The performance of an intermediate 16th‐week ultrasound scan for the follow‐up of euploid fetuses with increased nuchal translucency

Objective The objective of the study is to assess the utility of an intermediate ultrasound scan at 16 +0 to 18 +6  weeks of gestation in euploid fetuses with increased nuchal translucency ≥ 3.5 mm. Methods Three hundred eighty‐nine fetuses with nuchal translucency (NT) ≥ 3.5 mm were identified in two prenatal centers between January 2008 and December 2012. Pregnancy work‐up included karyotyping, monthly detailed ultrasound scan starting with a 16th‐week scan, a cardioechography, and a genetic counseling. Abnormal findings and pregnancy outcomes were analyzed retrospectively. Results Of the 389 fetuses included, 52% had normal karyotype. Among euploid fetuses, 51 (30.7%) structural defects were identified overall. First‐trimester scan was useful to identify 16 of the major defects (31.3%), and the 16th‐week scan was useful to identify an additional 21 of them (41.2%), whereas the 22nd‐week pregnancy scan discovered an additional 14 (27.4%). Structural defects discovered with the 16th‐week scan were cardiac defects ( n  = 7), polymalformative syndromes ( n  = 3), left diaphragmatic hernias ( n  = 3), limbs abnormalities ( n  = 2), genitourinary ( n  = 2), microretrognathism ( n  = 2), hydrops ( n  = 1), and exomphalos ( n  = 1). If the intermediate scan was normal, the chances of a favorable outcome were as high as 85% and were close to 100% after 20 weeks, irrespective of initial NT. Conclusion The intermediate ultrasound was useful in fetuses with increased NT pregnancy work‐up. © 2015 John Wiley & Sons, Ltd.