INCREASED FETAL NUCHAL TRANSLUCENCY - POSSIBLE INVOLVEMENT OF EARLY CARDIAC-FAILURE

The ultrasonographic measurement of nuchal translucency thickness at 1 0-13 weeks of gestation is accepted as an efficient method of screenin g for chromosomal abnormalities. However, the underlying mechanism pro ducing increased nuchal translucency thickness is still poorly underst ood. The purpose of this study was to investigate the possible contrib ution of impaired cardiac function to such an increase, by studying th e venous return in the ductus venosus, using Doppler ultrasound. In a total of 65 fetuses, nuchal translucency thickness was measured at 10- 13 weeks of gestation by means of a transvaginal probe. Color-coded an d pulsed Doppler ultrasound were also used to evaluate different hemod ynamic parameters in the ductus venosus: maximum systolic and diastoli c velocities, pulsatility index, lowest forward velocity during atrial contraction and fetal heart rate. Fetal nuchal translucency thickness of greater than or equal to 3 mm was found in 17 cases; in five of th em there were chromosomal anomalies: four trisomy 21 and one trisomy 1 8. Of interest is the finding that in the five chromosomally abnormal fetuses with increased nuchal translucency thickness, the forward velo city during atrial contraction was consistently less than 2 cm/s (p < 0.001). This impairment of atrial contraction may well implicate cardi ac failure and/or heart defects in the pathogenesis of increased nucha l translucency thickness in the first trimester of pregnancy. Furtherm ore, nuchal translucency may prove to be a sensitive marker for the ea rly identification of fetal cardiac anomalies.