Comparison of efficacy of transversus abdominis plane block and iliohypogastric/ilioinguinal nerve block for postoperative pain management in patients undergoing inguinal herniorrhaphy with spinal anesthesia: a prospective randomized controlled open-label study.

Purposes: The purpose of this study was to compare the effects of lateral abdominal transversus abdominis plane block (TAP block) and iliohypogastric/ilioinguinal nerve block (IHINB) under ultrasound guidance for postoperative pain management of inguinal hernia repair. Secondary purposes were to compare the complication rates of the two techniques and to examine the effects of TAP block and IHINB on chronic postoperative pain.

Methods: This was a prospective randomized controlled open-label study. After approval of the Research Ethics Board, a total of 90 patients were allocated to three groups of 30 by simple randomized sampling as determined with a priori power analysis. Peripheral nerve blocks (TAP block or IHINB) were administered to patients following subarachnoid block according to their allocated group. Patient pain scores, additional analgesic requirements and complication rates were recorded periodically and compared.

Results: Pain scores were significantly lower in the study groups (p < 0.001, p < 0.001, p < 0.001, p = 0.002, p < 0.001, p < 0.001 for 1, 2, 4, 6, 24, and 48 h and at 1 and 6 months, respectively). First pain declaration times were significantly longer in the study groups (TAP block group [GT] 266.6 ± 119.7 min; IHINB group [GI] 247.2 ± 128.7 min; and control group [GC] 79.1 ± 66.2 min; p < 0.001). At 24 h, the numeric rating scale scores of GT were significantly lower than GI (p = 0.048). Additional analgesic requirements of GT and GI patients were found to be significantly lower than GC patients (p = 0.001, p < 0.001, p = 0.006, p = 0.002, p = 0.001, p < 0.001 for 1, 2, 4, 6, 24, and 48 h, respectively).

Conclusion: We conclude that administration of TAP block or IHINB for patients undergoing inguinal herniorrhaphy reduces the intensity of both acute and chronic postoperative pain and additional analgesic requirements.