(Poster 164) Impact of Urogynecology Evaluation on Subsequent Mode of Delivery After OASIS

Objectives: Previous studies have found that most patients who have births complicated by obstetric anal sphincter injuries (OASIS) will deliver vaginally in their subsequent birth. However, some elect to have a planned C-section (CS) due to risk of recurrent OASIS, or risk of new or worsening pelvic floor dysfunction. It is not well understood what factors influence mode of delivery for subsequent births after OASIS. We sought to evaluate the rates of planned CS in women with prior OASIS to identify if postpartum urogynecologic evaluation was associated with increased likelihood of scheduled CS.

Methods: This was a retrospective cohort study of all patients at a single institution who had OASIS in an index delivery between 2018-2023 and then had a subsequent birth within the same health system. Demographic and obstetric data was extracted from patient charts including attendance at a urogynecologist-led postpartum recovery clinic (PPRC) and evaluation with postpartum anorectal testing (PPART). PPART evaluation is offered to patients after attending PPRC and includes endoanal ultrasound and anorectal manometry. Primary outcomes were 1) rate of planned CS in patients who attended PPRC and those that did not, and 2) rate of planned CS in those who had PPART and those that did not. Secondary outcomes included rates of perineal lacerations for those that had a subsequent vaginal birth, including rate of recurrent OASIS. Descriptive statistics and logistic regression were used.

Results: Two hundred patients sustained OASIS in an index delivery and then had a subsequent delivery during the time period. There was a high overall attendance rate to PPRC (163/200, 81.5%) but fewer attended PPART (35/200, 17.5%). The overall rate of scheduled CS was 35.0% (70/200). Of those who had scheduled CS, the majority were for a history of prior OASIS (58/70, 82.9%). The scheduled CS rate was higher for those who attended PPRC compared to those that did not (40.5% vs 10.8 %, p=0.001), but no difference was seen between those who attended PPART and those who did not (p=0.92) (Table 1). On univariable analysis, PPRC attendance was associated with subsequent scheduled CS (OR 5.61, 95% CI 1.90-16.6). After controlling for race, insurance status, and operative delivery, PPRC attendees remained more likely to have a scheduled CS (aOR 4.36, 95% CI 1.35-14.01). Of patients who had subsequent vaginal deliveries, there were 7 recurrent OASIS (Table 2).

Conclusions: Patients who attended a urogynecologist-led postpartum clinic had higher rates of scheduled CS compared to those that did not attend. However, no difference was seen in scheduled CS rates among patients who had postpartum anorectal testing.