Transient increase in nuchal translucency thickness and reversed end-diastolic ductus venosus flow in a fetus with trisomy 18.

In a twin pregnancy discordant for trisomy 18, the affected fetus at 13 weeks' gestation had an increased nuchal translucency thickness and reversed end-diastolic ductus venosus flow. At 20 weeks' gestation there was no nuchal edema and Doppler study of the central venous vessels demonstrated normal waveforms. The findings support the hypothesis that one of the mechanisms in the development of increased nuchal translucency is temporary cardiac strain.