Prognostic markers in twin pregnancies with an acardiac fetus

Objective: With twin reversed arterial perfusion sequence, the normal cotwi n is at risk of heart failure. The purpose of this study was to identify ul trasonographic variables that can help predict prognosis. We hypothesized t hat variables reflecting the hyperdynamic circulatory condition of the norm al fetus and the changes in circulatory impedance in the acardiac mass woul d correlate with final outcome. Methods: Ten twin pregnancies with this condition were identified. Follow-u p was available for nine. Adverse outcome was defined as death, cardiac fai lure, or delivery before 30 weeks' gestation for reasons related to the pre sence of the mass. The following data were collected on the normal fetus: c ardiothoracic ratio and left ventricular shortening fraction; and on the ma ss: maximal length, presence and size of cysts, and presence of a rudimenta ry heart. The pulsatility index (PI) of the umbilical arteries (UA) of both twins was measured. Results: Four fetuses died, two in utero (22 weeks) and two after cesarean (26 and 31 weeks) for advanced cardiac failure. In the five other cases, th e outcome was favorable. The cardiothoracic ratio and presence of cysts or of a rudimentary heart did not correlate with outcome. A PI in the mass' UA significantly lower than that of the normal twin (ratio of 0.71 compared w ith 1.04 for good outcome, P < .05), an elevated shortening fraction in the second trimester, and a rapid growth rate of the mass were associated with a poor prognosis. Conclusion: In pregnancies with twin reversed arterial perfusion sequence, final outcome and treatment decisions can be determined based on hemodynami c criteria. (C) 1999 by The American College of Obstetricians and Gynecolog ists.