Retroperitoneal anatomy of the iliohypogastric, ilioinguinal, genitofemoral, and lateral femoral cutaneous nerve: consequences for prevention and treatment of chronic inguinodynia.

Purpose: Chronic inguinodynia is one of the most frequent complications after groin herniorrhaphy. We investigated the retroperitoneal anatomy of the iliohypogastric, ilioinguinal, genitofemoral, and lateral femoral cutaneous nerve to prevent direct nerve injury during hernia repairs and to find the most advantageous approach for posterior triple neurectomy.

Methods: We dissected the inguinal nerves in 30 human anatomic specimens bilaterally. The distances from each nerve and their entry points in the abdominal wall were measured in relation to the posterior superior iliac spine, anterior superior iliac spine, and the midpoint between the two iliac spines on the iliac crest. We evaluated our findings by creating high-resolution summation images.

Results: The courses of the iliohypogastric and ilioinguinal nerve are most consistent on the anterior surface of the quadratus lumborum muscle. The genitofemoral nerve always runs on the psoas muscle. The entry points of the nerves in the abdominal wall are located as follows: the iliohypogastric nerve is above the iliac crest and lateral from the anterior superior iliac spine, the ilioinguinal nerve is with great variability, either above or below the iliac crest and lateral from the anterior superior iliac spine, the genital branch is around the internal inguinal ring, the femoral branch is either cranial or caudal to the iliopubic tract, and the lateral femoral cutaneous nerve is either medial or lateral to the anterior superior iliac spine.

Conclusion: Nerve injury during inguinal hernia repairs can be avoided by taking the topographic anatomy of the inguinal nerves into consideration. The most advantageous plane to look for the iliohypogastric and ilioinguinal nerve during posterior neurectomy is on the anterior surface of the quadratus lumborum muscle. For the surgical treatment of severe chronic inguinodynia, especially after posterior open or endoscopic mesh repair (TAPP/TEP), the retroperitoneoscopic or open retroperitoneal approach for posterior triple neurectomy can be considered.