Where exactly is the deep inguinal ring in patients with inguinal hernias?

It is difficult to distinguish direct from indirect inguinal hernias on clinical examination. This study attempted to determine an anatomical basis for this finding. Fifty adult patients with primary inguinal hernias were assessed. The position of the deep inguinal ring (DIR) was estimated from the position of the anterior superior iliac spine (ASIS) and the pubic tubercle (PT) pre-operatively and then the actual distance from these landmarks was measured intra-operatively. The DIR was actually located at a mean of 41% (95% confidence interval (CI) 26–56%) of the way along the inguinal ligament from the PT towards the ASIS (regression slope 1.203; 95% CI 1.141–1.127), compared with the 50% which would be expected from traditional clinical methodology. The DIR was actually found at a mean of 51% (95% CI 33–69%) of the way along a line from the pubic symphysis to the ASIS (regression slope 1.421; 95% CI 1.343–1.499). Pre-operative estimates of the position of the DIR are not accurate measures of its true position in patients with inguinal hernias. Clinical examination of inguinal hernias cannot rely on a constant position of the DIR to determine whether a hernia is direct or indirect.