Umbilical Cord Diameter at Early Second Trimester: Relation to Trisomy 21

Abstract

Background: To compare the umbilical cord diameter (UCD) at early second trimester (at
17–19 weeks of gestation) in trisomy 21 and normal fetuses and determined value of measuring
UCD in screening trisomy 21.

Methods: This was a case–control study. The UCD was measured
in 39 fetuses with trisomy 21 (documented by chorionic villus sampling or amniocentesis) and 39
fetuses in control group at 17–19 weeks of gestation. The control groups were low‑risk fetuses for
aneuploidy in routine screening and were shown not to have aneuploidy after birth.

Results: Mean
of UCD in fetuses with trisomy 21 was lower than normal fetuses, but there were no significant
differences between them (7.48 ± 0.99 mm vs. 7.66 ± 0.91 mm; P = 0.41). Mean of UCD had no
significant difference between other maternal variable, for example, body mass index and obstetric
history. Mean of UCD among mothers who had previous cesarean section was significantly lower
than without it (7.21 ± 0.97 vs. 7.71 ± 0.97; P = 0.03).

Conclusions: At 17–19 weeks of gestation,
the UCD of fetuses with trisomy 21 is thinner than normal, but the importance of this difference is
too small for using this measurement in screening.

Keywords: Aneuploidy, fetal screening, second trimester, trisomy 21, umbilical cord diameter