ABSTRACT
Our aim was to investigate the risk factors associated with severe perineal tears
defined as either third- or forth-degree tears and, ultimately, find strategies for
prevention. We carried a retrospective analysis of a computerized perinatal database,
collected prospectively, from a single county hospital between January 1, 1993 and
June 30, 1998. Singleton vaginal vertex deliveries were analyzed for potential risk
factors using univariate and multiple logistic regression analysis including all two-way
interactions. Severe perineal tear occurred in 1905 (8.2%) of 23,244 vaginal deliveries.
In the multiple logistic regression analysis, the following factors carried a significantly
higher risk for severe laceration: midline episiotomy, primary vaginal delivery, use
of pudendal block, forceps deliveries, and birth weight more than 4000 g. The study
of interactions demonstrated that mediolateral episiotomy was associated with an increased
risk for severe tear only during the first vaginal delivery, but not during a repeat
vaginal delivery. Our data suggest that primary vaginal delivery, fetal weight above
4000 g, and the use of pudendal analgesia can help identify in advance patients at
highest risk for severe perineal tear. During the delivery of these patients usage
of vacuum (instead of forceps) and restricting the use of midline episiotomy might
reduce the incidence of severe perineal tear. In cases where episiotomy seems crucial,
the use of a mediolateral episiotomy may reduce the likelihood of severe perineal
tear.
KEYWORDS
Third- and fourth-degree perineal lacerations - risk factors - regression and interaction
analysis
