What characterizes placenta previa?

Placenta previa is characterized by the placenta being implanted near or directly over the cervical opening. This condition can lead to complications during pregnancy and delivery, such as bleeding, especially as the cervix begins to dilate and efface in preparation for labor. The presence of the placenta over or adjacent to the cervical opening can impede a safe vaginal delivery and may necessitate a cesarean section.

The other options describe different conditions or situations that are not related to placenta previa. For instance, implantation away from the cervical opening denotes a normal placental position, while premature separation of the placenta refers to a different complication known as placental abruption. Cervical incompetence describes a situation where the cervix is unable to retain a pregnancy due to its structural weakness, which is not related to the positional dynamics of the placenta in relation to the cervix found in placenta previa.