What is the management for placenta previa?

Management of Placenta Previa

Diagnosis and Initial Assessment

Transvaginal ultrasound is the gold standard for diagnosing placenta previa, with 90.7% sensitivity and 96.9% specificity, and must be performed after initial transabdominal screening. 1, 2, 3

• Begin with transabdominal ultrasound, then proceed to transvaginal ultrasound for definitive assessment of placental location relative to the internal cervical os. 2, 3
• Measure the distance from the leading placental edge to the internal os—overlap of ≥15 mm at mid-trimester predicts persistence at delivery. 2, 3
• Never perform digital pelvic examination until placenta previa has been excluded, as this can trigger catastrophic hemorrhage. 1, 2, 3
• Use Doppler ultrasound to identify vasa previa and assess placental blood flow patterns, particularly for posterior placenta previa. 1, 3

Risk Stratification for Placenta Accreta Spectrum

All women with placenta previa and any prior cesarean delivery must be evaluated for placenta accreta spectrum disorder—the risk increases 7-fold after one cesarean and 56-fold after three cesarean deliveries. 1, 2, 3

• Additional risk factors include advanced maternal age, high parity, prior uterine surgery, prior postpartum hemorrhage, Asherman syndrome, uterine anomalies, smoking, hypertension, and in vitro fertilization. 1, 2, 3
• Consider MRI when ultrasound findings are concerning for placenta accreta, especially for posterior placenta previa or suspected placenta percreta. 1, 3
• Failure to diagnose placenta accreta spectrum in this population can lead to catastrophic hemorrhage—this is the most critical pitfall to avoid. 2, 3

Follow-Up Imaging Protocol

• Schedule ultrasound examinations at 18-20 weeks, 28-30 weeks, and 32-34 weeks to assess for previa resolution, placental location, and possible bladder invasion. 3
• If placenta previa persists at the 28-30 week ultrasound, immediately refer to a level III or IV maternal care facility with multidisciplinary expertise. 3

Antepartum Activity Management

• Women with asymptomatic placenta previa can continue moderate-to-vigorous physical activity before 28 weeks. 1, 2, 3
• After 28 weeks, prohibit moderate-to-vigorous physical activity but allow activities of daily living and low-intensity walking. 1, 2, 3
• Hospitalize immediately for any active bleeding. 1, 2, 3

Anemia Optimization

• Maximize hemoglobin values during pregnancy by treating anemia with oral or intravenous iron as needed to prepare for potential hemorrhage at delivery. 1, 3

Delivery Timing

Plan cesarean delivery at 34 0/7 to 35 6/7 weeks of gestation for uncomplicated placenta previa—this balances neonatal complications against increased maternal bleeding risk after 36 weeks. 1, 2, 3

• Administer antenatal corticosteroids when delivery is anticipated before 37 0/7 weeks. 1, 3
• Do not delay delivery beyond 36 0/7 weeks, as approximately 50% of women with placenta accreta spectrum beyond 36 weeks require emergent delivery for hemorrhage. 1, 2, 3
• Deliver earlier for persistent bleeding, preeclampsia, labor, rupture of membranes, or fetal compromise. 1, 2

Delivery Location and Team Assembly

Delivery must occur at a level III or IV maternal care facility with a multidisciplinary team including maternal-fetal medicine subspecialists, pelvic surgeons, urologists, interventional radiologists, obstetric anesthesiologists, and neonatologists. 1, 3

• Ensure the facility has a blood bank capable of employing massive transfusion protocols. 1, 3
• Notify the blood bank in advance due to the frequent need for large-volume blood transfusion. 1, 3
• Coordinate preoperatively with anesthesiology, maternal-fetal medicine, neonatology, and expert pelvic surgeons. 1, 3

Intraoperative Management

• Consider dorsal lithotomy positioning to allow vaginal access and optimal surgical visualization. 1
• Inspect the uterus after peritoneal entry to determine placental location and optimize the uterine incision approach. 1
• Make the uterine incision away from the placenta when possible. 1, 2
• For placenta accreta spectrum, leave the placenta in situ after fetal delivery—never attempt forced placental removal as this causes profuse hemorrhage. 1, 2
• For suspected bladder involvement, place ureteric stents and collaborate with urologic surgeons. 1, 3

Hemorrhage Management

Activate massive transfusion protocol early rather than late—delayed activation worsens outcomes. 2

• Transfuse packed red blood cells, fresh frozen plasma, and platelets in a 1:1:1 to 1:2:4 ratio for acute hemorrhage. 1, 3
• Obtain baseline laboratory assessment at bleeding initiation: platelet count, prothrombin time, partial thromboplastin time, and fibrinogen levels. 1, 3
• Keep patients warm (>36°C) during surgery as clotting factors function poorly at lower temperatures. 1, 3
• Re-dose prophylactic antibiotics if blood loss ≥1,500 ml. 1, 3
• Consider tranexamic acid to reduce blood loss. 2, 3
• For placenta accreta spectrum with uncontrollable bleeding, cesarean hysterectomy is necessary—this is the most accepted approach. 1, 2

Postoperative Care

• Provide intensive hemodynamic monitoring in the early postoperative period, ideally in an intensive care unit setting. 1, 2, 3
• Closely monitor volume status, urine output, blood loss, and hemodynamics. 1, 2, 3
• Maintain a low threshold for reoperation if ongoing bleeding is suspected. 2, 3
• Ensure adequate iron supplementation and follow-up of hemoglobin levels if significant blood loss occurred. 1, 3