Planned vaginal delivery versus planned cesarean delivery in cases of low-lying placenta

Objective: To assess the applicability of trial of labor in cases of low-lying placenta.Methods: In this observational cohort study, we collected data from the women with low-lying placenta delivered at our hospital between April 2012 and December 2015. Low-lying placenta was diagnosed when the length from the placental lowest edge to the internal cervical os (placenta-os distance) was 0-20mm at 36 gestational weeks. Planned mode of delivery for each case was determined by patient's preference. Maternal and neonatal outcomes were compared between the planned vaginal delivery group (N=11) and the planned cesarean delivery group (N=7).Results: All the women in the planned cesarean delivery group underwent scheduled cesarean section at 37-38 gestational weeks. Three cases in the planned vaginal delivery group required emergency cesarean section for uncontrollable antepartum bleeding. The intrapartum blood loss was significantly smaller in the planned vaginal delivery group than in the planned cesarean delivery group (946204g vs. 1649 +/- 256g, p=0.047). Umbilical arterial blood pH was similar between the two groups. All the women requiring emergency cesarean section were accompanied by marginal sinus.Conclusions: Trial of labor can be offered to all the women with low-lying placenta except for those accompanied by marginal sinus.