Introduction:
Twin-to-twin transfusion syndrome (TTTS) is associated with increased
risk for fetal or neonatal death in one or both twins as well as with
increased risk for long term adverse neurological
outcomes.1-6 One of the most frequent approaches to
evaluate TTTS severity and progression is the Quintero classification
system, which is based on sonographic and Doppler findings in the donor
and recipient twins.7;8 This TTTS staging system is
widely used because of its simplicity. However, there are conflicting
reports on whether or not the Quintero staging system is predictive of
fetal or neonatal survival.7-11 Fetal echocardiography
has been used to further stratify TTTS severity and to determine the
adequate timing for laser photocoagulation of placental
anastomoses.12-15 However, the largest series for the
management of TTTS published to date did not include fetal
echocardiography information.7;16;17 This is
presumably because its role in the evaluation of TTTS severity remains
controversial,12-15 and because comprehensive fetal
echocardiography may not always be available prior to laser surgery.
We previously reported that small intertwin differences in impedance to
blood flow in the umbilical arteries (UA) among TTTS cases with Quintero
Stage I or II is associated with infant survival independent from
gestational age at delivery, Quintero stage, selective fetal growth
restriction (sFGR) and other confounding variables.9This study is designed to determine the role of intertwin differences in
the UA pulsatility index (DUAPI) in predicting infant survival among
TTTS cases with Quintero stages III or IV.