920: The relationship between perinea length and obstetric anal sphincter injuries

Abstract

To evaluate the association between perineal length and obstetric anal sphincter injuries (OASIS). This is a secondary analysis of a randomized prospective trial that examined the outcomes of standard care vs avoiding episiotomy in women towards their first vaginal delivery. In the current analysis, we included only women whose perineal length was documented. Women with a perineal length of 2 mm or less were compared to the remaining cohort. Our primary outcome was the rate of OASIS. Secondary outcomes included demographic and obstetrical information (including maternal age, body mass index, gestational age, neonatal weight, vacuum delivery, and episiotomy). Overall, 399 women who achieved vaginal delivery were included in the analysis. Of these, in 26 cases the perineum was below 2 cm (6.5%). These women had a significantly higher incidence of OASIS compared to women with a perineal length of “≥ 2 cm” (11% versus 2.5%, respectively, p= 0.0365). Secondary outcomes did not differ between groups (Table 1). Perineal length of 2 cm or less was associated with higher rates of OASIS. This should guide practitioners to protect the perineum with extra care in such cases.