Reviewed by Medical Advisory Board
The umbilical cord is the tube-like structure that
connects the baby from the abdomen to the placenta (and mother). The umbilical cord usually contains three blood vessels ;
one
vein and two arteries ( a 3 vessel cord) . The vein carries blood rich in
oxygen and nutrients from the placenta to the fetus. The arteries
carry oxygen poor blood and waste products from the fetus to the placenta.
Occasionally, one artery wastes away or fails to develop leaving only a
single umbilical artery (a two vessel umbilical cord). A single umbilical
artery (SUA) is seen in 0.2% to 1% of pregnancies [1-3] at delivery, but
may be detected in up to 6% of pregnancies during the first trimester [4].
SUA is reported to be more common in in mothers with pregestational diabetes, twin pregnancies, and in placentas where
the umbilical cord is at the edge of the placenta [3,5].
Although SUA may occur alone (isolated) , in some cases SUA may be associated
with a collection of other findings that suggest a specific disorder
(syndrome). When SUA is found a detailed ultrasound will usually be done to search
for gastrointestinal malformations, heart defects , and abnormalities
of the kidneys, brain, and bones [4-7]. If additional abnormalities are
found , there may be as high as a 50% chance that the baby has a chromosomal
abnormality in particular trisomy 13 or trisomy 18 [5-11]
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For fetuses with isolated SUA, the Society for Maternal-Fetal Medicine (SMFM) recommends no additional evaluation for
missing or extra
chromosome
material (aneuploidy) regardless of whether results of previous screening
for aneuplody were low risk or testing was declined. Because
isolated SUA has been associated in some studies with an increased
risk of stillbirth and
fetal growth restriction
, a third trimester ultrasound to evaluate
for fetal growth
and antenatal testing beginning at 36 0/7 weeks are recommended [13]. Pediatric providers should be informed of the
prenatal
findings at the time of delivery , since additional findings in some syndromes may go
undetected until after delivery
[6]
.
By Mark Curran, MD FACOG Updated 10/16/2021
REFERENCES
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2. Bryan EM, Kohler HG.The missing umbilical artery. I. Prospective study based on a maternity unit.Arch Dis Child. 1974 Nov;49(11):844-52. PMID: 4474841
3. Heifetz SA.Single umbilical artery. A statistical analysis of 237 autopsy cases and review of the literature.Perspect Pediatr Pathol. 1984 Winter;8(4):345-78.PMID: 6514541
4. Rembouskos G, et al. Single umbilical artery at 11-14 weeks' gestation: relation to chromosomal defects. Ultrasound Obstet Gynecol. 2003 Dec;22(6):567-70.
PMID: 14689527.
5. Thummala MR, Raju TN, Langenberg P. Isolated single umbilical artery anomaly and the risk for congenital malformations: a meta-analysis. J Pediatr Surg. 1998 Apr;33(4):580-5. doi: 10.1016/s0022-3468(98)90320-7. PMID: 9574755.
6. Chow JS, Benson CB, Doubilet PM. Frequency and nature of structural anomalies in fetuses with single umbilical arteries. J Ultrasound Med. 1998 Dec;17(12):765-8.PMID: 9849950
7. Lilja M.Infants with single umbilical artery studied in a national registry. 2: Survival and malformations in infants with single umbilical artery. Paediatr Perinat Epidemiol. 1992 Oct;6(4):416-22. PMID: 1475216
8. Ebbing C, Kessler J, Moster D, Rasmussen S. Single umbilical artery and risk of congenital malformation: population-based study in Norway. Ultrasound Obstet Gynecol. 2020 Apr;55(4):510-515. doi: 10.1002/uog.20359. PMID: 31132166.
9. Saller DN Jr, Keene CL, Sun CC, Schwartz S. The association of single umbilical artery with cytogenetically abnormal pregnancies. Am J Obstet Gynecol. 1990 Sep;163(3):922-5.
PMID: 2403169
10. Nyberg DA, Mahony BS, Luthy D, Kapur R.Single umbilical artery. Prenatal detection of concurrent anomalies. J Ultrasound Med. 1991 May;10(5):247-53.PMID: 2051544
11. Catanzarite VA, aet al., Prenatal diagnosis of the two-vessel cord: implications for patient counselling and obstetric management.Ultrasound Obstet Gynecol. 1995 Feb;5(2):98-105. PMID: 7632225
12. Ebbing C, Kessler J, Moster D, Rasmussen S. Isolated single umbilical artery and the risk of adverse perinatal outcome and third stage of labor complications: A population-based study. Acta Obstet Gynecol Scand. 2020 Mar;99(3):374-380. doi: 10.1111/aogs.13747. Epub 2019 Nov 18. PMID: 31603530.
13. Society for Maternal-Fetal Medicine (SMFM). Electronic address: pubs@smfm.org, Prabhu M, Kuller JA, Biggio JR. Society for Maternal-Fetal Medicine Consult Series #57: Evaluation and management of isolated soft ultrasound markers for aneuploidy in the second trimester:
Am J Obstet Gynecol. 2021 Oct;225(4):B2-B15.PMID: 34171388.
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