Cervical length predicts placental adherence and massive hemorrhage in placenta previa

Journal of Obstetrics and Gynaecology Research, 10/20/2011

Fukushima K et al. – Cervical length (CL) should be included in the assessment of a placenta previa given its relationship to emergent cesarean section (CS), cesarean hysterectomy, intraoperative blood loss and placental adherence.


  • Eighty uncomplicated, singleton pregnancies with an antenatally diagnosed previa were categorized based on CL of over 30 mm (n = 60) or 30 mm 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 ± 5.4 mm and 26.9 ± 3.2 mm and the mean gestational age at measurement was 29.2 ± 2.7 and 28.5 ± 2.7 weeks 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 (1302 mL vs 2139 mL, 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 37 weeks (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 (>=2000 mL) (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.

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