Follow Your Nose Repeat Nasal Bone Evaluation in First-Trimester Screening for Down Syndrome

ObjectiveExamine whether repeat nasal bone evaluation following an absent/uncertain nasal bone on first-trimester screening (FTS) improves Down syndrome (DS) screening specificity. MethodsA retrospective chart review of FTS sonograms in one center from January 2015 to January 2018 was performed. Data was extracted for those with an absent/uncertain nasal bone. Repeat evaluations were offered. ResultsOf 6780 FTS sonograms, 589 (8.7%) had an absent/uncertain nasal bone. Upon repeat exam, 268/376 (71.3%) had a present nasal bone. Compared with Black patients, patients of other ethnicities were more likely to have a present nasal bone on exam 2 (P < .00001). Of 268 patients with a present nasal bone on exam 2, 37 (13.8%) had an abnormal DS risk following exam 1; 34/37 (91.9%) normalized following nasal bone visualization, dropping the screen positive rate to 1.1%. ConclusionRepeat nasal bone examination is beneficial in refining DS risk assessment and improves the specificity of FTS.

Automated summary

This study found that repeat evaluation of the nasal bone in pregnant women with an absent/uncertain nasal bone during first-trimester screening improves the specificity of Down syndrome screening.