Anatomy of illoinguinal and illohypogastric nerves in relation to trocar placement and low transverse incisions

OBJECTIVE: The purpose of this study was to map the course of the ilioinguinal and iliohypogastric nerves. STUDY DESIGN: The courses of iliohypogastric and ilioinguinal nerves from 11 fresh frozen cadavers were mapped from their lateral emergence on the anterior abdominal wall to their midline termination in reference to fixed bony landmarks. Bivariate fit ellipses were generated for each nerve and compared with sites of standard abdominal surgical incisions. RESULTS: Thirteen iliohypogastric and 16 ilioinguinal nerves were identified and mapped. On average, the proximal end of the ilioinguinal nerve entered the abdominal wall 3.1 cm medial and 3.7 cm inferior to the anterior superior iliac spine, then followed a linear course to terminate 2.7 cm lateral to the midline and 1.7 cm superior to pubic symphysis. The iliohypogastric nerve entered the abdominal wall on average 2.1 cm medial and 0.9 cm inferior to the anterior superior iliac spine, which followed a linear course to terminate 3.7 cm lateral to the midline and 5.2 cm superior to pubic symphysis. CONCLUSION: Abdominal wall surgical sites below the level of the anterior superior iliac spine have the potential for ilioinguinal or iliohypogastric injury.