Ultrasound-guided selective block of the anterior branch of the obturator nerve for transurethral resection of bladder tumour

Abstract

Introduction: Bladder perforation is a serious complication of transurethral resection of bladder tumour (TURBT). One of the risk factors is an “obturator jerk”, caused by stimulation of the obturator nerve, causing powerful adduction of the leg. As almost half of all bladder tumours are located on the lateral wall and 55–100% of resections on the lateral wall can result in obturator jerk; this is not an insignificant risk. Patients: We have introduced regional anaesthetic nerve block of the anterior branch of the obturator nerve in patients with known lateral wall tumours undergoing TURBT. Methods: This procedure was performed by two consultant anaesthetists in our unit. Patients are positioned supine with the leg slightly abducted and laterally rotated. Ultrasound (US) is used to identify the anterior branch of the adductor longus, brevis and magnus muscles in the medial thigh, 2–3 cm inferior to the inguinal crease. The obturator nerve is situated in the plane between adductor longus and adductor brevis, medial to pectineus. An insulated needle is passed under US guidance and a nerve stimulator is used to elicit a twitch. Levobupivicaine is used to infiltrate the anterior branch of the obturator nerve to achieve motor block of the adductor brevis, adductor longus and gracillis muscles. TURBT is then performed. Results: This prospective pilot series includes 18 TURBT procedures. These were performed under spinal anaesthetic ( n=16) or general anaesthetic without muscle relaxant ( n=2). Tumours characteristics were; large flat areas of re-resection ( n=5), flat bladder lesions ( n=1) or exophytic lesions ( n=12). There were no incidences of obturator jerk observed during TURBT (0/18). There were no intra or post-operative complications. Conclusion: This simple technique can be easily applied to patients undergoing TURBT. Larger studies are required, but our series supports the use of this technique to reduce obturator jerk, which is an important risk factors for bladder perforation.