Consecutive cervical length measurements as a predictor of preterm cesarean section in complete placenta previa.

BACKGROUND

To evaluate whether consecutive cervical length measurements can predict preterm cesarean section in women with complete placenta previa.

METHODS

Seventy-one women with complete placenta previa were retrospectively categorized into women who delivered preterm due to massive hemorrhage (the preterm cesarean section group, n = 28) and those delivered at term (the control group, n = 43). Maternal characteristics, delivery outcomes, and cervical lengths serially measured at least every 2 weeks from 24 weeks' gestation until delivery were compared. The relationship between cervical length and preterm cesarean section was analyzed.

RESULTS

Cervical length gradually decreased with advancing gestational age. After 26 weeks' gestation, this decrease was significantly more rapid in the preterm cesarean section group. Cervical length before cesarean section in the preterm cesarean section group was significantly shorter than that in the control group. Just before cesarean section, 71.4% of the preterm cesarean section group presented with cervical lengths of ≤35 mm, whereas only 34.9% of the control group had cervical lengths of ≤35 mm (odds ratio 4.67, 95% confidence interval 1.66-13.10, p = 0.006).

CONCLUSIONS

In women with complete placenta previa, decrease in cervical length to ≤35 mm was associated with increased risk of preterm cesarean section due to massive hemorrhage.