INTRODUCTION
Intrauterine growth restriction (IUGR) due to placental insufficiency is predominantly a vascular disorder. It is associated with adverse short term and long term outcomes [1, 2, and 3]. Fetal well being tests and indices could be roughly classified as chronic and acute. Chronic indices (abnormal doppler flow in umbilical artery(UA) or middle cerebral artery(MCA) become progressively abnormal due to increasing hypoxemia or hypoxia while acute indices(reversal in ductus venosus (DV) represent severe fetal hypoxia and metabolic acidosis and usually precede fetal death in few days . Doppler examination of the umbilical artery (UA) and the middle cerebral artery (MCA) have proved to be good predictors of adverse perinatal outcome. However, because the risks of iatrogenic prematurity are very high before 32 weeks’ gestation, further doppler parameters are needed to assess fetal compromise. Venous Doppler patterns together with gestational age (GA) at delivery have been advocated as the best predictors of adverse perinatal outcome in IUGR fetuses [4] however are too late and represent the failed fetal defence mechanism against hypoxia [5]. Thus there is a gap of few days to weeks between these early and late signs during which new parameters are needed to document the progression of fetal deterioration in more better and accurate way. This will help to identify those fetuses whose defence mechanism against severe hypoxia and acidemia are about to fail but yet not failed.
Aortic isthmus blood flow pattern reflects the balance between both ventricular outputs and the existence of differences in the impedance in either vascular system [6]. Its role as a short term marker of adverse perinatal outcome [7] and a long-term predictor of neurodevelopmental outcome [8, 9] have been proposed. Abnormal AoI impedance indices occur prior to cardiac decompensation [10]. Retrograde flow in aortic isthmus occurs commonly after the abnormal flow in the umbilical artery and before abnormal ductus venosus flow .Thus the aim of this study was to evaluate the association between AoI doppler changes and adverse perinatal outcome in growth-restricted fetuses and neurodevelopemental outcome between 2-4yrs of age and to find out whether can we use retrograde flow in aortic isthmus as an additional trigger to deliver growth restricted fetuses between 30-34 weeks of gestation where yet there is a dilemma between continuing the surveillance vs. delivering prematurely due to lack availability of clear indicators .