What characterizes a placental abruption?

A placental abruption is characterized by the separation of the placenta from the uterus before labor begins. This condition can occur at any point after the 20th week of pregnancy and is often associated with complications such as bleeding, abdominal pain, and fetal distress. The detachment may be partial or complete and can lead to significant risks for both the mother and the fetus, including preterm delivery and maternal hemorrhage.

The other options do not correctly define a placental abruption. Retention of the placenta post-delivery refers to a different complication where portions of the placenta remain in the uterus, which can lead to infection or excessive bleeding. Formation of a placenta previa involves the placenta being positioned low in the uterus and covering the cervix, which is distinct from an abruption, where the placenta detaches from the uterine wall. Finally, complete placenta previa specifically describes a condition where the placenta entirely covers the cervix, which is unrelated to the issue of placental detachment that characterizes an abruption. Thus, the correct identification of placental abruption as the separation of the placenta from the uterus before labor is crucial for appropriate management and intervention.