A 28-year-old pregnant woman with a very rare cause of jugular vein thrombosis.

During pregnancy, venous thrombosis of the distal extremities is not uncommon. However, thrombosis in the upper part of the body, such as jugular vein thrombosis, is rare. If underlying causes such as ovarian hyperstimulation syndrome (OHSS) or septic thrombophlebitis (Lemierre's syndrome) are excluded, a serous borderline ovary tumour (BOT) must be considered and MR imaging of the abdomen could be performed to find a primary tumour mass.