The long-term effects of obstetrical anal sphincter injury on pelvic floor function

Link directly to the doctoral thesis in GUPEA

Pressrelease ,February 23, 2023

Read a short summary in AkademiLiv: Higher risk of future accidental bowel leakage after sphincter injury

The thesis examines the long-term effects on pelvic floor function after childbirth with one or two anal sphincter injuries and with or without vacuum extractor. Close to 2 million women in four countries are included in the research

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As women live longer, the long-term effects of childbirth may negatively affect their quality of life and professional careers.

This thesis investigates the long-term effects of vacuum extraction and of one and two obstetrical anal sphincter injuries (OASIs) on pelvic floor function. Also, temporal trends of OASI incidence were compared in four countries with comparable national medical birth registers and healthcare systems.

Women with one or two deliveries were studied, and national birth register data were used and were in three studies linked to information from questionnaire surveys on current pelvic floor disorders.

OASI occurred three times more often during a vacuum compared to a spontaneous delivery, and the risk for a repeat OASI almost tripled after the first OASI. The long-term prevalence of faecal incontinence doubled and tripled, and there was a significant trend of more frequent leakage and an increasing impact of anal incontinence after one and two OASIs, compared to no OASI. The incidence of OASI in women with one vaginal delivery varied widely over time and between Austria, Canada, Norway, and Sweden, and only Norway reported a consistent and significant decrease.

In summary, OASI was a potent risk factor for the prevalence, severity, and impact of long-term anal and faecal incontinence. Perineal protection, when systematically and persistently applied, may lower the rate of OASI.

Figure 1 :“Components of anal and fecal incontinence in women with no, one, or two obstetrical anal sphincter injuries”CI, confidence interval; OASI, obstetrical anal sphincter injury.
Reproduced from Nilsson et al. Symptoms of fecal incontinence two decades after no, one, or two obstetrical anal sphincter injuries. Am J Obstet Gynecol 2021 Mar;224:276.e1-.e23 (and page 42 in thesis)