Objective: To explore the sonographic vascular architecture and the hyaluronan amount and distribution of umbilical cords of healthy and trisomy 21 fetuses in early gestation.
Material and methods: Umbilical cord sonographic morphology and morphometry of 112 consecutive normal fetuses and 11 trisomy 21 fetuses were assessed between 10 and 15 weeks of gestation. The umbilical coiling index was defined as the reciprocal of the length of one complete coil measured in a longitudinal section of the umbilical cord. The umbilical coiling angle was defined as the maximum angle between the long axis of the umbilical cord and that of the umbilical arteries. Three umbilical cord samples obtained from Down syndrome fetuses and one from a healthy fetus after voluntary termination of pregnancy at 13 weeks of gestation were used for biochemical analysis. Quantitative hyualuronan content and tissue distribution was studied using fluorophore-assisted carbohydrate electrophoresis (FACE) analysis and staining methods using biotin-labeled hyaluronan-binding protein (bHABP), respectively.
Results: A significant correlation was present between gestational age and both the umbilical coiling index (r=-0.56, p<0.001) and the umbilical coiling angle (r=-0.43, p<0.001). The proportion of uncoiled umbilical cords was significantly higher in Down syndrome fetuses than in healthy fetuses [8/112 (7.1%) vs. 4/11 (36.4%), p<0.05]. Biochemical analysis demonstrated a higher amount and a different distribution of hyaluronan in trisomy 21 umbilical cords compared to healthy fetuses.
Conclusion: The umbilical cord of Down syndrome fetuses in early gestation shows peculiar sonographic vascular features and quantitative alterations of the Wharton's jelly hyaluronan.