Objective: To evaluate trends in annual rates of vaginal birth, cesarean delivery, and obstetric anal sphincter injury at a single institution before and after the designation of obstetric anal sphincter injury as a measure of obstetric quality and safety.
Methods: This was a retrospective cohort study of women undergoing a singleton vaginal delivery and diagnosed with obstetric anal sphincter injury over a 16-year period. International Classification of Diseases, 9th Revision codes for perineal lacerations were used as identifiers. Trends in annual cesarean delivery, perineal laceration, and obstetric anal sphincter injury rates were assessed in a linear regression model. The data were divided into two time periods (1998-2005 and 2006-2013) based on the year (2006) in which obstetric anal sphincter injury was designated as a quality marker and compared.
Results: A total of 1,366 women had obstetric anal sphincter injury, and 1,360 were included for analysis. There was a 12.1% decline in annual vaginal delivery rates (from 77.1% to 67.8%) and a 40.6% increase in annual cesarean delivery rate (from 22.9% to 32.2%; P<.001). The rate of first-degree and second-degree laceration increased significantly (P=.009), and obstetric anal sphincter injury decreased significantly (P<.001). Operative vaginal birth and episiotomy were associated with obstetric anal sphincter injury in 2006-2013 compared with 1998-2005 (P<.001 and P=.018, respectively).
Conclusion: After the designation of obstetric anal sphincter injury as an institutional quality measure, rates of obstetric anal sphincter injury decreased.