CLASSIFICATION OF SINGLE UMBILICAL ARTERY (1)

Type	Frequency	Origin of SUA	Umbilical Vein	Number of cord vessels	Associated Abnormalities
I	98%	Allantoic from left or right Iliac artery	Left	2 One artery One vein	CNS Lower Gut Acardia Short cord syndrome
II	1.5%	Vitelline from SMA	Left	2 One artery One vein	Severe malformation Sirenomelia Caudal regression Anal agenesis
III	Very rare	Vitelline or allantoic Iliac artery or SMA	Left and persistent right	3 One artery Two veins	TAPVD Renal agenesis Ipsilateral limb reduction Unicornuate uterus Hydranencephaly
IV	Very rare	Vitelline or allantoic Iliac artery or SMA	Right	2 One artery One vein	Embryos lost before prenatal or pathological assessment

REFERENCES

1. Blackburn W, Cooley W. Umbilical cord. In: Stevenson, Hall and Goodman (eds.). Human Malformations and related anomalies, vol II, pp.1275. New York: Oxford University Press.