Extra-abdominal hernias that occur in the groin area are collectively referred to as inguinal hernias. Common types include oblique inguinal hernias and direct inguinal hernias, of which oblique hernias are the most common, accounting for about 90% of all extra-abdominal hernias. The hernia sac protrudes through the outside of the inferior epigastric artery and the inguinal canal, passes through the inguinal canal obliquely inward, downward, and forward, and then passes through the inguinal canal and enters the scrotum. This is called an oblique inguinal hernia. It is more common in men, with a male-to-female ratio of about 15:1. The highest incidence rate is in infants, young children, and the elderly. Direct inguinal hernia refers to a hernia formed by the protrusion of abdominal visceral organs through the direct hernia triangle, which is more common in elderly men.