BACKGROUND: Women with an obstetric anal sphincter injury are concerned about the risk of recurrent obstetric anal sphincter injury in their second pregnancy. Existing studies have failed to clarify whether recurrence of obstetric anal sphincter injury affects the risk of anal- and fecal incontinence at long term follow up.

OBJECTIVE: To evaluate whether recurrent obstetric anal sphincter injury influenced the risk of anal- and fecal incontinence more than 5 years after the second vaginal delivery.

STUDY DESIGN: We performed a secondary analysis of data from a postal questionnaire study in women with obstetric anal sphincter injury in the first delivery and one subsequent vaginal delivery. The questionnaire was sent to all Danish women who fulfilled inclusion criteria and had two vaginal deliveries 1997 -2005. We performed uni- and multivariable analyses to assess how recurrent obstetric anal sphincter injury affects the risk of anal incontinence.

RESULTS: In 1,490 women with a second vaginal delivery after a first delivery with obstetric anal sphincter injury, 106 had a recurrent obstetric anal sphincter injury. Of these, 50.0% (n=53) reported anal incontinence compared to 37.9% (n=525) of women without recurrent obstetric anal sphincter injury. Fecal incontinence was present in 23.6% (n=25) of women with recurrent obstetric anal sphincter injury and in 13.2% (n=182) of women without recurrent obstetric anal sphincter injury. After adjustment for third or fourth degree of obstetric anal sphincter injury in first delivery, maternal age at answering the questionnaire, birth weight of first and second child, years since first and second delivery and whether AI was present before second pregnancy, the risk of flatal and fecal incontinence was still increased in patients with recurrent obstetric anal sphincter injury, aOR 1.68 (95%CI 1.05-2.70) P = .03 and aOR 1.98 (95%CI 1.13-3.47) P =.02, respectively. More women with recurrent obstetric anal sphincter injury reported affected quality of life due to anal incontinence (34.9%, n=37) compared with women without recurrent obstetric anal sphincter injury (24.2%, n=335), although this difference did not reach statistical significance after adjustment, aOR 1.53 (95%CI 0.92-2.56) P =.10.

CONCLUSION: Women opting for vaginal delivery after obstetric anal sphincter injury should be informed about the risk of recurrence, which is associated with increased risk of long term flatal- and fecal incontinence.