A hernia is a lump or protrusion of an organ (usually the small bowel or fatty material) through a weakness or opening in the muscle wall of the abdomen (tummy). It is usually seen as a bulge under the skin. An inguinal hernia is a hernia that occurs in the groin region. In boys, an inguinal hernia may extend into the scrotum. It affects one to five per cent of full-term babies. It is more common in boys and in premature babies (seven to 30 per cent). Boys are four to eight times more likely than girls to have an inguinal hernia.