A 23 year old pregnant lady at 16 weeks pregnancy had vaginal spotting. She was found to have a uterus enlarged to 28 weeks' size and no fetal hea sound audible with the fetal Doppler. Human chorionic gonadotropin (hCG) serum levels are 1,00,000 miu/mL. Which of the following tests is most appropriate at this time?

A uterus dis-propoionately larger than the period of pregnancy is a strong possibility of hydatidiform mole. Serial hCG would be elevated well beyond normal levels. Ultrasound will show classic signs of molar tissue and is the test of choice. The Apt test is to detect fetal hemoglobin, of which there is none in complete molar pregnancies. Serial clotting function will not help in the immediate diagnosis