What does an abnormal nt value indicate

Abnormal NT values may indicate the risk of chromosomal abnormalities, congenital heart disease, or other structural abnormalities in the fetus. NT examination is a method of measuring the thickness of the nuchal translucency of the fetus through ultrasound. The main influencing factors include measurement errors, fetal position, gestational age calculation deviations, chromosomal abnormalities, and fetal cardiovascular development abnormalities.

1. Measurement Error

NT inspection has high requirements for the accuracy of ultrasound equipment and the technical skills of operators. Excessive stretching or bending of the fetal neck, as well as non-standard ultrasound sections, may result in larger measurement values. It is recommended to choose a hospital with prenatal diagnosis qualifications for re examination to avoid misjudgment caused by technical factors.

2. Fetal Position

During the examination, if the fetus is in a special position, it may temporarily affect the thickness of the nuchal translucency. When the fetal neck is compressed or in a supine position, temporary obstruction of lymphatic return may lead to thickening of the NT. It is recommended to have a follow-up examination every 1-2 weeks in this situation, and most cases can be restored to normal.

3. Pregnancy week deviation

NT examination should be strictly performed between 11-13 weeks and 6 days of pregnancy. Errors in the calculation of gestational age can cause the measurement to lose its reference value. Mistakenly remembering the last menstrual cycle, irregular menstruation, or delayed ovulation can all lead to misjudgment of gestational age, and early ultrasound should be used to recheck the gestational age.

4. Chromosomal abnormalities

21 trisomy syndrome, 18 trisomy syndrome and other chromosomal diseases are often accompanied by NT thickening. Abnormal thickening of NT values may indicate a risk of fetal aneuploidy, which requires further diagnosis through non-invasive DNA or amniocentesis. This type of situation usually requires evaluation by genetic counseling experts.

5. Cardiovascular abnormalities

Fetal cardiac developmental defects may lead to lymphatic drainage disorders, manifested as NT thickening. Commonly seen in congenital heart diseases such as atrioventricular septal defect and transposition of the great arteries. It is recommended to undergo a specialized fetal cardiac ultrasound examination, with the participation of a pediatric cardiologist for evaluation. When abnormal NT values are detected, there is no need for excessive anxiety, but a systematic investigation of the cause is required. Suggest completing follow-up examinations such as fetal ultrasound and non-invasive prenatal testing, and conducting interventional prenatal diagnosis if necessary. Maintain a regular schedule during pregnancy, avoid exposure to teratogenic substances, and follow medical advice to supplement with nutrients such as folic acid. Regular prenatal check ups help to dynamically observe fetal development, and most fetuses with mild NT thickening but normal follow-up examinations have a good prognosis.