Life-threatening haemorrhage following obturator artery injury during transurethral bladder surgery: a sequel of an unsuccessful obturator nerve block

In spite of prior blockade of the obturator nerve with 1% mepivacaine (8 mi ) utilizing a nerve stimulator, violent leg jerking was evoked during trans urethral electroresection of a bladder tumour approximately 1 h after the b lockade in a 68-year-old man. The patient became severely hypotensive immed iately following the jerking, and a large lower abdominal swelling concurre ntly developed. The urgent laparotomy indicated that the left obturator art ery was severely injured by the resectoscope associated with the bladder pe rforation, causing acute massive haemorrhage. The patient recovered unevent fully after adequate surgery. Investigation of the literature suggested tha t both our nerve stimulation technique and anatomical approach were appropr iate. It was therefore unlikely that our block resulted in failure because of an inappropriate site for deposition of the anaesthetic. However, consen sus does not appear to have been obtained as to the concentration and volum e of the anaesthetic necessary for prevention of the obturator nerve stimul ation during the transurethral procedures. The concentration and volume of mepivacaine we used might have been too low and/or small, respectively, to profoundly block all the motor neuron fibres of the nerve. Alternatively, s timulation of the obturator nerve might occur because of the presence of so me anatomical variant, such as the accessory obturator nerve or its abnorma l branching. Ln conclusion, some uncertainty appears to exist in the effect iveness of the local anaesthetic blockade of the obturator nerve. In order to attain profound blockade of the motor neuron fibres of the obturator ner ve and thereby prevent the thigh-adductor muscle contraction which can lead to life-threatening situations, we recommend, even with a nerve stimulator , to use a larger volume of a higher concentration of local anaesthetic wit h a longer duration in the obturator nerve block for the transurethral proc edures.