Severe tortuous intra-abdominal segment of isolated single umbilical artery by three-dimensional high-definition flow imaging

The authors report a tortuous intra-abdominal segment of isolated single umbilical artery (SUA) that proved to be an omega-shaped variant by three-dimensional high-definition-flow (3D-HD-flow) imaging. A 28-year-old woman was referred to the present center for detailed fetal echocardiography examination after finding SUA during routine two-dimensional ultrasound examination at 24(+3) weeks' gestation. 3D-HD-flow demonstrated a severely tortuous and dilated intra-abdominal segment of SUA mimicking omega-shaped variant. Postnatal abdominal ultrasound and cardiac examination were unremarkable. This case suggests that the omega-shaped variant of SUA is probably a normal variant when unassociated with other structural anomalies. When a locally dilated umbilical artery is detected during routine 2D ultrasound, the authors recommend using 3D color Doppler imaging to more precisely determine the course of the umbilical artery.