What are the delivery recommendations for patients with placenta previa?

Delivery Recommendations for Placenta Previa

For patients with placenta previa, planned cesarean delivery at 34-38 weeks of gestation is recommended, with the optimal timing being 34 0/7-35 6/7 weeks in stable patients to balance maternal and neonatal outcomes. 1, 2

Diagnosis and Classification

• Transvaginal ultrasound is the diagnostic modality of choice for accurate assessment of placenta previa 2
• Digital pelvic examinations should be avoided until placenta previa has been excluded to prevent triggering hemorrhage 2
• When the distance between the placental edge and internal cervical os is greater than 2 cm on ultrasound, women may safely have a vaginal delivery 3, 4
• When this distance is less than 2 cm but the placenta does not overlap the internal os, vaginal delivery may still be possible in select cases 4
• Cesarean delivery is mandatory when the placenta overlaps the internal cervical os (complete previa) 2, 3

Risk Assessment for Placenta Accreta Spectrum

• Women with placenta previa and prior cesarean deliveries should be evaluated for placenta accreta spectrum disorder 2
• The risk of placenta accreta increases 7-fold after one prior cesarean delivery and up to 56-fold after 3 cesarean deliveries 1
• Additional risk factors include advanced maternal age, high parity, prior uterine surgery, prior postpartum hemorrhage, and uterine anomalies 1
• MRI may be helpful in cases where ultrasound findings are concerning for placenta accreta 1

Timing of Delivery

• For uncomplicated placenta previa, delivery at 34 0/7-35 6/7 weeks is recommended 1
• Earlier delivery may be required for persistent bleeding, preeclampsia, labor, rupture of membranes, or fetal compromise 1
• Waiting beyond 36 0/7 weeks is not advised as approximately 50% of women with placenta accreta spectrum beyond 36 weeks require emergent delivery for hemorrhage 1
• Antenatal corticosteroids should be administered when delivery is anticipated before 37 0/7 weeks 1

Preoperative Planning

• Delivery should take place at an institution with adequate blood banking facilities and multidisciplinary expertise 2
• Preoperative coordination with anesthesiology, maternal-fetal medicine, neonatology, and expert pelvic surgeons is essential 1
• Notification and collaboration with the blood bank is recommended given the frequent need for large-volume blood transfusion 1
• Optimize hemoglobin values during pregnancy; treat anemia with oral or intravenous iron as needed 1

Intraoperative Management

• The uterine incision should be made away from the placenta when possible 2
• After delivery of the fetus, leave the placenta in situ if there is evidence of abnormal placental attachment 2
• Attempts at forced placental removal can result in profuse hemorrhage and should be avoided 2
• In cases of placenta accreta spectrum, cesarean hysterectomy may be necessary 2

Management of Complications

• When transfusing in the setting of acute hemorrhage, transfuse packed red blood cells, fresh frozen plasma, and platelets in a fixed ratio 2
• Baseline laboratory assessment at the initiation of bleeding should include platelet count, prothrombin time, partial thromboplastin time, and fibrinogen levels 2
• In cases of excessive blood loss (≥1,500 ml), re-dose prophylactic antibiotics 2

Special Considerations

• For asymptomatic placenta previa before 28 weeks, women can continue moderate physical activity 2
• After 28 weeks, women with placenta previa should avoid moderate-to-vigorous physical activity but can maintain activities of daily living 2
• Hospitalization is recommended for women with active bleeding 2
• For cases with suspected bladder involvement, consider ureteric stent placement and collaboration with urologic surgeons 2

Common Pitfalls and Caveats

• Failure to diagnose placenta accreta spectrum in women with placenta previa and prior cesarean deliveries can lead to catastrophic hemorrhage 1
• Digital examination in undiagnosed placenta previa can trigger severe hemorrhage 2
• Attempting vaginal delivery with complete placenta previa carries significant risks of maternal and fetal mortality 3
• Forced removal of an abnormally adherent placenta can result in life-threatening hemorrhage 2