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Updated: May 10, 2026

Guide Wire Assisted Catheterization and Colored Dye Injection for Vascular Mapping of Monochorionic Twin Placentas
Published on: September 5, 2011
Twin pregnancies discordant for single umbilical artery
Benjamin D Byers1, George R Saade, Hassan M Harirah
1Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, University of Texas Medical Branch, Galveston, Texas, USA. benjamin.byers@yahoo.com
Objective:
To evaluate the perinatal outcomes in twin pregnancies discordant for single umbilical artery (SUA).
Study Design:
This was a retrospective cohort study. Our database was searched for all cases of twin gestation and SUA from 1997-2009. We reviewed all the maternal and neonatal records and placental pathology reports. The outcomes of the SUA fetuses were compared to that of their co-twins with a 3-vessel cord (3VC). Paired t test and chi2 tests were used for statistical analyses.
Results:
We identified 29 cases of twin pregnancies discordant for SUA out of 60,989 ultrasound patients. There were no differences in the prevalence of coexisting anomalies (34% vs. 21%, p = 0.38) between the SUA fetus and the 3VC fetus. The SUA fetus was found to have significantly lower mean birth weight (1,784 +/- 765 g vs. 2,053 +/- 668 g, p = 0.001), 1-minute Apgar score (6.83 +/- 1.89 vs. 7.62 +/- 1.18, p = 0.037), and umbilical artery cord pH (7.27 +/- 0.06 vs. 7.31 +/- 0.07, p = 0.001). The SUA fetus was smaller 79% of the time (p < 0.0001). The SUA fetus achieved a significantly lower percentile (12.77% +/- 21.8 vs. 32.00% +/- 27.56, p = 0.002) when calculating the customized growth potential.
Conclusion:
The fetus affected by an SUA in a twin gestation has impaired fetal growth and neonatal outcomes when compared to its 3VC counterpart.
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