Side incidence of inguinal hernias.

The reason for the right side predominance of inguinal hernias was studied. The case histories of 469 patients who had undergone inguinal hernia operations were analysed. 116 of the hernias were bilateral whereas 207 were right and 146 left sided, the difference being significant at the level p less than 0.05. More right than left hernias were found in every subgroup studied (children, women, men; direct, indirect, older people; with suspected increased intra-abdominal pressure). Neither of the two hypotheses envisaged for this side difference could be confirmed. These were a structural side difference in the inguinal canals, and a neuromusculature damaging abdominal incision. It is postulated that a physiological asymmetricity of the body musculature could be an explanation rather than any anatomical reason.