Severe Perineal Trauma in a Brazilian Southeastern Tertiary Hospital: A Retrospective Cohort Study

This study aimed to investigate the prevalence of severe perineal trauma (obstetric and anal sphincter injury [OASIS]) in a tertiary high-risk pregnancy facility and the associated factors.

A retrospective electronic chart review on perineal lacerations was performed from the period of April 2017 to February 2019. Obstetric and anal sphincter injury was diagnosed by a rectal examination. Primary outcome was the prevalence of OASIS (third- and fourth-degree perineal tear). Independent variables were maternal, intrapartum, and neonatal characteristics. Univariate and multivariate analyses with logistic regression models were performed. A P value lower than 0.05 was considered significant.

The prevalence of OASIS (third/fourth-degree laceration) was 1.51% (43/2846) in our population. Our population was mostly white (66.3%) and mostly primiparous (52.1%). By comparison, the prevalence of first/second-degree laceration was 43% (1223/2846). Selective episiotomy occurred in 18.73% (517/2761) of patients, and it was not associated with OASIS (P = 0.211). Advanced maternal age (P = 0.196), higher number of vaginal examinations (P = 0.169), fetal presentation (P = 0.533), and duration of second stage (P = 0.757) were not associated with OASIS. Univariate analysis has found that forceps delivery (odds ratio [OR], 3.68 [1.74-7.79]; P = 0.001), neonatal macrossomy (OR, 3.42 [1.02-11.43]; P = 0.045), and larger head circumference (OR, 1.15 [1.02-1.32]; P = 0.026) were risk factors for OASIS, whereas higher gravidity reduced the risk (OR, 0.61 [0.42-0.91] for OASIS. However, after multivariate analysis, only head circumference (OR, 1.86 [1.10-3.14]; P = 0.020) remained as a risk factor.

Larger neonatal head circumference increased in 86% the risk for severe perineal trauma in this cohort of women.