Pregnancy Outcome in Isolated Single Umbilical Artery

Abstract

Our objective was to determine whether the rate of small for gestational age (SGA) infants and adverse perinatal outcome are increased in pregnancies diagnosed with an isolated single umbilical artery (SUA). We compared 297 pregnancies with a SUA diagnosed on routine obstetrical ultrasound with 297 pregnancies with a three-vessel cord control. Pregnancies complicated by major fetal anomalies were excluded. The rate of SGA, fetal death, and neonatal outcomes were compared between the two groups. Data analysis were performed using the T-test and chi-square test. The sample size had 80% power to detect a 50% difference between groups assuming a SGA rate of 20% in the SUA group and 10% in the control, alpha = 0.05. Among the SUA group, in 21 neonates (7.1%) the presence of a SUA could not be confirmed by postnatal examination, and 21 (7.1%) had major congenital anomalies, leaving 255 for final analysis. In the control group, 8 of the 297 (2.7%) had major congenital anomalies, leaving 289 for final analysis. The incidence of SGA neonates was 35 of 255 (13.7%) in the isolated SUA group compared with 38 of 289 (13.1%) in the control group ( P = 0.93). The composite perinatal outcomes (fetal death and/or SGA) were also similar between the groups (16.1% versus 14.5%; P = 0.72). We concluded that pregnancies with isolated SUA have a similar rate of SGA to those with 3VC. When a SUA is identified antenatally, a targeted ultrasound is warranted to rule out associated anomalies. Serial antepartum ultrasound for fetal growth is not necessary in managing pregnancies complicated by isolated SUA.

Should fetal growth be a matter of concern in isolated single umbilical artery?

“…3 Although several studies have reported diminished fetal growth in these pregnancies, [4][5][6][7][8][9][10][11][12] others have not shown differences. [13][14][15] These contradictory findings may be attributed to diverse methodological differences in the published literature.…”

“…Eleven series are based on cases diagnosed prenatally and significant differences in birth weight were demonstrated in four out of six studies that included control groups. 6,7,11,[13][14][15]18,[20][21][22][23] On the other hand, all post-natal studies have shown that birth weight is significantly lower in ISUA pregnancies compared to control pregnancies. 5,9,10,12 This is possibly related to the fact that these are the studies with greater sample size.…”

“…There was also no evidence of increased need for admission to neonatal intensive care units (Bombrys et al). 14 In fetuses with two vessels cord, compensatory mechanisms are in place to allow the single artery to meet the demands for fetal development during late pregnancy. One of these mechanisms is an increase of the arterial diameter.…”

Isolated single umbilical artery: evaluating the risk of adverse pregnancy outcome

“…Despite these associations, controversy exists regarding the clinical significance of SUA as an isolated finding in a low-risk patient population. Some of the current literature did not demonstrate an increased risk of IUGR in anatomically normal fetuses with SUA and the authors suggested that the remaining artery in SUA fetuses carries twice the blood volume of an artery in a 3VC [4,8,9]. Other studies reported that the finding of SUA is associated with increased incidence of fetal growth restriction, prematurity and perinatal mortality and recommended serial sonograms for fetal growth and close obstetric follow-up [3,[10][11][12][13].…”

Incidencia Y Asociaciones De Arteria Umbilical Única en Recién Nacidos: Maternidad Del Hospital Clínico De La Universidad De Chile, 1998-2010

“…Esta concordancia demuestra, una vez más, la importancia que la RCIU tiene como factor de riesgo para malformaciones congénitas estructurales, aneuploidías y aberraciones cromosómicas. Gran importancia también tiene el hecho de el alto porcentaje de prematuros en nuestra muestra (55,4%), aún cuando otros autores no encuentran diferencias en la prematuridad entre los niños con AUU y los normales (15). Nuestros hallazgos, sin embargo, están plenamente de acuerdo con lo reportado por otros autores (7).…”