- SANTILLAN, DIEDRE FLEENER, STEPHEN HUNTER, JEROME YANKOWITZ, University of Iowa, Iowa City, Iowa OBJECTIVE: A single umbilical artery (SUA) occurs in up to 2.0% of fetuses. Increased rates of other congenital malformations, chromosomal abnormalities, perinatal mortality, growth restriction and preterm labor have been associated with SUA. An absent left umbilical artery (UA) has been associated with an increased rate of malformations. Other studies refute this. In this study, the largest to date, we investigate whether the laterality of the missing UA has an association with the rate of congenital malformations, chromosomal abnormalities, or Doppler abnormalities. STUDY DESIGN: Fetuses with a SUA were retrospectively identified from the University of Iowa obstetric ultrasound database (1989-2002). The ultrasound reports and medical records of these patients were evaluated for laterality of the absent UA, congenital malformations, chromosomal abnormalities and UA Doppler abnormalities. To control for confounding variables, demographic, maternal, and other obstetric variables were also obtained. Binary logistic regression and 2 tail Fisher exact test were performed with 0.05. RESULTS: Prenatal diagnosis of SUA was made in 230 fetuses. An absent left and right UA were identified in 86 (37%) and 63 (28%) patients respectively. Laterality was not specified in 81 (35%) patients. Overall, congenital malformations were found in up to 21% of the fetuses. The rates of UA Doppler abnormality and birth defects documented postpartum were 8.3% and 47% respectively. With regard to biometry, placental appearance, amniotic fluid index, and congenital malformations, there were no statistically significant differences between those with a left or right UA missing. Chromosomal abnormalities, UA Dopplers, and documented postpartum birth defects were not statistically different between those with absence of the left or right UA. CONCLUSION: Our data support other studies which conclude that the laterality of the absent UA has no effect on the rate of congenital malformations and chromosomal abnormalities. Furthermore, our study concludes that laterality has no effect on UA doppler values.