* Fetal medicine unit, Cairo University, Egypt;
** Radiology department, Kasr Alainy teaching hospitals, Cairo University, Egypt.

Case Report

A 33 year-old (G2P1) woman with unremarkable history came to our unit for a routine anatomy scan at 18 weeks of gestational age. Abnormal course of what presumably seemed to be the umbilical vein has been observed in the axial section. It did not follow the normal intrahepatic course but instead it coursed downwards to join the infra hepatic circulation. Although the umbilical vein was of normal caliber from its entry through the umbilicus and up to the end of its straight course; a mild fusiform dilatation (ectasia) was observed near its connection to the infrahepatic circulation. The position of the vein in between the left sided stomach and the right sided gallbladder excluded the possibility of a persistent right umbilical vein. 

In sagittal views, a downward course of the infrahepatic connection was confirmed.  The rest of the anatomy scan was unremarkable and especially the two umbilical arteries were visualized around the urinary bladder and in cross-sectional images of the umbilical cord. 

A follow-up was recommended and the patient attended at 24 weeks of gestation at which an ectasia of the connecting vein was established, measuring 9.7mm. It remained as such untill the end of pregnancy. The ductus venosus was not seen (ductal agenesis type III).

Doppler assessment of the ectatic segment revealed absence of intraluminal filling defects with unidirectional monophasic waveform pattern. Follow up of the fetus did not reveal thrombosis in the ectasia. Cardiac assessment in follow-up studies was unremarkable. 

A healthy male baby was born at 37 weeks gestation by C section due to an obstetric indication with uneventful postnatal course. The ectasia was confirmed by postnatal sonography and follow up did not show any thrombotic events.

Images 1 and 2; videos 1 and 2: axial and sagittal gray-scale views showing the downward course of the connecting vein below the right sided gallbladder to join the infra hepatic circulation.

Image 3; videos 3 and 4: axial gray scale view showing the ectasia and its relation to the gall bladder.

Images 4-6; videos 5-8: axial color Doppler views showing the absence of intra luminal filling defects of the ectasia. The normal anatomical configuration of the portal venous system is evident.

Image 7: unidirectional monophasic waveform in the ectasia was seen as well as the typical waveform pattern of the ductus venosus flow.

Images 8 and 9:axial and coronal color Doppler showing paired umbilical arteries around the urinary bladder and the connection of the ectasia to the portal system

Video 9: color Doppler on axial planes starting from the level of the vitelline and extending to its connection to the portal system then demonstrating the portal veins.

Discussion

The umbilical vein normally connects to the intrahepatic portal system at the portal sinus which extends from the origin of the inferior left portal vein to the origin of the right portal vein¹. The umbilical vein should not connect to the extrahepatic portal system and if this occurs, this is classified as group IV umbilical vein anomaly recently described by many authors as a ductal agenesis type 3 and persistent vitelline vein². This is different from the persistent right umbilical vein in which the gallbladder is located between the umbilical vein and the stomach³. The most important sonographic clues for this diagnosis which has been reported rarely in the prenatal literature include the characteristic downward course of the vein and its connection to the extra hepatic portal system⁴. As typically reported by others; an early detection supports the diagnosis of ectasia of the vein over the umbilical vein varix. A single umbilical artery was encountered in the case reported by Kivilevitch and Achiron raising their suspicion about simultaneous agenesis of both umbilical arteries and veins with persistence of the vitelline vein as a replacement⁴; however our case has two umbilical arteries making this suspicion unlikely. To our knowledge, this is the earliest case report of such rare anomaly (18 weeks) ^{4, 5}.

References:   1- Mavrides G, Moscoso G, Carvalho JS, Campbell S, Thilaganathan B: The anatomy of the umbilical, portal and hepatic venous systems in the human fetus at 14-19 weeks of gestation. Ultrasound Obstet Gynecol. 2001; 18(6): 598-604.

2- Jaima S, Nalluri HB: Abnormal continuation of umbilical vein into extra-hepatic portal vein: Report of three cases. Congenital Anomalies 2013; 53: 170-175.

3- Wolman I, Gull I, Fait G, Amster R, Kupferminc MJ, Lessing JB, Jaffa AJ: Persistent right umbilical vein : incidence and significance. Ultrasound Obstet Gynecol 2002; 10:562-564.

4- Kivilevitch Z, Achiron R: Fetal extrahepatic vitelline vein aneurysm mimicking an umbilical vein varix. J Ultrasound Med 2010; 29: 1651-1656.

5- Héry G, Quarello E, Gorincour G, Franchi S, Gauthier F, de Lagausie P. Extrahepatic vitelline vein aneurysm: prenatal diagnosis and follow up. Journal of pediatric surgery. 2013 Aug 31; 48(8):e1-4.