Increased fetal nuchal translucency: possible involvement of early cardiac failure

The ultrasonographic measurement of nuchal translucency thickness at 10-13 weeks of gestation is accepted as an efficient method of screening for chromosomal abnormalities. However, the underlying mechanism producing increased nuchal translucency thickness is still poorly understood. The purpose of this study was to investigate the possible contribution of impaired cardiac function to such an increase, by studying the 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 and pulsed Doppler ultrasound were also used to evaluate different hemodynamic parameters in the ductus venosus: maximum systolic and diastolic velocities, pulsatility index, lowest forward velocity during atrial contraction and fetal heart rate. Fetal nuchal translucency thickness of > or = 3 mm was found in 17 cases; in five of them there were chromosomal anomalies: four trisomy 21 and one trisomy 18. Of interest is the finding that in the five chromosomally abnormal fetuses with increased nuchal translucency thickness, the forward velocity during atrial contraction was consistently less than 2 cm/s (p < 0.001). This impairment of atrial contraction may well implicate cardiac failure and/or heart defects in the pathogenesis of increased nuchal translucency thickness in the first trimester of pregnancy. Furthermore, nuchal translucency may prove to be a sensitive marker for the early identification of fetal cardiac anomalies.