New Tools Advance Diagnosis of Obscure GI Bleeding
Elsevier Global Medical News
The driving force behind the American Gastroenterological Association's new technical review and medical position statement on obscure gastrointestinal bleeding was the advent of capsule endoscopy and double-balloon enteroscopy, according to the lead author of the review, Dr. Gottumukkala S. Raju.
Since 2000, when the last technical review on obscure GI bleeding was published, "technical advances in endoscopy have revolutionized the evaluation and management of patients with obscure GI bleeding," the position statement says.
At that time, "the technology consisted of esophagogastroduodenoscopy, colonoscopy, push enteroscopy, small bowel x-rays, angiograms, and some bleeding or Meckel's scans," said Dr. Raju, professor of medicine and director of endoscopy at the University of Texas Medical Branch, Galveston. Because of the limitations of these techniques for locating the origin of bleeding, many patients continued to return to the hospital, required multiple transfusions, and needed repeated evaluations at great cost, he said in an interview.
In the position statement and technical review, which appear in the November 2007 issue of Gastroenterology, obscure GI bleeding is defined as "bleeding from the GI tract that persists or recurs without an obvious etiology after esophagogastroduodenoscopy (EGD), colonoscopy, and radiologic evaluation of the small bowel such as small bowel follow-through or enteroclysis." Bleeding lesions "that are overlooked in the esophagus, stomach, and colon during initial work-up or lesions in the small intestine that are difficult to visualize with conventional endoscopy and radiologic imaging are responsible for the obscurity of the etiology of GI bleeding," the statement says.
Dr. Raju is also codirector of the Center for Endoscopic Research, Training, and Innovation (CERTAIN) at UTMB. His coauthors on the position statement and technical review are Dr. Lauren Gerson of Stanford (Calif.) University; Dr. Ananya Das of the Mayo Clinic, Scottsdale, Ariz.; and Dr. Blair Lewis of Mount Sinai School of Medicine, New York.
The review aims "to shed light on the recent paradigm shift to the use of endoscopy in the diagnosis and management of patients with obscure GI bleeding," the document says. Before the availability of wireless video capsule endoscopy and double-balloon enteroscopy (DBE), techniques that have "revolutionized the management of such patients," diagnosis and management of obscure GI bleeding presented greater challenges. Capsule endoscopy has made it possible to detect lesions such as small intestinal arteriovenous malformations (AVMs), and DBE has made treatment of such lesions possible "without the need for intraoperative enteroscopy."
The two technologies, which were introduced over the past 5 years, have reduced diagnostic delays and provided "an opportunity to revisit the traditional definitions of the source of GI bleeding," as upper or lower GI bleeding, based on the location of the bleeding as either proximal or distal to the ligament of Treitz, the document says. Reclassifying GI bleeding and obscure GI bleeding into upper-, mid-, and lower-GI bleeding, instead of the traditional upper and lower GI bleeding classifications, "may be useful to improve our understanding of the problem."
Upper GI bleeding is defined as bleeding above the ampulla of Vater, which is within reach of an EGD; mid-GI bleeding is defined as small intestinal bleeding from the ampulla of Vater to the terminal ileum, which is best investigated by capsule endoscopy and DBE; and lower GI bleeding is defined as colonic bleeding, which can be evaluated by colonoscopy.
These two technological advances "have changed the way we approach patients with bleeding now," Dr. Raju said. "In the past, if EGD, colonoscopy, and small bowel series were negative, we could not do much further, and patients kept on bleeding," but now, when these tests are negative, the two new technologies can be used to examine the small intestine.
The inability to examine the small bowel was overcome by capsule endoscopy. "The detection rate has increased tremendously, but capsule endoscopy is limited in the sense that it can't offer any therapy."
DBE, which is not yet as widely available as capsule endoscopy in the United States, makes it possible to examine a lot more of the small intestine than in the past, and can also be used to administer treatment, such as cauterization of blood vessels, Dr. Raju said. DBE uses a 200-cm enteroscope, with latex balloons at the tip and overtube, which are inflated and deflated with air so that the balloons grip the intestinal wall and pleat the small intestine onto the endoscope, thereby allowing deep insertion of the endoscope," Dr. Raju said.
Cameron's erosion in large hiatal hernias, fundic varices, peptic ulcer disease, angiodysplasias, Dieulafoy lesion, and gastric antral vascular ectasia are among the lesions in the upper GI tract that are often overlooked, according to the review. Angiodysplasias and neoplasms are among the lesions missed during colonoscopy. In the small bowel, the etiology of bleeding is related to age, with younger patients more likely to have small intestinal tumors, Meckel's diverticulum, Dieulafoy lesions, and Crohn's disease. Patients older than 40 years are prone to bleeding from vascular causes, which account for up to 40% of cases, and from NSAID-induced bowel disease, the statement says.
The review includes sections on radiologic imaging, cross-sectional imaging, nuclear scans, angiography, endoscopic imaging, intraoperative enteroscopy, sonde enteroscopy, and push enteroscopy. There are also sections on cost, pharmacologic therapy, endoscopic intervention for AVMs, and angiographic therapy.
In the 2000 statement, progressive testing with bleeding scans and angiography was proposed for patients with active bleeding, and repeated endoscopy, enteroscopy, enteroclysis, or small bowel series was proposed for patients not actively bleeding. Intraoperative enteroscopy was suggested for patients with continued blood loss.
The new statement says that evaluation of the patient with obscure GI bleeding depends on the extent of the bleeding and the patient's age. For example, among the recommendations are that patients with occult GI blood loss who are not anemic, "most likely do not require evaluation beyond colonoscopy," unless they also have upper GI tract symptoms. The cause of bleeding in younger patients should be investigated aggressively, because small bowel tumors are the most common cause of obscure bleeding in people under age 50, and capsule endoscopy can diagnose such tumors early--although this approach may overlook other small bowel lesions. These patients need to be followed closely, repeating the study if necessary.
The position statement also says that repeat endoscopy "can be worthwhile" in patients with obscure GI bleeding and associated anemia or overt bleeding with melena or maroon blood per rectum.
When all the results of standard examinations--EGD and colonoscopy-- are negative, "the small bowel may be assumed to be the source of blood loss and capsule endoscopy should be the third test in the evaluation of patients with GI bleeding," the statement says. Negative findings for the small bowel in a patient with active bleeding could indicate that the bleeding is colonic or gastric. In a patient with active bleeding in the small intestine, "the capsule will guide further evaluation and therapy."
"The role of small bowel series, enteroclysis, cross-sectional imaging, and nuclear scans in the evaluation of obscure GI bleeding has declined substantially with the advent of capsule endoscopy because of its extremely low diagnostic yield," the position statement says.
Outcome studies are needed, but it appears that "early use of capsule endoscopy would not only allow more rapid diagnosis and thus improved patient care but could also lessen the costs associated with obscure bleeding." This approach would avoid repeated colonoscopy and upper endoscopy, and "with a diagnosis, repeat hospitalizations and transfusions could be averted."
The statement describes early experience with DBE as "encouraging," concluding that more studies on the cost-effectiveness of the two technologies "will help us define the choice of investigation and management of these patients."
"Hopefully, these advances will transfer into better care and less hospitalizations, and more definitive therapy early on" for obscure GI bleeding, Dr. Raju said.