95th percentile- +- PolyhydramniosEducational points:# Lemon sign:- Concave/linear frontal contour abnormality located at coronal suture strongly associated with spina bifida.# Banana sign:- Cerebellum wrapped around posterior brainstem + obliteration of cisterna magna secondary to small posterior fossa + downward traction of spinal cord in Chiari II malformation.# Key points about Obstetric color Doppler study:- Assessment of flow in MCA is important parameter to diagnose fetal anemia.- Assessment of flow in umbilical vessels is important parameter to diagnose fetoplacental insufficiency.- Reduced diastolic flow in umbilical artery is the earliest sign of fetoplacental insufficiency.- Reversal of flow in umbilical artery (as well as pulsatile flow in umbilical vein) is the most ominous sign and may indicate impending fetal death.">