Effect of epidural analgesia on postpartum bladder sensation

Introduction: This study investigates the effects of epidural analgesia on postpartum urinary bladder sensation. Urinary retention and inability to void are well known side effects of epidural analgesia but the causes are unknown. The incidence of postpartum hypotonic bladder injury is increased in women receiving epidural analgesia during labour. We hypothesise that long-acting local anaesthetics used in epidural analgesia can impair bladder sensation and can lead to an increased risk of asymptomatic overdistension. Method: Primiparous women between 38-42 weeks gestation who had received epidural analgesia prior to being in labour were recruited. The women were catheterised prior to insertion of the epidural to obtain baseline bladder sensation measurements of first sensation to void and maximum bladder capacity from cystometry. Women who delivered by spontaneous vaginal delivery were followed up. Postnatally, cystometry was repeated until bladder sensation returned to within 10 % of the pre-delivery volumes, bladders were not filled beyond 600 ml. Results: Sixty women were recruited prior to insertion of the epidural but only eighteen were studied postpartum as they had a spontaneous vaginal delivery. The mean time for cystometry values to return to pre-delivery levels was 6.6 h with a maximum duration of 8 h. The mean volume of urine produced before bladder sensation returned was 1054 ml. Conclusion: Epidural analgesia delays the return of bladder sensation by up to 8-hours post-delivery. The volume of urine passed during this time can be as much as 1400 ml. Bladder catheterisation should be performed following epidural analgesia to minimise the possibility of bladder overdistension.