Defining the position of deep inguinal ring in patients with indirect inguinal hernias

A preliminary survey of surgeons of all grades in our hospital revealed confusion about the position of the deep inguinal ring. Standard teaching is that the deep inguinal ring is lateral to the femoral artery. The aim of this study was to define the position of the deep ring in patients undergoing elective inguinal hernia repair. Thirty consecutive male patients undergoing indirect inguinal hernia repair under local anaesthesia were studied. The following landmarks were marked on the patient with a felt pen: anterior superior iliac spine (ASIS), femoral artery (FA), deep inguinal ring (DR), pubic tubercle (PT) and pubic symphysis (PS). The distance of each point from the ASIS was measured in centimetres. The relation of the femoral artery to the deep inguinal ring was confirmed by palpation through the deep ring during surgery. The femoral artery was consistently identified midway between the anterior superior iliac spine and pubic symphysis (mid-inguinal point). The deep inguinal ring was located medial (22/30) or above (8/30) the femoral artery, but never lateral. The mean distances from the anterior superior iliac spine to the deep ring and femoral artery were 8.8 and 7.7 cm, respectively. Contrary to standard teaching, this study demonstrates that the deep inguinal ring lies medial, not lateral, to the femoral artery. This may clarify some of the variations in textbook anatomy, and explain the difficulty in distinguishing direct and indirect inguinal hernias pre-operatively.