An ultrasound on a woman who is 32 weeks pregnant reveals the placenta implanted over the entire cervical os. What does the nurse understand describes this condition?

Choice A rationale Low-lying placenta describes a placenta implanted in the lower uterine segment where the edge is within 2 cm of the internal cervical os but does not cover it. This condition has a good chance of resolving (migrating upward) as the uterus enlarges. The description given—implanted over the entire cervical os—is a much more severe and complete form of the condition. Choice B rationale Total (or complete) placenta previa is the condition where the placenta completely covers the internal cervical os. This total coverage significantly prevents descent of the presenting part, often necessitates a Cesarean section, and is associated with the highest risk of antepartum hemorrhage (painless, bright red bleeding) due to the effacement and dilation of the cervix disrupting the placental attachment site. Choice C rationale Partial placenta previa occurs when the placenta covers only a portion of the internal cervical os when the cervix is fully dilated. This differs from the scenario given, where the placenta is described as implanted over the entire cervical os. While also a risk for bleeding, the portion of coverage is less than total. Choice D rationale Marginal placenta previa is a diagnosis where the edge of the placenta is immediately adjacent to the internal cervical os, but does not cover any portion of it. This is considered less severe than total or partial previa, having a better chance of vaginal delivery and less severe hemorrhage risk than the complete coverage described.