Portal vein thrombosis associated with rectal bleeding: non-invasive diagnosis and follow up by ultrasound.

A 65 year old woman presented with a sudden onset of abdominal pain and bright rectal bleeding. Shortly after admission a diagnosis of partial portal vein thrombosis was made by ultrasonography. This thrombosis appeared to be the first sign of a previously unsuspected hypercoagulable state due to polycythaemia rubra vera. Ultrasound proved useful in confirming complete resolution of the portal system thrombosis in response to conservative therapy.