From the Research
The three types of placenta previa are low-lying placenta, "marpartial" (marginal and partial) placenta previa, and complete placenta previa, as recently proposed in a 10-year retrospective cohort study 1. These classifications are important because they help determine management and delivery planning.
- Low-lying placenta refers to when the placenta implants in the lower uterine segment but does not reach the cervix.
- "Marpartial" placenta previa includes both marginal and partial placenta previa, where the placental edge is within 2 cm of the internal cervical os or partially covers the os.
- Complete placenta previa occurs when the placenta completely covers the internal cervical os. Complete previa carries the highest risk of bleeding and almost always requires cesarean delivery, while low-lying placenta may sometimes allow for vaginal delivery if the placental edge moves away from the os as the pregnancy progresses. The primary concern with all types of placenta previa is the risk of painless vaginal bleeding, which can be life-threatening for both mother and baby, particularly in the third trimester when the lower uterine segment begins to thin and stretch in preparation for labor, as discussed in various studies 2, 3, 4, 5.