Arteriovenous malformations (AVMs) are generally located in the cecum or ascending colon. If they are not actively bleeding, they will appear as a spider-like network of vessels, as seen here. Their size can be variable, from a few millimeters to a centimeter or more in size
In the case of smaller AVMs, the spider-like pattern may not be as evident, as in this 5 mm size AVM.
Bleeding from an AVM is usually seen as oozing of fresh blood, as seen here, as opposed to spurting or pulsating bleeding, as would be expected from an arterial source of bleeding. Often, as the lesion bleeds, the spider-like collection of vessels is depleted of blood and the vascular network is not seen, even if the blood is washed away.
Thermal therapy, in this instance applied using a bipolar coagulating device, can stop the bleeding and destroy the AVM. The resultant eschar seen here will eventually be replaced by a mild white scar.
An alternative method of treatment is to use an argon plasma coagulator to obliterate the AVM, thereby controlling bleeding, as seen here. As in the case of bipolar electrocoagulation therapy, the goal of treatment is to cauterize the AVM, as was achieved here. The resulting appearance is similar to that in the bipolar coagulation case above (5-4).
Vascular lesions, similar in appearance to right-sided colon AVMs, result from radiation therapy used to treat prostate and cervical cancer. Generally, there are many of these vascular lesions located within the distal 5–10 cm of the rectum. These can frequently be the result of mild hematochiezia in patients with prior radiation therapy. They usually do not require thermal therapy, as the bleeding caused by these vascular lesions is usually intermittent and not associated with blood loss significant enough to cause anemia.
The vascular lesions from radiation therapy are usually small, less than 1 cm in size. While they can have a spider-like appearance similar to AVMs, they often appear as ectatic blood vessels, as seen here and ...