Angiodysplasia

Angiodysplasia is a bleeding disorder caused by one or more (and often numerous) malformations of the blood vessels of the digestive tract. It's often difficult to diagnose as it presents as anemia, and there is no obvious blood in the stool. In addition, even when the stool is dark (indicating the possibility of bleeding), the bleeding can be intermittent and the patient can test negative for occult blood in the stool.
Traditionally, the condition was diagnosed with endoscopy. However, this was usually unreliable as the lesions were often difficult to find, particularly if they were few in number. As such, the pill camera is usually used when angiodysplasia is suspected.
It is believed angiodysplasia is quite common, but usually presents with no overt symptoms and usually has no complications. However, complications are worse in patients, who have any type of coagulopathy.
Treatment usually starts with a transfusion to stabilize the anemia. If the lesions are few in number, they can usually be treated by cauterization guided by an endoscope. However, when the lesions are widespread, medication can be used to stop the bleeding. Furthermore, if this course of treatment is ineffective, surgery is the treatment of last resort.
Angiodysplasia at Wikipedia