Twin fetuses: Intravascular microbubble US contrast agent administration -Early experience

PURPOSE: To explore the feasibility of administering SH U 508A by using a s ingle-needle procedure at ultrasonography (US) in twin pregnancies to confi rm interfetal transfusion in monochorionic twins and delineate placental an gioarchitecture in pregnancies with twin-twin transfusion syndrome. MATERIALS AND METHODS: Fourteen twin pregnancies were studied over 12 month s: seven with monochorionic twins, including six with twin-twin transfusion syndrome; two of unknown chorionicity; and five with known dichorionic twi ns discordant for fetal karyotype or anomaly and undergoing selective fetic ide in the third trimester. Bolus injection of 100 mu L/kg of estimated fet oplacental weight of 400 mg/mL of SH U 508A was performed in the intrahepat ic vein of one twin, and evidence of interfetal transfusion was sought by m eans of digital analysis of power Doppler signals in the contralateral twin . RESULTS: Contralateral twin echo enhancement was seen in four of the nine u ltimately histopathologically proved monochorionic twins. As expected, no e vidence of echo enhancement in the contralateral twin was seen in any of th e five dichorionic twin pregnancies. There was no evidence of fetal comprom ise associated with the procedure. CONCLUSION: These pilot results suggest that microbubbles can be used to de monstrate interfetal transfusion but not to delineate placental vascular an atomy.