Similar to colonoscopy, angiography can be both diagnostic and therapeutic in lower GI bleeding. It is particularly useful in patients with ongoing bleeding whose colons are unprepped and in those with severe bleeding, which would likely limit visualization during colonoscopy. Angiographic vasopressin infusion is not commonly used due to its high bleeding recurrence rate and complications [13]. Super-selective microcatheter embolization is usually performed for hemostasis using small 2.5–3 Fr microcatheters that are advanced through larger catheters and through which various embolic agents can be deployed, including microcoils, microparticles, and glue. Initial clinical success with this technique is achieved in over 95 % of patients, with a rebleeding rate of about 22 %. The major concern with angiographic intervention lies in its potential for serious adverse events in about 17 % of cases, including bowel ischemia and infarction, hematoma, thrombosis, and vascular dissection [14].

Surgical resection is the last resort for ongoing lower GI bleeding that is refractory to less invasive endoscopic and angiographic management, since it carries substantial morbidity and mortality, especially in emergent situations. Blind segmental resection is not recommended due to its high rate of recurrent bleeding, morbidity, and mortality. Segmental resection is preferred with lower rebleeding rates ranging from 0 to 14 %. Subtotal colectomy carries the lowest rebleeding rate (<5 %), but with higher morbidity than targeted segmental resection.

Multiple endoscopic options are available for treating a colonic diverticulum with active bleeding or stigmata of recent bleeding, including epinephrine injection, thermal coagulation, mechanical therapy, or a combination thereof [12]. Once a bleeding diverticulum is identified, the location should be marked with a submucosal injection of a tattooing agent to localize the bleeding area if subsequent endoscopic or surgical therapy becomes necessary. Alternatively, a clip can be placed next to the site to mark its location, although the clip is not meant to be served as a permanent endoscopic or fluoroscopic marker.

Epinephrine injection in four quadrants can control bleeding or close the mouth of the diverticulum by tamponade. A bleeding or non-bleeding visible vessel can be identified at the neck or at the dome of the diverticulum. Adherent clots can be removed using the cold snare guillotine technique (similar to the technique for upper GI bleeding), and any underlying lesion should be treated appropriately. TTS clips can be placed directly on the culprit vessel (Video 15.4) or used to close the entire diverticulum (Fig. 15.1) [16]. One study suggests that clip placement targeted at the vessel is more effective than closing the entire diverticulum in a “zipper” fashion [17]. If utilized, contact thermal therapy should be applied carefully, particularly in the dome of the diverticulum. The suggested treatment settings for bipolar coagulation are a power of 10–15 W and short 1–2 s pulse duration, with light to moderate probe-tissue contact pressure (Video 15.5). If clips or thermal therapy are not feasible due to difficult access, particularly in a narrowed, angulated sigmoid colon, EBL can be considered (Fig. 15.2). The band ligation cap is useful in this setting to facilitate access to the bleeding diverticulum. An area adjacent the bleeding diverticulum should be marked with a tattoo or clip to aid visual identification when an upper endoscope loaded with the banding device is subsequently introduced (Video 15.6).

At colonoscopy, an angiodysplasia has a characteristic appearance of a 2–10 mm, red, fern-like, flat lesion with ectatic vessels radiating from a central vessel. Poor bowel preparation and use of meperidine and other opiates, which transiently decrease mucosal blood flow, could potentially hinder the identification of angiodysplasias. If there is a history of guaiac-positive stool or iron deficiency anemia, angiodysplasias should be treated even if not actively bleeding. Angiodysplasias without evidence of GI bleeding should not be treated.

Bleeding angiodysplasias can be treated with a variety of thermal therapies [12]. Clips may not be effective for angiodysplasias and are not typically used. Contact thermal coagulation begins with the outer feeder vessels and progresses toward the central vessel, although the focus should be on the central vessel. However, APC is more popular than contact thermal methods, with a reported 77–83 % success rate (Fig. 15.3) [18]. Over-insufflation of the colon should be avoided before and during therapy as it can increase the risk of perforation due to thinning of the colon wall. For a very large angiodysplasia, injecting epinephrine near the center vessel can shrink the size of the lesion and decrease the amount of coagulation needed.

There is a potential role for medical treatment of angiodysplasias, particularly when numerous and diffuse, although most of the data are from studies of small bowel angiodysplasias. Octreotide administered subcutaneously in doses ranging from 100 μg to 500 μg two times a day may decrease the need for transfusions [19]. Thalidomide at a dose of 100 mg orally once a day may also decrease the rebleeding rate from angiodysplasias [20]. A randomized trial of estrogen-progesterone treatment for 1 year did not decrease the rebleeding rate from angiodysplasias, with higher morbidity and mortality [21, 22]. Hormone therapy may decrease bleeding from telangiectasias in patients with Osler-Weber-Rendu disease.