Cervical length predicts placental adherence and massive hemorrhage in placenta previa

To evaluate the relationship between cervical length (CL) and obstetrical outcome in women with placenta previa.

Eighty uncomplicated, singleton pregnancies with an antenatally diagnosed previa were categorized based on CL of over 30mm (n=60) or 30mm or less (n=20). A retrospective chart review was then performed for these cases to investigate the relationship between CL and maternal adverse outcomes.

The mean CL was 38.5±5.4mm and 26.9±3.2mm and the mean gestational age at measurement was 29.2±2.7 and 28.5±2.7weeks of gestation for the longer and shorter CL groups, respectively. The median estimated blood loss at cesarean section (CS) was significantly higher in the shorter CL group (1302mL vs 2139mL, P=0.023) as was the percentage of patients with massive intraoperative hemorrhage (60.0 vs 18.3%, P=0.001). In the shorter versus longer CL patients, emergent CS before 37weeks (23.3 vs 50.0%, P=0.046) and the percentage of patients with placental adherence (6.7 vs 35.0%, P=0.004) were both significantly more frequent in the shorter CL group. The shorter CL was a risk factor both for massive estimated blood loss (≥2000mL) (odds ratio 6.34, 95% confidence interval 1.91-21.02, P≤0.01) and placental adherence (odds ratio 6.26, 95% confidence interval 1.23-31.87, P≤0.05) in the multivariate analysis.

CL should be included in the assessment of a placenta previa given its relationship to emergent CS, cesarean hysterectomy, intraoperative blood loss and placental adherence.