From the Guidelines
Placenta previa is diagnosed in the third trimester when the placenta overlies the internal cervical os, posing significant risks to both maternal and fetal health through uncontrolled vaginal bleeding. This condition is common in the first half of pregnancy, but often resolves by 28 weeks, with 0.4% of all pregnancies diagnosed with placenta previa in the third trimester 1.
Key Characteristics of Placenta Previa
- Placenta previa is diagnosed after 28 weeks’ gestation when the placenta covers the internal cervical os
- The condition can cause uncontrolled vaginal bleeding, posing risks to both mother and fetus
- Not all women with placenta previa experience vaginal bleeding, but those who do not should still be re-evaluated for the presence of placenta previa at 28 weeks’ gestation 1
Management and Recommendations
- Women diagnosed with placenta previa after 28 weeks’ gestation should avoid moderate to vigorous physical activity (MVPA) to reduce the risk of spontaneous labor and bleeding
- However, these women should maintain their activities of daily living and low-intensity activity, such as walking 1
- The management of placenta previa depends on the severity, gestational age, and presence of bleeding, and often requires close monitoring and cesarean delivery
Clinical Implications
- Placenta previa is a significant pregnancy complication that requires careful management to prevent maternal and fetal morbidity and mortality
- Healthcare providers should be aware of the risks associated with placenta previa and provide guidance on activity levels and bleeding prevention to women diagnosed with the condition 1
From the Research
Definition of Placenta Previa
- Placenta previa is characterized by abnormal placental placement in the lower uterine segment, obstructing the cervical opening 2.
- It is defined as a condition where the placenta partially or completely covers the internal cervical os 3, 4.
- Placenta previa totalis occurs when the placenta completely covers the internal cervical os 2.
Key Characteristics
- Placenta previa can lead to placenta accreta spectrum (PAS), where the placenta adheres abnormally to the uterine wall, complicating separation 2, 5.
- The condition poses significant maternal risks, including hemorrhage and placenta accreta spectrum disorders 2, 5, 6.
- Perinatal outcomes are marked by increased rates of preterm birth, intrauterine growth restriction, and neonatal morbidity and mortality 6.
Diagnosis and Management
- Diagnosis is usually made by transabdominal ultrasonography 3.
- Management strategies include expectant management, avoidance of digital vaginal examination, delay of delivery until 36 weeks' gestation and/or documented fetal lung maturity, transfusion support, serial ultrasonography, antepartum fetal heart rate monitoring, glucocorticoids, tocolytic therapy, and elective delivery by cesarean section 3, 4.