An inguinal hernia is an opening in the muscle of the groin in which a portion of the intestine (or ovary, in girls), can pass through.
It may be large or small, and usually appears as a lump or swelling in the groin or scrotum in boys, or in the labia in girls.
An umbilical hernia develops when the muscles in the abdomen, around the belly button, do not fully close before birth, and some intestine protrudes into the opening.
The operation is a perfectly safe procedure and will not cause a male to become sterile. Fixing a hernia can prevent damage to the testicle.