First-trimester umbilical cord diameter: a novel marker of fetal aneuploidy.

To compare the umbilical cord diameter at 10-14 weeks of gestation of chromosomally normal and abnormal fetuses. METHODS: In a consecutive series of women, who were undergoing routine sonographic evaluation at 10-14 weeks of gestation, umbilical cord diameter and nuchal translucency were measured. Reference ranges for umbilical cord diameter according to gestational age and crown-rump length were constructed. Fetal karyotype was obtained at chorionic villus sampling, amniocentesis or at delivery in newborns with features suspicious for chromosomal abnormalities. RESULTS: During the study period, 784 patients met the inclusion criteria. Of these, a fetal or placental chromosomal abnormality was present in 17 cases. The mean umbilical cord diameter increased with gestational age (r = 0.41, P < 0.001). The proportion of fetuses with an umbilical cord diameter above the 95th centile was higher in the presence of fetal or placental chromosomal abnormalities than in normal fetuses (5/17 vs. 39/767, P < 0.01). Among fetuses with an abnormal fetal or placental karyotype, nuchal translucency was above the 95th centile for gestational age in 10 cases. When only fetal chromosomal abnormalities were considered (n = 14), the combined detection rate was 85.7%(12/14). CONCLUSIONS: Sonographic assessment of the umbilical cord in early gestation appears to identify a subset of fetuses at increased risk of chromosomal abnormaliti