Comparison of proximal versus distal approach for ultrasound-guided obturator nerve block for prevention of adductor spasm in patients undergoing transurethral resection of urinary bladder tumors.

BACKGROUND AND AIMS: Adductor muscle spasm occurs when the obturator nerve is directly stimulated by the electrical current transmitted by the resectoscope. Ultrasound-guided ONB is regarded as the optimal technique and is classified as the proximal and distal approach based on the anatomical location of the obturator nerve.

MATERIAL AND

METHODS

This study included 90 adult patients of ASA grades I-III and aged more than 18 years undergoing transurethral resection of bladder tumors under spinal anesthesia. Patients were randomized into two groups: group P received ultrasound-guided obturator nerve block (ONB) by proximal approach, and group D received ultrasound-guided ONB by distal approach. Adductor muscle power after the block, block performance time, complications, and adductor jerks during surgery were compared. A P value of < 0.05 was considered statistically significant.

RESULTS

Adductor jerks during the surgery were absent in 85.7% of patients in group P and 78.0% of patients in group D. The mean block performance time in group P was 4.33 ± 0.38 minutes, and in group D was 4.00 ± 0.34 minutes. Vascular puncture during the block was observed in nine patients in group P and two patients in group D.

CONCLUSION

The success rate in terms of the absence of adductor spasm during surgery was higher in proximal than in distal ultrasound-guided ONB. However, the proximal technique requires more time to perform the block than the distal technique, as it is technically challenging and carries a risk of vascular puncture.