From the Research
Introduction to Placenta Previa
Placenta previa is a condition where the placenta partially or completely covers the internal cervical os, posing significant risks to both the mother and the fetus [ 1 ]. This condition is characterized by abnormal placental placement in the lower uterine segment, obstructing the cervical opening [ 2 ].
Signs and Symptoms
The primary symptom of placenta previa is painless vaginal bleeding, which can occur in the second or third trimester of pregnancy [ 2 ]. Other symptoms may include uterine contractions and premature labor. It is essential to note that placenta previa can lead to placenta accreta spectrum (PAS), where the placenta adheres abnormally to the uterine wall, complicating separation [ 2 ].
Risk Factors
Key risk factors for placenta previa include prior cesarean delivery, advanced maternal age, and smoking [ 1 ]. Additionally, women with a history of multiple cesarean sections are at increased risk of developing placenta accreta spectrum [ 2 ].
Diagnosis
Diagnosis of placenta previa is typically made during routine second-trimester ultrasound [ 1 ]. Transabdominal ultrasonography is commonly used to diagnose placenta previa, although false-positive diagnoses can occur in the second trimester [ 3 ].
Treatment Options
Treatment for placenta previa usually involves expectant management, including:
- Avoidance of digital vaginal examination
- Delay of delivery until 36 weeks' gestation and/or documented fetal lung maturity
- Transfusion support to maintain maternal hematocrit greater than or equal to 30%
- Serial ultrasonography
- Antepartum fetal heart rate monitoring
- Glucocorticoids
- Tocolytic therapy
- Elective delivery by cesarean section [ 3 ]
In cases where placenta previa persists into the late third trimester, a planned cesarean delivery is recommended [ 1 ]. For women with placenta accreta spectrum, management strategies may include feeder vessel ligation and conservative approaches to minimize hemorrhage [ 2 ]. In cases of uncontrollable bleeding, hysterectomy may be necessary [ 2 ].
Differential Diagnosis and Caveats
It is essential to assess for associated conditions like placenta accreta and vasa previa when diagnosing placenta previa [ 1 ]. Additionally, optimization of diagnosis and management protocols can help improve maternal, fetal, and postnatal outcomes [ 4 ]. Effective communication, timely decision-making, and adherence to massive hemorrhage protocols are critical in managing obstetric emergencies like placenta accreta spectrum [ 2 ].