Bladder muscle biopsy and urethral sphincter EMG in patients with bladder dysfunction after pelvic surgery.

Eleven patients who suffered persistent bladder dysfunction after pelvic surgery have been investigated by needle urethral sphincter electromyography (EMG) and bladder muscle biopsy, and the results compared with those obtained in a series of controls. Individual motor units recorded from the urethral sphincter in patients who had undergone pelvic surgery were strikingly abnormal, suggesting the presence of reinnervation, and the density of detrusor innervation was significantly reduced. However, since reduction in the density of detrusor innervation may occur in circumstances other than peripheral nerve injury, we conclude that urethral sphincter EMG provides the most effective means of assessing damage to vesico-urethral innervation as a result of previous pelvic surgery.