What characterizes placenta increta?

Placenta increta is characterized by the abnormal penetration of the placenta into the myometrium, which is the muscular layer of the uterine wall. In this condition, the placental tissue invades not just the lining of the uterus (the endometrium) but makes its way deeper into the muscle of the uterus, which can lead to complications such as severe bleeding during delivery or the need for hysterectomy if the placenta cannot be separated from the uterine wall. This understanding of placental attachment is crucial for medical professionals as it impacts management and outcomes of pregnancies diagnosed with this condition.

The other options describe different conditions. The firm adherence of the placenta to the uterine wall is more characteristic of placenta accreta. Placement of the placenta over the cervix refers to placenta previa, which involves the location of the placenta rather than its depth of infiltration. Lastly, the complete absence of decidua would imply a condition where the decidual layer is missing, which is not a typical characteristic of increta. Thus, the correct identification of increta relates specifically to its invasive nature into the myometrium, distinguishing it from other placental abnormalities.