How to evaluate a patient with known placenta previa (placenta (organ) that implants in the lower part of the uterus) who complains of vaginal bleeding?

From the Guidelines

A patient with known placenta previa who complains of vaginal spotting requires immediate evaluation in a hospital setting, as vaginal bleeding in placenta previa can rapidly progress to life-threatening hemorrhage. The patient should be instructed to go to the emergency department or labor and delivery unit for assessment. Initial evaluation should include:

• Vital sign monitoring
• Intravenous access with at least two large-bore catheters (18-gauge or larger)
• Blood typing and cross-matching for potential transfusion
• A complete blood count, coagulation studies, and fetal monitoring should be performed, as indicated by the American College of Radiology Appropriateness Criteria 1. Pelvic examination should be avoided as it may trigger significant bleeding, and instead, a gentle speculum examination may be performed by an experienced provider to rule out other causes of bleeding if necessary.

Ultrasound Assessment

Ultrasound assessment should be conducted to confirm placenta location and evaluate for any placental abruption, using transvaginal US, which is frequently necessary for evaluation of painful vaginal bleeding, especially if transabdominal US is inconclusive or inadequate 1. The evaluation should include visualization of the placenta, the inferior placental margin, the presence of any clot within the uterus, the continuity of the myometrium, the cervix from the external os to the internal os, and the identification of any vessels overlying the internal cervical os.

Management

Management depends on gestational age and bleeding severity - if bleeding is minimal and stops, the patient may be observed with continued monitoring; if bleeding is significant or persistent, delivery may be necessary regardless of gestational age. If less than 34 weeks gestation and the patient is stable, corticosteroids (betamethasone 12mg IM q24h for 2 doses or dexamethasone 6mg IM q12h for 4 doses) should be administered for fetal lung maturity, as recommended by the American College of Radiology Appropriateness Criteria 1. Tocolytics may be used for preterm contractions if there is no significant bleeding. This cautious approach is necessary because placenta previa involves abnormal placental implantation over the cervical os, which can lead to maternal hemorrhage and fetal compromise when disrupted.

From the Research

Evaluation of Patient with Placenta Previa and Vaginal Spitting

• The patient's condition should be assessed for associated conditions like placenta accreta and vasa previa, as these can impact management decisions 2
• A thorough evaluation should include a review of the patient's medical history, including prior cesarean delivery, advanced maternal age, and smoking, as these are key risk factors for placenta previa 2
• The patient's current symptoms, including the severity of vaginal spitting, should be carefully evaluated to determine the best course of management
• The use of antenatal corticosteroids may be considered to reduce neonatal morbidity and mortality, but the optimal timing of administration should be carefully considered, ideally within 1-7 days before birth 3

Management Options

• For patients with complete placenta previa, severe bleeding at presentation, uterine contractions, or a cervical length <25mm, delivery within 14 days is more likely, and management should be tailored accordingly 3
• Uterine artery embolization (UAE) may be an option for patients with placenta previa who desire vaginal delivery after intrauterine fetal death (IUFD) in a second-trimester pregnancy 4
• Guidelines recommend delivery at 36-37 6/7 weeks of gestation for stable women with placenta previa without bleeding or other obstetric complications 5
• In cases of active hemorrhage in the late preterm period, delivery should not be delayed for the purpose of administering antenatal corticosteroids 5

Monitoring and Follow-up

• Patients with placenta previa should be closely monitored for signs of bleeding or other complications, and management should be adjusted as needed 6
• The use of fetal lung maturity testing should not be used to guide management in the late preterm period when an indication for delivery is present 5
• Antenatal corticosteroids should be administered to women who are eligible and are managed expectantly if delivery is likely within 7 days, the gestational age is between 34 0/7 and 36 6/7 weeks of gestation, and antenatal corticosteroids have not previously been administered 5