ACCESSORY VESSELS OF THE UMBILICAL CORD  

 

4-vessel umbilical cord

2 veins + 2 arteries

Four-vessels cords result from the persistence of the right umbilical vein. Some reports suggest an increase in congenital anomalies (such as ectopia cordis, atrial septal defect, symmetrical bifid liver, cleft lip and palate, arteriovenous fistulas of the placenta) (3,4), while others do not (5,6).

1 vein + 3 arteries

Another common cause (up to 5% of cords) for a fourth vessel is the persistence of small vitelline arteries. These rarely exceed 0.5 mm in diameter (7). These extra vessels follow the normal twisting of the main umbilical arteries. Actually most of those vessels are actually paired or partially doubled, so that the cord contains on some length 4 arteries. Usually these vessels run for the whole length of the cord. No increase in congenital anomaly was observed.

 

1 vein + 2 arteries + 1 duct

Allantoic (2/3) or omphalomesenteric (1/3) duct remnant are not true vessels, however the ultrasound appearance makes it difficult to distinguish since flow in such small vessels may not always be detected with either pulsed or color Doppler. At pathology, vestigial remnants with flat epithelium originate from the allantoic duct, while remnants with cuboidal or columnar epithelium originate from the omphalomesenteric duct. The allantoic remnants persist until term while omphalomesenteric duct remnants disappear by mid-gestation (7).

5 or more vessels in the cord

These are the numerous variations associated with conjoined twining.

Unequal numbers of vessels in different portions of the cord

Partial division of the primordial umbilical artery
Occasionally the original primordial umbilical artery fails to divide longitudinally in two umbilical arteries. The division starts at the placental end and extends towards the embryo. These cords will thus present with 3-vessel on the placental end but 2 on the fetal end.
A rare form of unequal number occurs in minimally conjoined twins or in monoamniotic twins that only share part of the cord. Those cords are forked and may have either a single umbilical artery for each twin but may even have normal 3-vessel cords for each twin reduced to a 2-vessel cord at implantation.

False positive multiple cord vessels

 

 

Normal three vessel coiled cord which gives the impression of accessory vessels due to exquisite visualization

 

An accessory fourth vessel of the umbilical cord was found to be present in 5% of umbilical cords examined by Meyer et.al.(1).
The fourth vessel structure was considered a remnant of either the allantois, vitelline duct or right umbilical vein.
No antenatal deaths or fetal malformations were present.

Nadkarni (2) found one or two supernumerary small vessels in five cases (2%). These vessels were identified as arteries on light and electronmicroscope.
All infants were normal.

False positive extra cord vessels

The tortuosity of the umbilical artery resulted in us cutting through a plane that images only parts of the vessel giving the impression that there are five vessels in the cord. A more longitudinal view (on the right) confirmed a three vessel cord/


 

REFERENCES
  1. Meyer WW, Lind J, Moinian M. An accessory fourth vessel of the umbilical cord. Am J Obstet Gynecol 1969;105:1063.
  2. Nadkarni BB. Congenital abnormalities of the human umbilical cord and their clinical significance: A light and electronmiscrope study. Ind J Med Res 1969;57:1018.
  3. Painter D, Russell P. Four-vessel umbilical cord associated with multiple congenital anomalies. Obstet Gynecol 1977 Oct;50(4):505-507
  4. Chiappa E, Viora E, Botta G, Abbruzzese PA, Ciriotti G, Campogrande M Arteriovenous fistulas of the placenta in a singleton fetus with large atrial septal defect and anomalous connection of the umbilical veins. Ultrasound Obstet Gynecol 1998 Aug;12(2):132-135
  5. Schimmel MS, Eidelman AI Supernumerary umbilical vein resulting in a four-vessel umbilical cord. Am J Perinatol 1998 May;15(5):299-301
  6. Rodriguez MA Four-vessel umbilical cord without congenital abnormalities. South Med J 1984 Apr;77(4):539
  7. Meyer WW, Lind J, Moinian M An accessory fourth vessel of the umbilical cord. A preliminary study. Am J Obstet Gynecol. 1969 Dec 1;105(7):1063-1068