/kloc-the standard value of 0/3 gestational age nt. Fetuses with Down syndrome will have subcutaneous effusion, so the skin behind the neck will be thicker. If the thickness of fetal neck skin detected by NT exceeds the standard value, it may be related to abnormal fetal karyotype and other structural abnormalities. The thicker NT, the greater the probability of abnormal fetal structure and chromosome. In addition to detecting the risk of chromosomal abnormalities, the thickening of fetal neck zona pellucida is also related to congenital heart disease.
From10 to14 weeks of pregnancy, more than 80% of the fetal neck translucent thickness will increase. In medicine, NT value is generally 3mm as the dividing line. If it exceeds 3mm, there is an emergency to pay attention to. To be on the safe side, the limit value of 3mm is sometimes shortened to 2 mm, that is to say, in many cases, when the measured NT value is greater than 2.5mm, many parents will conduct more in-depth consultation for the health of the fetus. If the NT test results are beyond the standard range, it is suggested that pregnant women should have a follow-up abnormal examination to further confirm the risk of fetal abnormality so as to take countermeasures as soon as possible.
The necessity of NT examination is that the scanning of the posterior cervical zona pellucida is a method to evaluate whether the fetus may have Down syndrome, and it is also a screening method. Nt examination is different from diagnostic examination such as chorionic biopsy or amniocentesis, which can provide definite diagnosis results, but NT examination can only indicate risks.
The accuracy of cervical zona pellucida examination is determined by many factors, including the level of B-ultrasound doctors and the accuracy of scanners used, so the accuracy of 100% cannot be guaranteed.
NT examination can only provide reference for further prenatal diagnosis, and can not judge whether the fetus is abnormal according to the results of ultrasound screening. To judge whether the fetus has chromosomal abnormalities, it is still necessary to make further chromosomal analysis by chorionic sampling or amniocentesis.
NT examination countermeasures If the NT measurement value of pregnant mothers is 3.4mm, pregnant mothers need not worry. First of all, this value does not necessarily increase; Secondly, even if it does rise, NT is only a screening test, not a confirmed test, so it is not an indication of termination of pregnancy. NT measuring 3.4mm does not mean that there is something wrong with the fetus. If possible, you can do a non-invasive genetic examination or an invasive prenatal diagnosis to see if there are any chromosomal abnormalities.
If the chromosome is normal, then we should pay attention to the follow-up examination of fetal echocardiography. At the same time, NT thickening may be related to other malformations, so it is also an indication of three-dimensional B-ultrasound examination in the second trimester.
The detection time of cervical zona pellucida scan is in the first trimester. At this time, if abnormalities are found, pregnant women can also do villus biopsy in time and get results as soon as possible. If pregnant women don't know what to do, they can wait until 16 weeks of pregnancy to do amniocentesis, or they can directly consult a doctor for more information and suggestions.
The occurrence of Down syndrome should focus on prevention, and every pregnant woman should listen to the guidance of doctors and do a good job in prenatal screening and prenatal diagnosis in order to have a healthy child and be responsible for family happiness.