What is the NT test for at 12 weeks of pregnancy?

Almost all pregnant mothers go for a prenatal check-up when they are 12 weeks pregnant. The most important test at this time is to check the NT value. NT is the abbreviation of nuchal translucency, which refers to the "neck transparent layer", that is, the maximum thickness between the skin and the subcutaneous soft tissue of the fetal cervical vertebrae. In fact, many mothers who have done this pregnancy test do not know what NT is?

What are the NT tests for 12 weeks of pregnancy?

NT test refers to the fetal nuchal translucency, which refers to the thickness of the fluid accumulation in the subcutaneous tissue at the back of the fetal neck. By checking the thickness of the fetal nuchal translucency, the fetal chromosomal diseases can be diagnosed at an early stage and fetal abnormalities caused by various reasons can be discovered at an early stage, such as: fetal spina bifida, fetal spinal protrusion, hydrocephalus, lateral ventricle enlargement, posterior cranial cistern thickening, heart malformations, etc.

NT is a transparent protein membrane that circulates around the back of the fetus' neck during the 10-13th week of pregnancy. Its thickness is proportional to the fetal DS defect and can be accurately measured by ultrasound imaging. The thickness of the fetal neck transparent tissue refers to the thickness between the fetal bone soft tissue and the skin. It is considered to be the most effective indicator for screening fetuses with Down syndrome, because most patients with Down syndrome have edema of the soft tissue in the neck, while normal fetuses do not have this abnormal clinical symptoms. Some people think that the reason for the thickening of the fetal neck translucent tissue may be that the fetus has cardiovascular malformations due to chromosomal abnormalities, resulting in early severe heart malformations such as ventricular septal defect, aortic stenosis, and heart failure caused by maldevelopment of blood vessels and lymphatic vessels in the face and neck; there are also reports that if the fetus is found to have abnormal thickness of the fetal neck translucent tissue in the early stages of pregnancy, the chance of having Down syndrome or other trisomy syndromes may be more than 13 times, and it has diagnostic significance between 10 and 22 weeks of pregnancy, but the diagnostic value is greatest between 10 and 14 weeks of pregnancy.

Necessity of NT

In China, doctors generally recommend that key Down syndrome patients undergo a nuchal translucency scan, such as pregnant women over 35 years old, pregnant women who have previously given birth to a baby with Down syndrome, or pregnant women with a family history of giving birth to a baby with Down syndrome. Although the nuchal translucency scanner cannot accurately determine whether the fetus is sick, it can help pregnant women decide whether further diagnostic tests are needed.

The nuchal translucency scanner is a way to assess whether the fetus is likely to have Down syndrome and is a screening method. NT tests are different from confirmatory tests such as chorionic villus aspiration biopsy or amniocentesis. They can provide a clear diagnosis, but NT tests can only indicate risks.

The accuracy of the nuchal translucency examination is determined by many factors, including the level of the ultrasound doctor and the accuracy of the scanner used, so the examination results cannot be guaranteed to be 100% accurate.

The NT test can only provide a reference for whether further prenatal examinations are needed. It cannot be used to determine whether the fetus has any abnormalities based on the ultrasound screening results. To determine whether the fetus has chromosomal abnormalities, hCG sampling or amniocentesis is still required for further sex chromosome analysis.