A transvaginal ultrasound scan (TVUS) was performed using a GE Healthcare (Milwaukee, WI, USA) scanner, equipped with a 5-9 MHz endo-cavity transducer. Realtime grey scale examination revealed an anteverted uterus, which was slightly bulky but had no obvious focal lesion. The endometrium was echogenic with an endometrial thickness measuring 12.4 mm. No gestational sac was seen within the endometrial cavity. The right ovary appeared normal in size and echo patty. It measured 2.7×0.8×1.9 cm. (volume 4.1 cc). The left ovary appeared normal; however,in the left adnexa, adjacent to the ovary,athick-walled cystic mass measuring 2.0×2.5 cm was identified.On further exploration, there was evidence of two yolk sacs and two embryonic poles (Frgure1), both demonstrating cardiac activity seen within a single gestation sac. No inter-twin membrane separating the two embryos ultrasound (Figure3) confirmed the presence of cardiac activity in both embryonic poles.