Objective:

To know the perinatal outcome based on nasal bone evaluation as an aneuploidy marker.

Methods:

From 1006 pregnant women, 607 met the inclusion criteria for this prospective, descriptive, correlational not causal research correlating nasal bone absence / presence with Down syndrome through prenatal / postnatal fetal karyotype and neonatal clinical examination. Absolute frequencies and percentages, nasal bone performance as a diagnostic test (Youden índex), sensitivity, specificity, positive predictive value, negative predictive value, likelihood ratios positive and negative, were calculated.

Results:

1.48 % was the Down syndrome prevalence on the sample. The nasal bone absence as an isolated marker obtained an 0,55 Youden index (0.23 to 0.88 ), sensitivity 55,56%, specificity 99,50%, positive predictive value 62,5%, negative predictive value 99,33%, likelihood ratios positive (absent nasal bone) 111, (95% CI 31-394) and likelihood ratios negative (nasal bone present ) 0,45 (95% CI 0 22 -0.93).

Conclusions:

The nasal bone absence in first trimester increases Down syndrome risk 111 times and nasal bone presence decreases it with poor performance as a diagnostic test, so it should be considered a screening test and a secondary marker. Recommendations correlate these results with other markers to improve detection rates and quantify nasal bone measurements in order to make nasal bone nomograms in first trimester pregnancies.