Angiodysplasia of the Colon Workup
- Author: Hussein Al-Hamid, MD; Chief Editor: BS Anand, MD more...
The best workup approach depends on many factors, including whether the bleeding is occult or overt, the presence of laboratory or clinical signs of severe bleeding, the patient’s age, and the presence of other comorbidities.
The workup usually starts with endoscopy (colonoscopy, with or without upper endoscopy, and wireless video capsule endoscopy). Angiography (usually preceded by a bleeding scan to guide angiography), deep small bowel enteroscopy, or even intraoperative enteroscopy might be warranted if the bleeding is massive, obscure, and ongoing.
The following laboratory tests are used in the evaluation of patients with suspected angiodysplasia of the colon:
Complete blood cell (CBC) count: Approximately 10% of patients who bleed from angiodysplasia present with anemia.
Serum iron level: Iron deficiency is found in 10% of patients with bleeding angiodysplasia.
Stool for occult blood: As many as 15% of patients with bleeding angiodysplasia will be intermittently positive for occult blood.
Selective mesenteric angiography is a useful diagnostic technique for angiodysplasias, especially in patients with massive bleeding in whom a colonoscopic diagnosis is difficult.
The sensitivity of angiography ranges from 58% to 86%. Detection of bleeding depends on the rate of bleeding (as low as 0.5 mL/min), technique, and timing of angiography in relation to the period of bleeding.
The most frequent and earliest angiographic sign is a densely opacified, dilated, and slowly emptying draining vein within the intestinal wall. This vein is detected during the venous phase of the study and is present in more than 90% of angiodysplastic lesions.
As the lesion progresses, a vascular tuft may become apparent during the arterial phase of the study. This is observed in as many as 70-80% of patients with angiodysplasia. It represents an extension of the dilation process to the mucosal venules.
The latest sign, an early-filling vein, may be observed in the arterial phase, indicating a more developed arteriovenous communication through the angiodysplastic lesion. It is observed in only 60-70% of cases of angiodysplasia.
The above 3 angiographic signs correspond to the development of ectatic changes in vascular lesions. Their prevalence has been recorded less systematically in other parts of the intestinal tract. However, the interpreter must consider all clinical information, because these angiographic findings may be observed in other disorders, such as malignancy
Demonstration of extravasation of contrast dye in the bowel lumen from angiodysplastic lesions is definite evidence of bleeding; however, this is observed in only 6-20% of patients. This low percentage is attributed to the episodic nature of the bleeding lesions.
Angiography of resected specimens has been used to confirm appropriate resection when preoperative studies are equivocal or unsatisfactory. An intraluminal formalin fixation technique on the resected specimen, followed by mucosal dissection, has also been used for documenting correct resection. Vasopressin infusion during angiography can arrest bleeding, but potential complications of vasopressin include bowel infarction, arterial vasospasm, and lower extremity ischemia.
Small bowel angiodysplasia accounts for 30-40% of cases of obscure GI bleeding and is associated with significant morbidity and mortality. Small bowel capsule endoscopy (SBCE) is a significant advance on earlier diagnostic techniques. Lymphangiectasia are seen in about half of those with angiodysplasia, in 19% of those with obscure GI bleeding without angiodysplasia, and in 14% of those without GI bleeding. Lymphangiectasia are strongly associated with the presence of small intestinal angiodysplasia and may represent a useful clinical marker for this condition.
When endoscopy is not available, angiography is a useful diagnostic tool in cases with massive GI bleeding such as angiodysplasia and varicosis. Angiodysplasia and varicosis have distinguishable characteristic features on angiography, such as the presence of a nidus, visible late-draining veins, and the typical vascular tuft. Histological examination may reveal that the lesion is an angiodysplasia and not varicosis.
Nuclear imaging studies
Radionuclide scanning using technetium-99m (99m Tc)–labeled red blood cells or99m Tc sulfur colloid is helpful in detecting and localizing active bleeding from angiodysplasia. Scanning can detect bleeding with rates as low as 0.1 mL/min. The intermittent bleeding nature of angiodysplasia has limited the utility of radionuclide studies in this disorder.
Red blood cells that are labeled with technetium have a long half-life in the intravascular compartment and are especially useful in patients with intermittent hemorrhage. The usefulness of technetium-labeled red blood cells is attributed to the ability to detect bleeding during the 12 or so hours after a single injection of radiolabeled cells.
The reticuloendothelial system rapidly clears99m Tc sulfur colloid.99m Tc sulfur colloid has a half-life of only 3 minutes; hence, it is helpful only in patients with active bleeding. The extravasated labeled sulfur colloid easily demonstrates the site of bleeding in the absence of confusing background activity in the circulation, although uptake into the liver and spleen restricts the image area.
Nuclear scans lack the specificity of an angiogram in differentiating the nature of bleeding lesions, despite the fact that they are noninvasive and relatively easy to perform. Nuclear scans have proven more useful as an adjunct to angiography by localizing and confirming the presence of bleeding, minimizing the number of angiograms that do not yield meaningful diagnostic information, and allowing rapid selection of the artery to be injected by angiography. Confirm positive findings from a radionuclide study by colonoscopy or angiography if surgical resection is contemplated (see image below).
Other imaging studies
Helical computed tomography (CT) angiography can detect extravasation from angiodysplasia and is potentially an important noninvasive test in patients with obscure bleeding sites.
Capsule endoscopy has been reported to detect cecal angiodysplasias in selected cases. Capsule endoscopy is particularly useful to demonstrate small intestinal lesions, but its role as a diagnostic test for the colon is still experimental.
Double-balloon endoscopy is useful to detect small bowel lesions, and retrograde double-balloon endoscopy may allow for careful inspection of the cecum and ileocecal valve.[51, 52]
It is recommended not to use air contrast barium enema during acute GI bleeding. Air contrast barium enemas can help exclude other causes of chronic colonic bleeding; however, they are not useful in detecting angiodysplasia, because the lesions are small and usually do not distort the colonic mucosa. In addition, barium enema can obscure other diagnostic studies.
Endoscopy is the most common method of diagnosing angiodysplasia in both the upper and lower GI tract.
Upper endoscopy is used to establish a diagnosis of gastric and duodenal angiodysplasia. Celiac artery and superior mesenteric artery arteriograms frequently fail to demonstrate these lesions, although large lesions with well-formed and enlarged draining veins have been reported in the gastric antrum. Angiography can demonstrate lesions in the more distal small intestine, a region less accessible to endoscopic evaluation. Push enteroscopy has proven to be a successful method of identifying angiodysplasia of the proximal small intestine in patients with obscure bleeding. Other methods of visually evaluating the small bowel include capsule endoscopy and deep or balloon enteroscopy, which are currently used in clinical practice.
The endoscopic appearance of gastric lesions typically has been described as discrete, flat, or slightly raised (2-10 mm) and bright red. These lesions have fernlike margins or stellate configurations. Proximal small intestinal lesions are the size of a pinpoint, with a similar gross appearance. A surrounding pale rim or halo also characterizes upper tract lesions.
Angiography or colonoscopy
Either angiography or colonoscopy may be used to detect colonic lesions. Because colonoscopy is a principal method in the evaluation of GI bleeding, the diagnosis of these lesions often results from colonoscopic examination.
Comparative studies using selective angiography and colonoscopy indicate that the sensitivity of colonoscopy exceeds 80% when the lesions are located in the area examined by colonoscopy. Most angiodysplastic lesions are located in the right colon, thus, the entire colon must be examined. Angiography has the advantage of detecting additional angiodysplastic lesions not depicted by colonoscopy. In a series by Emanuel et al, 17% of subjects were found to have concomitant colonic and extracolonic angiodysplasia when studied by triple-vessel angiography. Angiography and colonoscopy can play important complementary roles.
Skibba et al first described the colonoscopic appearance of angiodysplasia in 1976. Angiodysplastic lesions are often described as discrete and small, with scalloped or frondlike edges and a visible draining vein. They can be flat or slightly raised and can be hidden within the mucosal folds. Although angiodysplasia may be detected anywhere in the colon, a strong propensity exists for the cecum and ascending colon.
Angiodysplastic lesions encountered as incidental findings are generally small lesions with pale coloration compared with lesions with a recent hemorrhage, which are described as extremely bright with elevated centers.
The endoscopic appearance of angiodysplasia can be confused with the ectasias associated with systemic diseases, such as hereditary hemorrhagic telangiectasia (HHT), Turner syndrome, Ehlers-Danlos syndrome, blue rubber web nevus syndrome, the CREST variant syndrome (calcinosis, Raynaud phenomenon, esophageal hypomotility, sclerodactyly, and telangiectasia) of scleroderma, gastric antral vascular ectasia (GAVE), portal hypertensive colopathy, and radiation-induced injury. The lack of systemic manifestations distinguishes angiodysplasia from these syndromes.
In addition, the endoscopic appearance of angiodysplasia may be difficult to discern from spider angiomata, radiation injury, ulcerative colitis (see image below), Crohn disease (see image below), ischemic colitis, and suction artifacts.
Evaluation of a patient who may have angiodysplasia requires that the colonoscope be inserted carefully, with minimal use of suction, and that the mucosa should be examined more carefully as the instrument is advanced than during withdrawal. Obtaining a biopsy of suspicious lesions may be necessary if classic features are not present.
Because blood pressure and volume influence the colonoscopic appearance of vascular lesions, angiodysplasia may not be evident in patients who have bled recently. Accurate evaluation of the colon may not be possible until after effective fluid resuscitation and blood transfusions.
Some studies have noted that administering meperidine may diminish the prominence of some vascular abnormalities, and some researchers have advocated reversal by naloxone to aid in the accurate detection of these lesions.
In persons with obscure GI bleeding, the overall diagnostic yield of video capsule endoscopy was 61%. Angiodysplasia was diagnosed in (54%) patients older than 65 years, whereas mucosal breaks, (such as erosions or ulcers), accounted for over a quarter of finding in persons aged 65 years or younger.
The underlying etiologies for lower GI bleeding included diverticular disease (59%), angiodysplasia (19%), ulcers (19%), and malignancy (3%). The use of superselective mesenteric embolization for the treatment of lower GI bleeding is technically successful in 97%, whereas 3% develop postembolization ischemia.
Lesions outside the small bowel as possible sources of obscure GI bleeding are found in about half of patients; a definite source of bleeding outside the small bowel (SB) was detected in about a quarter. Therefore, repeat esophagogastroduodenoscopy (EGD) and ileocolonoscopy should be taken into consideration before video capsule endoscopy or deep enteroscopy.
Despite standard endoscopic diagnostic evaluations, as many as 30% of patients with iron deficiency anemia (IDA) remain without a definitive diagnosis.
In one study, capsule endoscopy (CE) in persons with unexplained IDA revealed angiodysplasias in 51 patients; jejunal and/or ileal micro-ulcerations in 12 patients; tumors/polyps in 9 patients; erosive gastritis in 4 patients; Crohn disease in 5 patients; jejunal villous atrophy in 5 patients; a solitary ileal ulcer in 1 patient, and active bleeding in the last 4 patients. Follow-up data were available for 80 of 91 patients (87.9%). In a third of patients with angiodysplasias, IDA spontaneously resolved without any treatment; about one fifth of the patients required iron supplementation, and one fifth healed after lanreotide administration. APC was performed in one fifth of patients, and the remainder required regular blood transfusions.
Angiodysplasia is the most common reason (50%) for obscure GI bleeding, as shown on CE. The pooled completion rate of CE was 84%. The pooled retention rates were approximately 2%.
Angiodysplasia can be detected infrequently by visual inspection of the serosal side of the bowel during laparotomy. Richardson et al made a correct diagnosis of angiodysplasia during surgical exploration in only 1 of 39 cases (2.6%). The remaining patients were diagnosed by angiography or colonoscopy. Fourteen of these individuals had undergone 21 nondiagnostic surgeries before their evaluation.
Intraoperative enteroscopy can help in localization of distal small bowel lesions. In addition, an angiographic catheter can be placed before surgery into the appropriate feeding vessel supplying the angiodysplastic lesion. The surgeon then can identify the catheter during surgery and explore and resect the appropriate small bowel segment.
Angiodysplasia (9 mm), GI stromal tumor (15 mm), and AVM may be clearly detected by virtual enteroscopy.
CT enteroclysis is a noninvasive method and useful approach in the diagnosis of small intestinal diseases.
Wireless capsule endoscopy (CE) was first FDA approved to evaluate small intestinal disease in 2001. It can be performed in an ambulatory setting. The most common indication is evaluating obscure GI bleed (OGIB), whether overt or occult.
Deep enteroscopy procedures, whether double-balloon enteroscopy (DBE), single-balloon enteroscopy (SBE), or spiral enteroscopy (SE), are newer, advanced endoscopic procedures that have the ability to access the entire small bowel via both the anterograde and retrograde approach. They have the advantage of being diagnostic and therapeutic in many small intestinal diseases, including angiodysplasia.
A multicenter prospective trial that compared DBE to SBE in 100 patients revealed that DBE had a higher therapeutic yield and total enteroscopy yield with a 3-fold higher rate of complete enteroscopy compared to SBE.[62, 63] A prospective randomized trial of 241 patients that compared DBE and SE showed that both were comparable in terms of diagnostic yield, therapeutic yield, procedure time, and maximal insertion depth. Another study that compared SE and SBE in 92 patients showed that maximal insertion depth was significantly higher for SE than for SBE; however, diagnostic yield and procedure time were comparable.
A likely cause for obscure GI bleeding was found in the small bowel during balloon-assisted enteroscopy (BAE); angiodysplasia or AVM were found in 70% of patients, ulcerative lesions was found in 12% of patients, tumors were found in 5% of patients, and other findings were found in 13% of patients. In 76% of patients with findings at BAE, endoscopic treatment was administered in 71%, but anemia also improved spontaneously in 63% with normal findings during BAE.
To evaluate the diagnostic value of DBE for obscure GI bleeding, one study showed that bleeding was most commonly associated with small bowel tumor (28%), angiodysplasia (19%), and Crohn disease (11%).
The overall complication rate DBE is about 0.9, with no significant difference between age groups. Elderly patients were more likely to have angiectasias (39% vs 23%; P = .01), and were more likely to require endoscopic therapy during DBE (46.8% vs 29.2%; P = .01).
One of the main indications for DBE is suspected small-bowel bleeding (SSBB). The most common finding may be angiodysplasia. The rate of rebleeding in patients who had undergone therapeutic interventions (20%) was similar to that in patients who did not (18%).
The combination of double-balloon enteroscopy (DBE) and laparoscopically assisted bowel surgery (LABS) represents a useful therapeutic method for obscure GI bleeding caused by small bleeding neoplasms or vascular lesions.
No consensus has been reached on the relative accuracy of CE versus DBE to investigate obscure GI bleeding. The positive findings for each type of lesion were similar for angiodysplasia (CE, 65% and DBE, 61%), ulcers (CE, 20% and DBE, 19%), and mass (CE, 10% and DBE, 9%). CE was superior to DBE in detecting bleeding lesions (CE, 43% and DBE, 15%, P=0.0004). DBE provides the advantage of therapeutic intervention by argon plasma coagulation, clipping, polypectomy, tattooing, and biopsies. CE and DBE are complementary, and both evaluate obscure GI bleeding more fully than either modality alone. Three meta-analyses that compared the diagnostic yield of DBE to CE in patients with OGIB showed comparable results. CE is also superior to DBE in being noninvasive and having higher rates of achieving total small intestinal examination.
CE and magnetic resonance enterography (MRE) are complementary methods which, when used in conjunction, may better characterize suspected small bowel disease.
Endoscopic forceps biopsy has revealed characteristic histopathologic features of angiodysplasia in only 31-60% of specimens. Endoscopic mucosal biopsies for the purposes of diagnosis are generally not recommended because of the low diagnostic yield and the risk of provoking hemorrhage.
However, the histologic diagnosis of angiodysplasia is difficult. Acquired lesions such as angiodysplasias must be differentiated from vascular tumors, lesions associated with congenital or systemic disease, or radiation damage.
Angiodysplasias typically are irregularly shaped clusters of ectatic small arteries, small veins, and their capillary connections. They are more often multiple than single. Microscopically, angiodysplastic lesions are dilated, distorted, thin-walled vessels. The amount of smooth muscle in the vessel wall is variable. The vessel wall can become so thinned that it appears to be composed only of endothelium.
Markedly dilated submucosal vasculature is the most consistent abnormality and the earliest change identified. More advanced lesions involve the mucosa. Because the major portion of the lesion is often submucosal, endoscopic mucosal biopsies are often not diagnostic. Characteristic histopathologic findings of angiodysplasia are identified only in 31-60% of endoscopically obtained biopsies.
In addition, routine pathologic examination usually discovers less than one third of lesions. Injecting the colonic vasculature with silicone rubber and clearing the specimen can be used to identify almost all lesions. In this process, the rubber compound is injected through a catheter placed in one or more of the arteries supplying the colon, after which the specimen is refrigerated for 24 hours to allow the silicone to polymerize. Specimens are then dehydrated in increasing concentrations of ethyl alcohol and cleared with methyl salicylate. The result is a transparent specimen with a filled vascular bed, which is studied through a dissecting microscope using direct light as well as transillumination.
Overlapping features and poor endoscopic-histologic correlation make the distinction challenging between portal hypertensive gastropathy (PHG) and GAVE. Thrombi were revealed in 100% of histologically confirmed cases of GAVE and in 60% of cases suspected of GAVE on endoscopy alone; control biopsies were negative. Mucosal microvessel density (MVD) was significantly higher in GAVE than PHG.
Comparative histological and electron microscopic study of arteriovenous and venous angiodysplasias revealed specific features of their structure, presumably reflecting differences in their morphogenesis. Specific ultrastructural characteristics of angiodysplasias are modified shape of endotheliocytes, impaired structure of the basal membrane, and reduced count of pericytes.
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