Technical advantages of ultrasound-guided obturator nerve block compared with the nerve stimulating technique

Background : We investigated the onset time of obturator nerve block and time required for the nerve block comparing two groups in a prospective randomized study. Methods : Obturator nerve block was performed in 37 cases by either nerve stimulation guide (NS group) or nerve stimulation and ultrasound guide (US group) with 10 ml of 1.5% lidocaine adding 1 : 200000 epinephrine. Results : There was no significant difference between the onset time in the NS group (6.1 min) and that in the US group (5.7 min). The time required for the nerve block (4.2 min vs 1.7 min) was significantly shorter, and the frequency of needle advancement for the optimal position (4.7 vs 1.7) was significantly smaller in the US group than in the NS group (P<0.05). Conclusions : Ultrasound imaging facilitated the identification of obturator nerves between adductor muscles. Ultrasound-guided obturator nerve block is a safe, quick and useful technique.