Ans. is b i.e. Choroids plexus cyst Abnormalities associated with Down's syndrome (as listed in Benacerraf and Callen). Brachycephaly (sho frontal lobe) Ventriculomegaly Flat facies, small earsdeg Increase nuchal fold thickness Absent nasal bone Cystic hygroma (more associated with trisomy 18) Sho humerus and femur Clinodactyly Hypoplasia of middle phalanx of 5th digitdeg Single transverse palmar crease Sandal foot--i.e. widened gap between 1st and 2nd toe. Congenital hea defects (CHD) : -- Atrioventricular canal defect (Most common hea defect in Down's syndrome)deg -- VSD -- ASD Esophageal atresia and duodenal atresiadeg Diaphragmatic herniadeg Renal pyelectasis (Mild renal pelvis dilation) Hyperechoic bowel Single umbilical aerydeg Widened iliac angle. As far as Choroid plexus cyst is Concerned : -Several investigators have suggested that choroids plexus cysts are also associated with an increased risk of trisomy 21. However, our group demonstrated that the frequency of choroids plexus cysts among fetuses. with trisomy 21 was the same as that among fetuses without trisomy 21, suggesting that the presence of choroid plexus cysts should not increase a patient's calculated risk of having a fetus with Down syndrome. This is in agreement with the work from Gupta and co-workers, who repoed a 1 in 880 risk of Down syndrome among fetuses with isolated choroid plexus cysts detected antenatally." "The presence of a cyst in the choroid plexus in an axial view through the upper poion of fetal head has been correlated with the increased risk of Trisomy 18." Choroid plexus cysts are found to be associated with trisomy 18 (occurring in nearly 30% of cases of trisomy 18). Choroid plexus cysts are also found in 0.7 to 3.6% of normal second trimester fetuses.