In this abdominal pregnancy, the dead fetus was delivered through an abdominal incision at the 36th gestational week. The placenta invaded the small intestine and the omentum was left in situ. The placental degeneration was monitored using serial serum β-human chorionic gonadotropin values. In certain periods, the follow up of the placental regression was carried out using the Cavalieri method with abdominal ultrasound. It was seen that the placental volume had decreased by 83% at the end of 1 year. To the best of our knowledge, this is the first time this method has been used for this purpose.