Official reprint from UpToDate®
www.uptodate.com ©2016 UpToDate®

Single umbilical artery

Martin L Gimovsky, MD
Eva Tejero Rosa, MS, CGC
Section Editors
Deborah Levine, MD
Louise Wilkins-Haug, MD, PhD
Deputy Editor
Vanessa A Barss, MD, FACOG


The umbilical cord typically contains two arteries and one vein. Single umbilical artery (SUA) refers to a variation of umbilical cord structure in which there is only one umbilical artery. The incidence ranges from 0.5 to 6 percent of pregnancies, depending on the population studied.

SUA is an isolated finding in approximately 65 percent of affected fetuses [1]. In the remainder, SUA is associated with aneuploidy, intrauterine growth restriction, and/or additional congenital anomalies.


Between three and five weeks of gestation, the umbilical cord is formed by the fusion of the yolk sac and the body stalk [2]. During this process, the two umbilical veins fuse to form a single vein. The umbilical vein carries oxygenated blood from the placenta to the fetus. Concurrently, the umbilical arteries arise from the allantois, which is a portion of the yolk sac. The umbilical arteries carry deoxygenated blood from the fetus to the placenta.

Three mechanisms have been proposed to explain the embryogenesis of SUA: primary agenesis of one of the umbilical arteries, persistence of the original single allantoic artery of the body stalk, and secondary atresia or atrophy of a previously normal umbilical artery [3]. The latter mechanism is probably the most common, and is strongly supported by the detection of muscular remnants in approximately 40 percent of umbilical cords from cases of SUA undergoing microscopic examination [4].

SUA may be classified into four types based upon the likely developmental etiology [5,6]:


Subscribers log in here

To continue reading this article, you must log in with your personal, hospital, or group practice subscription. For more information or to purchase a personal subscription, click below on the option that best describes you:
Literature review current through: Jan 2016. | This topic last updated: Oct 15, 2015.
The content on the UpToDate website is not intended nor recommended as a substitute for medical advice, diagnosis, or treatment. Always seek the advice of your own physician or other qualified health care professional regarding any medical questions or conditions. The use of this website is governed by the UpToDate Terms of Use ©2016 UpToDate, Inc.
  1. Granese R, Coco C, Jeanty P. The value of single umbilical artery in the prediction of fetal aneuploidy: findings in 12,672 pregnant women. Ultrasound Q 2007; 23:117.
  2. Bianchi DW, Cromblehome TM, D’Alton ME. Fetology: Diagnosis and management of the fetal patient, McGraw Hill, New York 2000. p.827.
  3. Abuhamad AZ, Shaffer W, Mari G, et al. Single umbilical artery: does it matter which artery is missing? Am J Obstet Gynecol 1995; 173:728.
  4. Altshuler G, Tsang RC, Ermocilla R. Single umbilical artery. Correlation of clinical status and umbilical cord histology. Am J Dis Child 1975; 129:697.
  5. Persutte WH, Hobbins J. Single umbilical artery: a clinical enigma in modern prenatal diagnosis. Ultrasound Obstet Gynecol 1995; 6:216.
  6. Blackburn W, Cooley W. Umbilical cord. In: Human malformations and related anomalies, Stevenson RE, Hall JG (Eds), Oxford University Press, New York 1993. Vol 2nd, p.1275.
  7. Rembouskos G, Cicero S, Longo D, et al. Single umbilical artery at 11-14 weeks' gestation: relation to chromosomal defects. Ultrasound Obstet Gynecol 2003; 22:567.
  8. Thummala MR, Raju TN, Langenberg P. Isolated single umbilical artery anomaly and the risk for congenital malformations: a meta-analysis. J Pediatr Surg 1998; 33:580.
  9. Naeye RL. Disorders of the umbilical cord. In: Disorders of the placenta, fetus and neonate, Mosby-Year Book Inc, St Louis 1992. p.92.
  10. Leung AK, Robson WL. Single umbilical artery. A report of 159 cases. Am J Dis Child 1989; 143:108.
  11. Bernirschke K, Driscoll SG. The pathology of the human placenta, Springer, New York 1967. p.232.
  12. Heifetz SA. Single umbilical artery. A statistical analysis of 237 autopsy cases and review of the literature. Perspect Pediatr Pathol 1984; 8:345.
  13. Stout MJ, Odibo AO, Longman R, et al. The incidence of isolated single umbilical artery in twins and adverse pregnancy outcomes. Prenat Diagn 2013; 33:269.
  14. Klatt J, Kuhn A, Baumann M, Raio L. Single umbilical artery in twin pregnancies. Ultrasound Obstet Gynecol 2012; 39:505.
  15. Victoria A, Mora G, Arias F. Perinatal outcome, placental pathology, and severity of discordance in monochorionic and dichorionic twins. Obstet Gynecol 2001; 97:310.
  16. Bryan EM, Kohler HG. The missing umbilical artery. I. Prospective study based on a maternity unit. Arch Dis Child 1974; 49:844.
  17. AIUM practice guideline for the performance of obstetric ultrasound examinations. http://files.aium.org/guidelines/obstetric/imageresources.pdf (Accessed on March 03, 2011).
  18. Catanzarite VA, Hendricks SK, Maida C, et al. Prenatal diagnosis of the two-vessel cord: implications for patient counselling and obstetric management. Ultrasound Obstet Gynecol 1995; 5:98.
  19. Lubusky M, Dhaifalah I, Prochazka M, et al. Single umbilical artery and its siding in the second trimester of pregnancy: relation to chromosomal defects. Prenat Diagn 2007; 27:327.
  20. Geipel A, Germer U, Welp T, et al. Prenatal diagnosis of single umbilical artery: determination of the absent side, associated anomalies, Doppler findings and perinatal outcome. Ultrasound Obstet Gynecol 2000; 15:114.
  21. Fukada Y, Yasumizu T, Hoshi K. Single umbilical artery: correlation of the prognosis and side of the missing artery. Int J Gynaecol Obstet 1998; 61:67.
  22. Blazer S, Sujov P, Escholi Z, et al. Single umbilical artery--right or left? does it matter? Prenat Diagn 1997; 17:5.
  23. Budorick NE, Kelly TF, Dunn JA, Scioscia AL. The single umbilical artery in a high-risk patient population: what should be offered? J Ultrasound Med 2001; 20:619.
  24. Hua M, Odibo AO, Macones GA, et al. Single umbilical artery and its associated findings. Obstet Gynecol 2010; 115:930.
  25. Dagklis T, Defigueiredo D, Staboulidou I, et al. Isolated single umbilical artery and fetal karyotype. Ultrasound Obstet Gynecol 2010; 36:291.
  26. DeFigueiredo D, Dagklis T, Zidere V, et al. Isolated single umbilical artery: need for specialist fetal echocardiography? Ultrasound Obstet Gynecol 2010; 36:553.
  27. Bryan EM, Kohler HG. The missing umbilical artery. II. Paediatric follow-up. Arch Dis Child 1975; 50:714.
  28. Froehlich LA, Fujikura T. Follow-up of infants with single umbilical artery. Pediatrics 1973; 52:6.
  29. Gornall AS, Kurinczuk JJ, Konje JC. Antenatal detection of a single umbilical artery: does it matter? Prenat Diagn 2003; 23:117.
  30. Rochon M, Eddleman K. Controversial ultrasound findings. Obstet Gynecol Clin North Am 2004; 31:61.
  31. 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; 6:54.
  32. Murphy-Kaulbeck L, Dodds L, Joseph KS, Van den Hof M. Single umbilical artery risk factors and pregnancy outcomes. Obstet Gynecol 2010; 116:843.
  33. Voskamp BJ, Fleurke-Rozema H, Oude-Rengerink K, et al. Relationship of isolated single umbilical artery to fetal growth, aneuploidy and perinatal mortality: systematic review and meta-analysis. Ultrasound Obstet Gynecol 2013; 42:622.
  34. Burshtein S, Levy A, Holcberg G, et al. Is single umbilical artery an independent risk factor for perinatal mortality? Arch Gynecol Obstet 2011; 283:191.
  35. Battarbee AN, Palatnik A, Ernst LM, Grobman WA. Association of Isolated Single Umbilical Artery With Small for Gestational Age and Preterm Birth. Obstet Gynecol 2015; 126:760.
  36. Ashwal E, Melamed N, Hiersch L, et al. The impact of isolated single umbilical artery on labor and delivery outcome. Prenat Diagn 2014; 34:581.
  37. Parilla BV, Tamura RK, MacGregor SN, et al. The clinical significance of a single umbilical artery as an isolated finding on prenatal ultrasound. Obstet Gynecol 1995; 85:570.
  38. Lacro RV, Jones KL, Benirschke K. The umbilical cord twist: origin, direction, and relevance. Am J Obstet Gynecol 1987; 157:833.
  39. Raio L, Ghezzi F, Di Naro E, et al. Prenatal assessment of Wharton's jelly in umbilical cords with single artery. Ultrasound Obstet Gynecol 1999; 14:42.
  40. Chetty-John S, Zhang J, Chen Z, et al. Long-term physical and neurologic development in newborn infants with isolated single umbilical artery. Am J Obstet Gynecol 2010; 203:368.e1.
  41. Joó JG, Beke A, Papp Z, et al. Single umbilical artery in fetopathological investigations. Pathol Res Pract 2008; 204:831.
  42. Bourke WG, Clarke TA, Mathews TG, et al. Isolated single umbilical artery--the case for routine renal screening. Arch Dis Child 1993; 68:600.
  43. Chow JS, Benson CB, Doubilet PM. Frequency and nature of structural anomalies in fetuses with single umbilical arteries. J Ultrasound Med 1998; 17:765.
  44. Martínez-Frías ML, Bermejo E, Rodríguez-Pinilla E, et al. Does single umbilical artery (SUA) predict any type of congenital defect? Clinical-epidemiological analysis of a large consecutive series of malformed infants. Am J Med Genet A 2008; 146A:15.
  45. Prefumo F, Güven MA, Carvalho JS. Single umbilical artery and congenital heart disease in selected and unselected populations. Ultrasound Obstet Gynecol 2010; 35:552.
  46. Deshpande SA, Jog S, Watson H, Gornall A. Do babies with isolated single umbilical artery need routine postnatal renal ultrasonography? Arch Dis Child Fetal Neonatal Ed 2009; 94:F265.
  47. Smith DW. Recognizable patterns of human malformation, 6th, WB Saunders, Philadelphia 2006.
  48. Van den Hof MC, Wilson RD, Diagnostic Imaging Committee, Society of Obstetricians and Gynaecologists of Canada, Genetics Committee, Society of Obstetricians and Gynaecologists of Canada. Fetal soft markers in obstetric ultrasound. J Obstet Gynaecol Can 2005; 27:592.
  49. Khong TY, George K. Chromosomal abnormalities associated with a single umbilical artery. Prenat Diagn 1992; 12:965.
  50. Nyberg DA, Mahony BS, Luthy D, Kapur R. Single umbilical artery. Prenatal detection of concurrent anomalies. J Ultrasound Med 1991; 10:247.
  51. American College of Obstetricians and Gynecologists Committee on Genetics. Committee Opinion No. 581: the use of chromosomal microarray analysis in prenatal diagnosis (Reaffirmed February 2016). Obstet Gynecol 2013; 122:1374.
  52. Wapner RJ, Martin CL, Levy B, et al. Chromosomal microarray versus karyotyping for prenatal diagnosis. N Engl J Med 2012; 367:2175.
  53. Sepulveda W, Dezerega V, Carstens E, et al. Risks of funipuncture in fetuses with single umbilical arteries. Obstet Gynecol 2000; 95:557.
  54. Abdel-Fattah SA, Bartha JL, Kyle PM, et al. Safety of fetal blood sampling by cordocentesis in fetuses with single umbilical arteries. Prenat Diagn 2004; 24:605.
  55. Wiegand S, McKenna DS, Croom C, et al. Serial sonographic growth assessment in pregnancies complicated by an isolated single umbilical artery. Am J Perinatol 2008; 25:149.