Randomised clinical trial of a laxative alone versus a laxative and a bulking agent after primary repair of obstetric anal sphincter injury

Objective To compare two postpartum laxative regimens in women who have undergone primary repair of obstetric anal sphincter injury. Design Randomised controlled trial. Setting National Maternity Hospital, Dublin. Population A total of 147 postpartum women who had sustained anal sphincter injury at vaginal birth. Methods Women were randomised to receive either lactulose alone thrice daily for the first three postpartum days followed by sufficient lactulose to maintain a soft stool over the following 10 days (lactulose group, n = 77) or the lactulose regimen combined with a sachet of ispaghula husk daily for the first 10 postpartum days (Fybogel (TM) group, n 70). All patients kept a diary of bowel habit for the first 10 postpartum days and were invited to return for review at 3 months postpartum. Main outcome measures Patient discomfort with first postpartum bowel motion, incidence of postnatal constipation and incontinence and incontinence score in postnatal period. Results Pain scores were similar in the two treatment groups; but incontinence in the immediate postnatal period was more frequent with the two preparations compared with lactulose alone (32.86% versus 18.18%, P = 0.03). Conclusions This study does not support routine prescribing of a stool-bulking agent in addition to a laxative in the immediate postnatal period for women who have sustained anal sphincter injury at vaginal delivery.