Case report:

A 35-year-old women (G4P1Ab2) was referred to our fetal medical unit for routine prenatal scanning at 21 weeks 5 days. With relevant history of homozygous MTHFR mutation (methylenetetrahydrofolate reductase), she was receiving Enoxaparin treatment.

At 21 weeks 5 days, we found an isolated persistent right umbilical vein.

With the follow-up ultrasounds at 26 weeks and 37 weeks, we suspected it was associated with inferior vena cava interruption with continuity of the venous flow via Azygos vein. The baby was born at term and was doing well.

Image 1: At 21 weeks, persistent right umbilical vein ( arrow) next to gallbladder (*)

Image 2: Routine transverse view of the abdomen and thorax showing a vessel posterior and to the right of the aorta (Azygos vein).

Images 4, 5: 26 weeks-Persistent right umbilical vein and again a vessel posterior and to the right of the aorta (Azygos vein).

Images 6, 7: 37 weeks, four-chamber and five-chamber view with the aorta and Azygos vein

Images 8-11: Persistent right umbilical vein and Inferior vena cava interruption with continuity of the flow via Azygos vein on grayscale and color Doppler

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