Risk factors for the recurrence of obstetrical anal sphincter injury and the role of a mediolateral episiotomy: an analysis of a national registry.

OBJECTIVE

The assessment of risk factors, including mediolateral episiotomy (MLE), for the recurrence of obstetric anal sphincter injury (rOASI).

DESIGN

Population-based cohort study.

SETTING

Data from the nationwide database of the Dutch Perinatal Registry (Perined).

POPULATION

A cohort of 391 026 women at term, of whom 9943 had an OASI in their first delivery and had a second vaginal delivery of a liveborn infant in cephalic position.

METHODS

Possible risk factors were tested for statistical significance using univariate and multivariate logistic regression analysis.

MAIN OUTCOME MEASURES

Rate of rOASI.

RESULTS

The rate of rOASI was 5.8%. Multivariate analysis identified a birthweight of ≥4000 g (adjusted OR, aOR, 2.1, 95% CI 1.6-2.6) and a duration of second stage of ≥30 minutes (aOR 1.8, 95% CI 1.4-2.3) as statistically significant risk factors for rOASI. Mediolateral episiotomy was associated with a statistically significant lower rate of rOASI in spontaneous vaginal delivery (SVD) (aOR 0.4, 95% CI 0.3-0.5) and in operative vaginal delivery (OVD) (aOR 0.2, 95% CI 0.1-0.5).

CONCLUSIONS

Women with a history of OASI have a higher rate of OASI in their next delivery. Duration of the second stage of ≥30 minutes and a birthweight of ≥4000 g are significantly associated with an increased rate of rOASI. Mediolateral episiotomy is associated with a significantly lower rate of rOASI in both SVD and OVD.

TWEETABLE ABSTRACT

Mediolateral episiotomy is associated with a significant lower recurrence rate of OASI in women with an OASI in their first delivery.