Prior vertical uterine incision: Effect on subsequent pregnancy characteristics and outcomes

To examine characteristics and outcomes of cesarean delivery (CD) in women with a history of vertical hysterotomy.

This is a comparative study that retrospectively queried the National Inpatient Sample from October 2016 to December 2018. Pregnancy characteristics and surgical outcomes of CD among 18 575 women with prior vertical uterine incision were compared to 1 072 949 women with prior low-transverse incision, assessed by multivariable generalized estimating equation model and propensity score weighting.

In a multivariable analysis, women who had prior vertical uterine incision were more likely to have placenta percreta (odds ratio [OR] 3.41, 95% confidence interval [CI] 1.87-6.20), pre-labor uterine rupture (OR 2.70, 95% CI 1.52-4.80), in-labor uterine rupture (OR 2.33, 95% CI 1.55-3.51), and extreme preterm delivery <28 weeks (OR 17.8, 95% CI 15.2-20.7) in the current pregnancy, compared to those who had prior low-transverse uterine incision. In a weighted model, prior vertical hysterotomy was associated with increased surgical morbidity in current CD compared to prior low-transverse hysterotomy (10.6% vs. 4.8%, OR 2.02, 95% CI 1.81-2.26), including hemorrhage (OR 1.99, 95% CI 1.74-2.27) and hysterectomy (OR 3.67, 95% CI 2.97-4.53).

Prior vertical uterine incision at CD was associated with increased risk of placenta percreta, uterine rupture, particularly before labor, and adverse outcomes in the subsequent pregnancy.