P176: Prenatal diagnosis of Arnold-Chiari III malformation by ultrasound and Fetal Magnetic Resonance Imaging (MRI)

or hyperemesis. Detailed Ultrasound examination with 4 MHZ transabdominal & 7 MHz endocavity transducers (Acuson-Aspen), revealed a normal fetus of 21 weeks with no congenital anomalies. But there was a large co existing intrauterine hypoechoic mass with multiple anechoic spaces, along the posterior wall. A small normal placenta was seen adjacent to the mass. A presumptive diagnosis of Hydatidiform mole co existing with a normal live fetus of 21 weeks was made on sonographic findings. After counseling, the parents decided to terminate the pregnancy, as the patient had a history of dilatation & evacuation for hydatidiform mole of at 12 weeks in the last pregnancy. A still-born fetus weighing 386 grams was delivered. Histopathological examination of the mass confirmed the diagnosis of complete hydatidiform mole. Discussion: The incidence of co-existence of normal live fetus with a complete hydatidiform mole is uncommon, (1%–2% of cases). This condition is usually the result of dizygotic twinning, thus fetus is chromosomally normal. However, the fetal survival until term is unlikely because of the maternal complications of the mole itself. Women who have had a previous molar gestation are at increased risk to develop a similar subsequent lesion.