"When the nuchal translucency thickness is more than 3.5 mm the chances of baby developing chromosome and abnormalities and structural defects or genetic problems increase. But the majority of these babies will grow normally without any problems. When the NT thickness is more we need to do further investigations like amniocentesis which is an NT test"

"The combined First Trimester screening report gives us a risk value. It can be either high risk low risk or intermediate risk low risk means the risk is more than 1 in 1000. If it saves low risk that means the chances of your baby getting chromosomal problems is less like and when the risk is intermediate risk which is between 100 to 1000 we should test it further. With either NIPT or amniocentesis and if the risk shows as high risk that means which when it is less than one 100 we need to definitely go for invasive testing called amniocentesis. If the risk is high it means the probability of your baby getting chromosomal problem is high. So we need to confirm whether it is really an abnormality or if it is is a false positive. For that we need invasive testing either chorionic villus sampling or amniocentesis based on the period of gestation. If it crosses 16 weeks we go for amniocentesis and if it is less than 16 weeks we go for chorionic villus sampling and when the NIPT report shows it has low risk that means the chances of baby getting chromosomal problem is less likely and after the high risk report in the combined first trimester screening. If the NIPT shows it as low risk that means the probability is less likely if it again shows as high risk in NIPT we need to definitely confirm with invasive testing again"

"So the components of combined First Trimester screening are maternal age, ultrasound parameters and the lab parameters. The risk given by just mother's age alone is around 30 to 50% accurate and with just the lab parameters that is beta hCG and PAPP - A it is around 50 to 70%. When we combine with the ultrasound parameters the maternal age and the lab parameters the accuracy is around 90% we also combine few markers in the ultrasound that is Tricuspid doppler and nose bone the risk accuracy goes up to 95%"

"The combined First Trimester screening that is NT scan and double marker test has an accuracy of around 90% and a false positive rate of around 3%. It doesn't give a result with an accuracy of 100% and if required while we go for further testing the false positive rate is around 3% and false negative rate is also around 1 to 3 %"

"There are no risks associated with anti scan as such. There are few limitations that is the NT scan is not 100% accurate in diagnosing chromosomal abnormalities . It can only predict the chances of occurrence in the baby. The confirmation test is always a invasive testing called amniocentesis or chorionic villi sampling. We do it only when there is a indication for that like when the risk is high or whether there is any previous abnormal history or when there is any structural abnormalities in the baby or when the entry is more than 3.5 mm"

"There are no risk associated with NT scan. It is absolutely safe during pregnancy. So there are few limitations to the NT scan that is ancan is not 100% accurate in diagnosing chromosomal abnormalities. We can only get detect to the accuracy of around 90% when there is a combined first trimester screening the confirmation is always by invasive testing called chonic villi sampling or amniocentesis wherein we place a very thin needle into the uterine cavity and we take a small amount of amniotic fluid for testing. This is the final confirmation test we do it when the risk is high or when there is any structural abnormality in the baby or when the nuchal translucency is more than 3.5 million"