When part of an internal organ protrudes through an abnormal opening in the containing wall of its cavity, a hernia results. In an inguinal hernia—the most common type—the large or small intestine, omentum, or bladder protrudes into the inguinal canal.

Inguinal hernias can be classified as reducible (if the hernia can be manipulated back into place with relative ease), incarcerated (if the hernia can’t be reduced because adhesions have formed in the hernial sac), or strangulated (if part of the herniated intestine becomes twisted or edematous, causing serious complications).

Inguinal hernias can be direct or indirect, depending on where the abnormal opening in the inguinal canal occurs. When indirect, the hernia causes the abdominal viscera to protrude through the inguinal ring and follow the spermatic cord (in males) or round ligament (in females). When direct, it results from a weakness in the fascial floor of the inguinal canal.