Postpartum surveillance of urinary retention by ultrasonography: the effect of epidural analgesia.

Our objective was to investigate by ultrasonography whether the risk for postpartum urinary retention is increased following administration of epidural analgesia during labor and delivery. In a prospective study, 106 healthy women who had undergone vaginal delivery were evaluated. Sixty-eight of the women had received epidural analgesia during labor and delivery. All subjects had an ultrasound examination at a mean of 42 h after delivery, and residual urine volume was estimated immediately after voiding. Correlations among obstetric parameters, epidural analgesia and residual urine volumes were evaluated. The mean accuracy rate of ultrasonography for estimation of bladder volumes was +/- 10.2%. No cases of clinically evident urinary retention were diagnosed in the total puerperal population. There were no significant differences between the groups in the average amounts of residual urine as measured by ultrasonography. With modern obstetric practice, epidural analgesia for labor is not associated with an increased risk for postpartum urinary retention. The non-invasive nature of ultrasound renders it especially attractive and useful for measuring residual urine volume in postpartum patients. The safety, simplicity and relative comfort of this method over-ride the slightly imperfect calculations that it currently yields, and makes it preferable to catheterization or cystometry for evaluation of residual urine volume.