Can you guess the cause of the patient’s bleed?

A 75 year old woman comes in with an acute gastrointestinal bleed and a history of recurrent nose bleeds. Based on these pictures, do you know the cause? (scroll down for the answer)

This is a patient with hereditary hemorrhagic telangiectasia (Osler-Weber-Rendu syndrome) and both bleeds have been caused by telangiectasia throughout her upper airways and GI tract. In some cases GI bleeds can be caused by arterial-vascular malformations (AVM’s). Of note, the patient has issues with hepatic encephalopathy due to AVM’s in the liver. Sometimes, these patients get hypoxia. Any guess as to why?