Utility of Doppler velocimetry in predicting outcome in twin reversed-arterial perfusion sequence

OBJECTIVE: The aim of this study was to describe Doppler velocimetric findings in pregnancies complicated by the twin reversed-arterial perfusion sequence and to determine the association of these findings with pregnancy outcome. STUDY DESIGN: Six twin pregnancies complicated by twin reversed-arterial perfusion sequence had ultra-sonographic and Doppler studies performed between 1990 and 1997. Pulsatile vessels in the umbilical cords of the pump and acardiac twins were insonated, and reversal of flow was confirmed in all cases. Resistive index values were calculated, and the difference in resistive index between the pump and acardiac twin in each pair was evaluated as a marker of pregnancy outcome. RESULTS: Five of 6 pump twins survived the immediate neonatal period. Although 5 of the acardiac twins had abnormally elevated Doppler index values, no ratio of systolic to diastolic velocity or resistive index value of the acardiac twin alone was associated with either a good or poor prognosis for the pump twin. Among the 3 pump twins with good outcomes, all had a resistive index difference >0.20. Among the 3 pump twins with poor outcomes, all had small resistive index differences (<0.05). CONCLUSION: We found larger differences in resistive index to be associated with improved outcome of the pump twin in pregnancies complicated by twin reversed-arterial perfusion sequence. Smaller resistive index differences were associated with poor outcome, including cardiac failure and central nervous system hypoperfusion.