Objective: This study was undertaken to study the frequency and cause of fused umbilical arteries (FUAs).
Study design: Umbilical cord on the placental side was carefully examined for FUAs by continuous interval sections.
Results: The frequency was 3.1% or 22 in 702 infants with the frequency in female infants of 4.1% being significantly higher than that in male infants of 2.0%. The mean distance of fused points was 2.3 +/- 1.6 cm from placental cord insertion. Five of 22 cases showed both arterial fusion and division in the same umbilical cord. Marginal and velamentous insertions were significantly associated with FUAs. Gestational age, birth weight, and placental weight of 22 cases were within normal range.
Conclusion: Single umbilical artery should be confirmed by 2 or 3 sections of umbilical cord because of the high frequency of FUA on the placental side.