Single Umbilical Artery


Reviewed by Carl Kuschel
Clinical Guidelines Back Newborn Services Home Page

Single Umbilical Artery (SUA) is a common congenital abnormality, often also called a 2-vessel cord. Isolated SUA occurs in up to 2% of all liveborn infants.1 It may be detected antenatally, or discovered upon examination of the infant at delivery.

The majority of SUA occur as an isolated anomaly. However, SUA may be associated with other structural or chromosomal anomalies.2 The risk of a chromosomal abnormality is 10-times higher in infants with a SUA.3

The median incidence of other major abnormalities in liveborn infants with a SUA is approximately 27% (range 21.6-32.2%). [1] The median incidence of occult renal abnormalities (vesicoureteric reflux, hypoplastic kidneys, absent kidney, or multicystic kidney) in otherwise normal infants with SUA in this meta-analysis was 5%.

In the absence of previously demonstrated physical abnormalities on antenatal ultrasound screening, there is little yield in obtaining investigations following delivery in infants without examination findings suggesting other anomalies.4


  1. Check if antenatal ultrasound scans demonstrated any other abnormalities
  2. Examine the baby for dysmorphic features, abdominal masses, or cardiac disease
  3. If no other abnormalities are found on examination, no investigations are required.
  4. If there is suspicion of other abnormalities, appropriate investigations (imaging, karyotype) should be arranged.


1 Thummala MR, Raju TNK, Langenberg P. Isolated single umbilical artery anomaliy and the risk for congenital malformations: a meta-analysis. J Pediatr Surg 1998;33:580-5.
2 Gossett DR, Lantz ME, Chisholm CA. Antenatal diagnosis of single umbilical artery: Is fetal echocardiography warranted? Obstet Gynecol 2002;100:9038
3 Prucka S, Clemens M, Craven C, McPherson E. Single umbilical artery: What does it mean for the fetus? A case-control analysis of pathologically ascertained cases. Genet Med 2004:6(1):547.
4 Parilla BV, Tamura RK, MacGregor SN, Geibel LJ, Sabbagha RE. The clinical significance of a single umbilical artery as an isolated finding on prenatal ultrasound. Obstet Gynecol 1995;85:570-2.