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Placenta previa

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Last update: 
September 23, 2009
Authors: 
Vincenzo Berghella

Key Points

Distance from placental edge to internal os (i.o.) of the cervix: - >20mm: recommend vaginal delivery (cesarean delivery (CD) not indicated) - 11-20mm: vaginal delivery can be attempted; risk of hemorrhage 3% antepartum, and 10% intra/postpartum. Median blood loss at delivery 500cc. - 0-10mm: suggest CD -- Overlap: recommend CD

Pregnancy Management

Delivery

MODE:
Distance from placental edge to internal os (i.o.) of the cervix: - >20mm: recommend vaginal delivery (cesarean delivery (CD) not indicated) - 11-20mm: vaginal delivery can be attempted; risk of hemorrhage 3% antepartum, and 10% intra/postpartum. Median blood loss at delivery 500cc. Chance of cesarean delivery about 31%. - 0-10mm: suggest CD (hemorrhage antepartum 29%, and 21% intra/postpartum. Median blood loss at delivery 662cc. Chance of cesarean delivery 75%). - Overlap: recommend CD.1

TIMING:
For women with placenta previa (overlap or within 10mm from internal os), consider delivery at 37 weeks after mature FLM by amniocentesis, or at 38 weeks (without need for amniocentesis).

 

  1. 1. Vergani P, Ornaghi S, Pozzi I, et al. placenta previa: distance to internal os and mode of delivery. Am J Obstet Gynecol 2009;201:266.e1-5.

Historic notes

Terms such as partial, marginal, placenta previa were based on palpation of the placenta through the cervix in an era before transvaginal ultrasound. These terms should be avoided in current practice. 1

  1. 1. Oppenheimer LW, farine D. A new classification of placenta previa: Measuring progress in obstetrics. Am J Obstet Gynecol 2009;201:227-9.