EVIDENCE on the long-term urinary consequences of obstetric anal sphincter injury (OASIS) remains limited. A longitudinal case–control follow-up study has now assessed urinary symptoms and their impact on quality of life 12 years after vaginal delivery, comparing women who sustained OASIS with matched controls and examining changes over time.
Researchers followed up a previously established cohort using a postal questionnaire incorporating two validated instruments: the Urogenital Distress Inventory (UDI-6), which measures the degree of bother caused by urinary symptoms, and the Incontinence Impact Questionnaire (IIQ-7), which evaluates the impact of urinary incontinence on quality of life. Questionnaires were sent to 242 women who had participated in earlier assessments, including 63 with a history of OASIS and 179 controls without sphincter injury. The response rate was high, at 76%.
Progression of Urinary Incontinence Over Time
At 12 years postpartum, no significant differences were observed between groups in terms of quality-of-life impact. Mean IIQ-7 scores were low and comparable for women with OASIS (1.1 ± 2.6) and controls (0.8 ± 1.7; p = 0.300), indicating a similar overall effect of urinary symptoms on daily life.
However, when changes over time were examined, urinary symptom severity increased significantly across the whole cohort. Mean UDI-6 scores rose from 2.5 at 6 years postpartum to 3.3 at 12 years (p < 0.001), suggesting a progressive increase in symptom bother with time following childbirth. This rise was more pronounced in women without OASIS, whose scores increased significantly from 2.3 to 3.2 (p < 0.001). In contrast, women with OASIS showed a smaller, non-significant increase in UDI-6 scores over the same period (3.0 to 3.5; p = 0.379).
Notably, these findings contrast with earlier results from the same cohort at 6 years postpartum, when women with OASIS reported more severe urinary symptoms than controls. By 12 years, this difference was no longer evident.
Implications for Long-Term Management of Urinary Incontinence
The authors conclude that while urinary incontinence symptoms tend to worsen over time following vaginal delivery, long-term severity and quality-of-life impact appear similar regardless of OASIS history. These findings highlight the importance of long-term follow-up for urinary symptoms after childbirth and suggest that factors beyond sphincter injury may contribute to progressive urinary dysfunction.
Reference
Rham Md et al. Urinary incontinence 12 years after obstetric anal sphincter injury in a longitudinal case control study. Sci Rep. 2026;doi:10.1038/s41598-026-36123-y.
