Is the extent of obstetric anal sphincter injury correlated with the severity of fecal incontinence in the long term?

Background: Obstetric anal sphincter injury is the most frequent cause of fecal incontinence (FI) in young women. However, the relationship between the extent of anal sphincter defects and the severity of long-term FI (at least 1 year after delivery) has been poorly studied. The aim of the present study was to determine if, in the long term, the extent of anal sphincter defects graded at anal endosonography was linked with the severity of FI.

Methods: A retrospective study was conducted on women with a history of vaginal delivery, who presented with FI and had three-dimensional anorectal high-resolution manometry and endoanal ultrasound in our center from January 2015 to 2016. The detailed clinical history of each patient was obtained from the institutional database. The severity of FI was assessed with the Jorge and Wexner continence scale.

Results: There were 250 women with a mean age of 60 ± 14 years. Seventy-six (30.4%) had an isolated defect of the internal anal sphincter, 21 (8.4%) had an isolated defect of the external anal sphincter, and 150 (60%) had both internal and external sphincter defects. The extent of IAS and EAS defects was proportionally correlated with the decrease in mean resting anal pressure (p < 0.01) and the decrease in mean squeeze pressure (p = 0.013) measured by 3DHRAM. No significant correlation was found between the extent and location of the defect (IAS, EAS or both) on endoanal ultrasound and the severity of FI. Menopause was the only independent factor significantly associated with the severity of FI.

Conclusions: In our study, no significant correlation was observed between the extent of the anal sphincter defect and the severity of FI. Menopause was the only identified and independent risk factor for FI. These data confirm that, in the long-term, FI is often multifactorial.