Predictors of third- and fourth-degree lacerations in forceps-assisted delivery: a case-control study.

INTRODUCTION: The objective of this study was to develop a model for predicting perineal lacerations in women attempting forceps-assisted delivery.

METHODS: We identified all forceps-assisted deliveries at our institution from January 1, 2002 to June 30, 2012. Multiple gestations were excluded. The laceration group included third and fourth degree was compared with a control group including a random sample of women who had a forceps-assisted delivery without lacerations. Regression models were used to develop the best model for predicting perineal lacerations associated with forceps-assisted delivery.

RESULTS: Out of a total of 17,111 vaginal deliveries, 794 (4.6%) had a forceps-assisted delivery. After exclusions, 769 women were included. Of those, 146 (19.0%) had lacerations. The laceration group was significantly older, had more primiparas, more pregnancy greater than 40 weeks of gestation, more forceps-assisted delivery for arrest, longer second stage, more occipitoposterior position, and less use of episiotomy (). The following were independent predictors in the final model: age younger than 30 years, pregnancy greater than 40 weeks of gestation, primiparous, occipitoposterior position, and absence of episiotomy with adjusted odds ratio of 2.4 (95% confidence interval [CI] 1.4-4.2), 1.9 (95% CI 1.2-3.1), 3.6 (95% CI 1.9-7.3), 2.0 (95% CI 1.0-3.9), and 2.2 (95% CI 1.3-3.7), respectively. The final model had a range of predicted probabilities (11-90%) ().(Table is included in full-text article.)(Figure is included in full-text article.)

CONCLUSION: : We present a model that can accurately stratify patient risk for laceration during forceps-assisted delivery.