Pain Following Obstetric Anal Sphincter Injuries: A Prospective Cohort Study.

Importance: Studies characterizing pain and pain management following obstetric anal sphincter injury (OASI) are limited.

Objectives: Our primary objective was to analyze time to pain resolution following OASI. Secondary objectives included analyzing pain severity, location, triggers, and patterns of pain medication use.

Study design: This was a prospective cohort study of patients with OASIs seen in a postpartum care clinic at a tertiary referral center between 2017 and 2022. We analyzed data on pain resolution, visual analog scale pain scores, pain triggers, pain location, and pain medications.

Results: A total of 362 patients were included in this study. In the Kaplan-Meier estimator, 58.5% of patients showed resolution of pain by 3 months following their initial postpartum care clinic visit, and 73.3% showed resolution of pain by 6 months. The median months to pain resolution was 2.2 (95% confidence interval: 1.6-3.0) for patients with third-degree lacerations and 2.3 (95% confidence interval: 1.6-6.8) for patients with fourth-degree lacerations. Visual analog scale scores showed the most improvement in the first 2 months. Common pain triggers included sitting and bowel movements in the first few months, as well as intercourse during later recovery. Pain location varied over time; bilateral pain in the levator ani muscles and obturator internus were most prevalent at each time point. Pain appeared to be predominantly managed by acetaminophen and ibuprofen.

Conclusions: Half of patients who experience OASI will have pain resolution by 2-3 months postpartum. Most patients will have resolution of their pain by 6 months postpartum.