What is the management plan for placenta previa?

Management of Placenta Previa

Women with placenta previa should undergo planned cesarean delivery at 34 0/7 to 35 6/7 weeks of gestation at a tertiary care center with multidisciplinary expertise and blood banking capabilities, with mandatory evaluation for placenta accreta spectrum in those with prior cesarean deliveries. 1, 2

Diagnostic Approach

• Transvaginal ultrasound is the gold standard for diagnosing placenta previa, with sensitivity of 90.7% and specificity of 96.9% 1, 2
• Perform transabdominal ultrasound initially as screening, followed by transvaginal ultrasound for definitive assessment 1, 2
• Never perform digital pelvic examination until placenta previa has been excluded, as this can trigger life-threatening hemorrhage 1, 2
• Measure the distance from the leading placental margin to the internal cervical os; overlap of ≥15 mm at mid-trimester predicts persistence at delivery 2
• Note that placenta previa is common in early pregnancy (42.3% at 11-14 weeks) but most resolve by 28 weeks 1

Critical Risk Stratification for Placenta Accreta Spectrum

This is the most important step that determines all subsequent management decisions:

• All women with placenta previa AND prior cesarean deliveries must be evaluated for placenta accreta spectrum disorder 1, 2
• Risk increases exponentially: 7-fold after one prior cesarean, up to 56-fold after three cesarean deliveries 1, 2
• 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
• Use ultrasound as primary screening; MRI may be helpful for posterior placenta previa or suspected placenta percreta 1
• Failure to diagnose placenta accreta spectrum can lead to catastrophic hemorrhage 2

Antepartum Activity Restrictions

• Before 28 weeks: Women with asymptomatic placenta previa can continue moderate-to-vigorous physical activity 1, 2
• After 28 weeks: Avoid moderate-to-vigorous physical activity but maintain activities of daily living and low-intensity activity such as walking 1, 2
• Hospitalize women with active bleeding 1, 2
• Consider outpatient management for selected stable patients after initial bleeding episode, which can reduce hospital days from 28.6 to 10.1 days with cost savings of $15,080 per patient 3

Preoperative Optimization

• Maximize hemoglobin values during pregnancy; treat anemia with oral or intravenous iron as needed 1, 2
• Coordinate preoperatively with anesthesiology, maternal-fetal medicine, neonatology, and expert pelvic surgeons (often gynecologic oncology or female pelvic medicine and reconstructive surgeons) 4, 1
• Notify blood bank in advance due to frequent need for large-volume blood transfusion 1, 2
• For suspected bladder involvement, consider ureteric stent placement and collaboration with urologic surgeons 1
• Establish baseline laboratory assessment including platelet count, prothrombin time, partial thromboplastin time, and fibrinogen levels 1

Timing of Delivery

The optimal delivery window is 34 0/7 to 35 6/7 weeks of gestation for uncomplicated placenta previa 4, 1, 2

• This timing balances neonatal complications against increased maternal bleeding risk after 36 weeks 4
• Do not wait beyond 36 0/7 weeks as approximately 50% of women with placenta accreta spectrum beyond 36 weeks require emergent delivery for hemorrhage 4, 1
• Administer antenatal corticosteroids when delivery is anticipated before 37 0/7 weeks 4, 1
• No amniocentesis is necessary at 34-35 weeks as pulmonary maturity data do not change clinical recommendations 4

Earlier delivery is required for:

• Persistent bleeding 4, 2
• Preeclampsia 4
• Labor or rupture of membranes 4
• Fetal compromise 4
• Developing maternal comorbidities 4

Delivery Location and Team Assembly

Delivery must occur at a level III or IV maternal care facility with the following capabilities: 4

• Multidisciplinary team including maternal-fetal medicine subspecialists, pelvic surgeons with advanced expertise (gynecologic oncologists or female pelvic medicine and reconstructive surgeons), urologists, interventional radiologists, obstetric anesthesiologists, critical care experts, general surgeons, trauma surgeons, and neonatologists 4
• Strong nursing leadership accustomed to managing high-level postpartum hemorrhage 4
• Blood bank capable of employing massive transfusion protocols 4
• Adequate surgical trays and necessary urologic equipment 4
• Cell-saver and intraoperative point-of-care testing capabilities 4

Intraoperative Management

Surgical approach:

• 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 uterine incision approach 1
• Make the uterine incision away from the placenta when possible 1, 2
• After delivery of the fetus, leave the placenta in situ if there is evidence of abnormal placental attachment 1
• Never attempt forced placental removal as this causes profuse hemorrhage 1, 2, 5

Hemorrhage management:

• Keep patients warm (>36°C) as clotting factors function poorly at lower temperatures 1
• When transfusing in acute hemorrhage, use a 1:1:1 to 1:2:4 ratio of packed red blood cells:fresh frozen plasma:platelets 1
• Re-dose prophylactic antibiotics if blood loss ≥1,500 ml 1
• Consider tranexamic acid to reduce blood loss 2
• Activate massive transfusion protocol early rather than late 2

For placenta accreta spectrum:

• The most accepted approach is cesarean hysterectomy with placenta left in situ 4, 1
• Attempts at placental removal are associated with significant hemorrhagic morbidity 6
• Regional anesthesia for cesarean delivery is safe 5

Postoperative Care

• Intensive hemodynamic monitoring in the early postoperative period, often best provided in an intensive care unit 1, 2
• Close monitoring of volume status, urine output, blood loss, and hemodynamics 1, 2
• Maintain a low threshold for reoperation if ongoing bleeding is suspected 1, 2
• Ensure adequate iron supplementation and follow-up of hemoglobin levels if significant blood loss occurred 1

Common Pitfalls to Avoid

• Performing digital examination without excluding placenta previa can trigger life-threatening bleeding 1, 2
• Failing to evaluate for placenta accreta spectrum in women with prior cesarean deliveries can lead to catastrophic hemorrhage 1, 2
• Delaying activation of massive transfusion protocol worsens outcomes 2
• Attempting placental removal when accreta is present causes profuse hemorrhage 1, 2, 5
• Delivering at facilities without adequate blood banking and multidisciplinary expertise increases morbidity 4, 5