Faecal Incontinence After Obstetric Anal Sphincter Injury: A Narrative Review of Sacral Neuromodulation and Why So Few Women Report the Symptom
DOI:
https://doi.org/10.5281/zenodo.22237015Keywords:
Obstetric Anal Sphincter Injury, Faecal Incontinence, Sacral Neuromodulation, Under-Reporting, Postnatal CareAbstract
Faecal incontinence after childbirth is common, treatable, and almost never mentioned. The literature contains two separate
failures of visibility: the injury that is not recognised in the delivery room, and the symptom the woman does not raise afterwards.
Both are quantified, and both are addressable.
Objectives: To review the published evidence on faecal incontinence following obstetric anal sphincter injury: how often the
injury occurs and is missed, how often symptoms follow and persist, why they are under-reported, and what sacral
neuromodulation and the alternatives achieve.
Material and Methods: Narrative review of systematic reviews, meta-analyses, national registry data, randomised trials of
neuromodulation and qualitative studies indexed in PubMed and the major obstetric, colorectal and urogynaecology journals. No
new patient data were generated; every estimate quoted is one published by the original investigators.
Results: Obstetric anal sphincter injury complicates approximately 3 to 6 per cent of vaginal births in primiparous women and
0.8 to 1.7 per cent in multiparous women, and more than half of injuries are not recognised in the delivery room. Among women
with an injury and one subsequent vaginal birth, long-term anal incontinence was reported in 41.0 per cent after a third-degree
tear and 58.8 per cent after a fourth-degree tear. Fewer than half of affected patients volunteer their symptoms. Secondary
sphincteroplasty achieves short-term continence in 60 to 80 per cent, with up to 40 per cent deteriorating over 5 to 10 years.
Conclusion: The dominant clinical problem is not that the treatments are poor but that the patients are not identified. Systematic
enquiry at postnatal review costs nothing and would find most of them, and the case for it does not depend on any of the contested
comparisons between surgical options.
Abbreviations: AI – Anal Incontinence, FI – Faecal Incontinence, FIQL – Faecal Incontinence Quality of Life scale, OASI –
Obstetric Anal Sphincter Injury, SMIS – St Mark's Incontinence Score, SNM – Sacral Neuromodulation.
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