Prediction of Delivery Complications by First-Trimester Ultrasound Measurement of the Gestational Sac's Distance From a Previous Cesarean Section Scar.

OBJECTIVES

This study was designed to investigate the clinical relationship between labor complications in the second and third trimesters and the distance from the gestational sac to a previous cesarean section (CS) scar.

METHODS

We conducted a retrospective review of the electronic medical records and included all 7- to 9-week transvaginal ultrasound examination reports from pregnancies with a history of a single cesarean delivery in our hospital between January 2015 and December 2017. Women were divided into 6 groups according to the distance of the gestational sac to the CS scar (groups A-F). A composite of pregnancy outcomes (gestational age at birth, delivery mode, placental abnormality, blood loss, uterine rupture, and hysterectomy) and other maternal and neonatal outcomes were assessed.

RESULTS

A total of 699 cases were included in our study. The median gestational age was 39.0 (range, 38.1-39.9) weeks. The median intrapartum blood loss volume was 400 (range, 300-500) mL. The results showed no statistically significant difference in blood loss (P = .297) or birth weight of the neonate (P = .318) among the distance subgroups. Overall, the fetuses were stillborn in 9 of 699 cases (1.29%). There was a statistically significant difference in a morbidly adherent placenta, placenta previa, and preterm labor, and their incidence increased with decreasing distance (P < .001; P for trend < .05). There was no statistically significant difference in uterine rupture (P = .597) or the delivery mode (P = .187) among the subgroups.

CONCLUSIONS

The relative positions of a CS scar and the gestational sac in the first trimester are associated with the incidence of placental abnormalities. As the distance decreases, the extent of a morbidly adherent placenta increases.