part of the intestine bulges through a weak spot in the abdominal wall at the inguinal canal. The inguinal canal is a passageway through the abdominal wall near the groin. Inguinal hernias are up to 10 times more common in men than in women. About one in four men develop a hernia at some point in life. There are two types of inguinal hernias:

Indirect inguinal hernia - This occurs when the internal opening of the inguinal canal, which usually closes around the time of birth, remains open. This allows a portion of the intestine to slip through the inguinal canal. These hernias often are diagnosed within the first year of life, but may not show up until adulthood. This condition affects between 1% and 5% of normal newborns and up to 10% of premature infants.

Direct inguinal hernia - This occurs when a portion of the intestine protrudes through a weakness in the abdominal muscles along the wall of the inguinal canal. These are common in adults, but rarely occur in children. 

In adults, direct and indirect inguinal hernias look and feel about the same. They can occur on one or both sides of the groin. Your doctor may not know which type of hernia you have until surgery is performed. However, both types of hernias are treated in a similar manner. A type of hernia called a femoral hernia can appear similar to an inguinal hernia. Femoral hernias are much more common in women than in men. They may cause a lump that appears just below the groin and extends into the upper portion of the thigh. In a femoral hernia, a portion of the intestine protrudes through the passage that is normally used by large blood vessels (the femoral artery and vein) when they pass between the abdomen and the leg. Femoral hernias are most common in older, overweight women.