How well do Cesarian or vaginal delivery of babies prevent anal incontinence?

Cesarean delivery (CD) is an ancient method of delivering a baby when there appears to be a risk to vaginal delivery; in most cases, a risk to the infant. However in modern times risk to the mother has also been considered in choosing this method of delivery, and increasingly the risk being considered is post partum pelvic floor dysfunction, which includes incontinence of flatus or faeces, together known as anal incontinence. In this systematic review of non-randomised studies, no benefit could be demonstrated for CD over vaginal delivery (VD) in the prevention of anal incontinence. This review encompasses 21 published studies, involving 31,698 women, delivered by 6,028 CD and by 25,170 VD. No randomised studies comparing CD to VD in average risk pregnancies exist. The above conclusion is therefore based upon less than optimal evidence.

Authors' conclusions: 

Without demonstrable benefit, preservation of anal continence should not be used as a criterion for choosing elective primary CD. The strength of this conclusion would be greatly strengthened if there were studies that randomised women with average risk pregnancies to CD versus VD.

Read the full abstract...

Caesarean delivery (CD) is a common form of delivery of a baby, rising in frequency. One reason for its performance is to preserve maternal pelvic floor function, part of which is anal continence.


To assess the ability of CD in comparison to vaginal delivery (VD) to preserve anal continence in a systematic review

Search strategy: 

Search terms include: "Caesarean section, Cesarean delivery, vaginal delivery, incontinence and randomised". PubMed, EMBASE and the Cochrane Central Register of Controlled Trials (Central) were searched from their inception through July, 2009.

Selection criteria: 

Both randomised and non-randomised studies that allowed comparisons of post partum anal continence (both fecal and flatus) in women who had had babies delivered by either CD or VD were included.

Data collection and analysis: 

Mode of delivery, and when possible mode of all previous deliveries prior to the index pregnancy were extracted, as well as assessment of continence post partum of both faeces and flatus. In Non-RCTs, available adjusted odds ratios were the primary end point sought. Incontinence of flatus is reported as a separate outcome.
Summary odds ratios are not presented as no study was analysed as a randomised controlled trial. Numbers needed to treat (NNT) are presented, that is, the number of CDs needed to be performed to prevent a single case of fecal or flatus incontinence, for each individual study. Quality criteria were developed, selecting studies that allowed maternal age adjustment, studies that allowed a sufficient time after the birth of the baby for continence assessment and studies in which mode of delivery of prior pregnancies was known. Subgroup analyses were done selecting studies meeting all quality criteria and in comparisons of elective versus emergency CD, elective CD versus VD and nulliparous women versus those delivered by VD or CD, in each case again, not calculating a summary risk statistic.

Main results: 

Twentyone reports have been found eligible for inclusion in the review, encompassing 31,698 women having had 6,028 CDs and 25,170 VDs as the index event prior to anal continence assessment . Only one report randomised women (with breech presentation) to CD or VD, but because of extensive crossing over, 52.1%, after randomisation, it was analysed along with the other 20 studies as treated, i.e. as a non-randomised trial. Only one of these reports demonstrated a significant benefit of CD in the preservation of anal continence, a report in which incontinence incidence was extremely high, 39% in CD and 48% in VD, questioning, relative to other reports, the timing and nature of continence assessment. The greater the quality of the report, the closer its Odds ratio approached 1.0. There was no difference in continence preservation in women have emergency versus elective CD.