[Obturator nerve block]

Obturator nerve block is commonly used for transurethral resections of the bladder in order to inhibit reflectory adductor muscle reaction during electrocoagulation and to reduce the risk of bladder wall perforation during transurethral surgery. Furthermore, obturator block is used to complete regional blocks for major knee surgery in addition to femoral and sciatic nerve blocks. Continuous techniques are sometimes used to treat chronic pain problems such as adductor spasm. During a so called "3 in 1" block (femoral nerve block) the obturator nerve will only be anaesthetized in 0-62% of the patients. Therefore, a specific approach to the obturator nerve is deemed appropriate. In addition, an accessory branch of the obturator nerve will accompany the femoral nerve in 10-30% of the patients. The classical approach uses the tuberculum pubicum as an anatomical landmark, inserting the needle approximately 1.5cm lateral and caudal until bone contact is established. After laterocaudal redirection the canalis obturatorius is reached and the local anaesthetic is injected. The alternative approach is more often used: At the proximal tendon insertion of the adductor longus muscle the needle is introduced and advanced towards the anterior superior iliac spine. For both approaches a nerve stimulator is used and 15-20ml of local anaesthetic solution are injected.