Comparison of inguinal versus classic approach for obturator nerve block in patients undergoing transurethral resection of bladder tumors under spinal anesthesia

Background: Selective obturator nerve blockade (ONB) is an effective option to prevent adductor spasm during transurethral resection of bladder tumors (TURBT) involving the lateral wall under spinal anesthesia (SA). The classic approach is less popular as the obturator nerve is deep seated and associated with vascular injury. The inguinal approach was described as a safer alternative. This randomized clinical study was undertaken to compare the ease of block, the success rate and complications of the classic pubic and superficial inguinal approach for ONB. Materials and Methods: A total of 30 patients scheduled to undergo TURBT under SA were administered bilateral ONB. Inguinal approach recently described by Choquet was performed on one side and classic approach described by Labat was performed on the other side in random order using a nerve stimulator. The ease of block, success rate (number of attempts to accomplish the block) and complications were noted and compared between both the approaches. Chi-square analysis was performed to compare the ease of approach of the two techniques. Non-parametric analyses using Mann Whitney test was used to compare the number of attempts to accomplish the block in each approach. A value of P < 0.05 was considered statistically significant. Results: The ease of block (P = 0.09) and the median number of attempts to accomplish the block (P = 0.45) were comparable between the two approaches. The incidence of vascular injury was higher in classic approach (P = 0.056). Conclusions: Inguinal approach is a useful alternative to classic approach block for patients undergoing TURBT under SA