Many structures pass into and out of the abdominal cavity creating weakness which can lead to hernia formation. The most common example is the inguinal canal in males, along which the testis descends from abdomen to scrotum at the time of birth. The testicular artery, veins and vas pass though this canal (the round ligament in females). The resultant weakness leads to an indirect or lateral-type inguinal hernia. In adult surgery, 80% of all hernia repairs are for inguinal her- nia. The evolutionary advantage of testicular descent must outweigh the disadvantage of a high risk of herniation.