Predictive value of fetal nuchal translucency

To determine the predictive value of fetal nuchal translucency (NT) measurements in the detection of chromosomopathy.

The investigation of NT included 317 pregnant women with singleton pregnancies of gestational age of 11 to 14 weeks with pathological karyotype. The control group consisted of pregnant women whose amniocentesis findings indicated a normal fetal karyotype.

The median value of NT in the control group was 1.92 +/- 0.39 mm, and in the group with pathological fetus karyotype findings it was 2.49 +/- 0.37 mm (p < 0.05). The median value of crown-rump length was 64.83 +/- 8.23 mm and 60.12 +/- 8.48 mm in the control group and in the group with pathological karyotype, respectively. The gestational age in the control group was 87.10 +/- 87.10 days, while in the pathological group it was 85.69 +/- 3.98 days, which indicated the homogeneity of the investigated sample (p > 0.05). The probability for a patient with negative NT findings to be healthy was 1.0, NT sensitivity as a marker for chromosomopathy was 1.0. The rate of false positive findings was 0.026. The specificity of NT as a marker for chromosomopathy was 0.97.

Normal NT findings could be considered reliable ultrasonographic markers in the assessment of the absence of chromosomopathy. Pathological findings, given the low positive predictive value of NT must be interpreted in the context of other prenatal tests before the pregnant woman is advised to undergo invasive prenatal diagnosis.