HYPOPLASTIC UMBILICAL ARTERY  

A hypoplastic umbilical artery is an artery whose diameter is smaller than the contralateral artery by 1 mm, 30% or 50% depending on the various authors. The differences in diameter usually result in much dramatic difference of cross-section area where the hypoplastic umbilical artery is 2-3 times smaller than the contralateral artery.

-         Diagnosis is based on the visualization of discordant size between both umbilical arteries.

-         There are also discordant umbilical artery flow velocity waveforms.

-         Blood flow can be demonstrated within the hypoplastic vessel (this excludes an atrophic vessel).

-         Dolkart et.al. (12) reported six cases of discordant umbilical arteries in which the smaller artery measured up to 2mm in diameter less than the larger artery. Discordant umbilical artery waveforms were also present. Poor perinatal outcome was present in two cases (one had biliary atresia).

-         Sepulveda et.al (13) reported on two cases. Both fetuses had associated anomalies (urinary tract in one case and central nervous system in the other case).

-         Workers (12,14) have questioned whether hypoplastic umbilical artery represents a milder form of single umbilical artery.

 

     

 

 

Video clip of a hypoplastic umbilical artery

 

 

 


The resistance index of hypoplastic umbilical artery is also increased, but without pathological connotation, simply reflecting a greater resistance due to the small diameter.
trisomies.

Being aware of the normally increased resistance in the hypoplastic umbilical artery should be sufficient to not consider it a sign of placental disease.

ASSOCIATED ANOMALIES
  • Placental pathology .
  • Polyhydramnios.
  • Congenital heart disease.
  • Fetal growth restriction.
  • Stillbirth.

 

REFERENCES
  1.  Dolkart LA, Relmers FT, Kuonen CA. Discordant umbilical arteries: Ultrasonographic and doppler analysis. Obstet Gynecol 1992;79:59-63.
  2. Sepulveda W, Flack NJ, Bower s, Fisk NM. The value of color doppler ultrasound in the prenatal diagnosis of hypoplastic umbilical artery. Ultrasound Obstet Gynecol 1994;143-146.
  3. Nyberg DA, Mahony BS, Luthy D et.al. Single umbilical artery. Prenatal detection and concurrent anomalies. J Ultrasound Med 1991;10:247-253.