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The role of endoscopyin the patient with lower gastrointestinal bleeding
American Society For Gastrointestinal Endoscopy
SOCIETY FO R
ST
RO
O
GA
PY
ICAN ER AM
INT
E STIN A L E N D
OS
C
THE ROLE OF ENDOSCOPY IN THE PATIENT WITH LOWER GASTROINTESTINAL BLEEDING Introduction: Endoscopy is valuable in the diagnosis of the cause of lower gastrointestinal bleeding, and it offers the opportunity for treatment of selected patients with this problem. Endoscopic procedures must be integrated with other studies to reach a correct diagnosis rapidly, safely, and economically. In all patients, evaluation begins with a history and physical examination. The sequence of other tests depends on many factors, especially the rate of bleeding. CHRONIC BLEEDING Chronic lower gastrointestinal bleeding is the passage of blood per rectum over a period of several days or longer, and usually implies intermittent or slow loss of blood. The patient with chronic bleeding can have occult fecal blood, occasional episodes of black or maroon stools, or small quantities of visible blood per rectum. Occult fecal blood Neoplasia of the gastrointestinal tract, especially the large bowel, is the most important concern in a patient over the age of 50 with occult fecal blood. While a digital rectal examination and anoscopy are advisable, they do not exclude a more proximal source of blood loss. Examination of the entire rectum and colon must be carried out. Three randomized trials have shown that examination of the colon in patients with positive occult blood in stool results in reduction in mortality from colon cancer (1-3). The more proximal colon must be evaluated by colonoscopy or double contrast barium x-rays. If xrays are obtained and they do not reveal a potential bleeding site, colonoscopy should be performed, since a carcinoma, polyp, inflammatory lesion, or other source of blood loss is identified in 20%-40% of such patients (4-9). If barium x-rays do demonstrate a lesion, colonoscopy usually is necessary to confirm its presence and nature (biopsy of a neoplasm) and, in some cases, to treat a lesion (polypectomy). The VOLUME 48, NO. 6, 1998
therapeutic potential of colonoscopy, including polypectomy and control of bleeding sites by electrocoagulation or photocoagulation, and the eventual need for colonoscopy if sigmoidoscopy or barium enema are positive, strongly favors colonoscopy over flexible sigmoidoscopy and contrast enema x-rays in the initial evaluation of patients with occult rectal bleeding (10-14). Conversely, if colonoscopy cannot be completed to the cecum or is suboptimal, air-contrast barium enema should be obtained before investigating the upper gastrointestinal tract. Upper endoscopy to check for an upper gastrointestinal source of bleeding should be considered if a colonic source is not found, particularly in a patient who is symptomatic or anemic(15). The occasional patient with clinically significant chronic bleeding from the small intestine may be diagnosed by barium x-rays, enteroclysis, angiography, nuclear medicine scans, small bowel endoscopy (push or sonde enteroscopy), or intraoperative maneuvers including operative endoscopy (16). Intermittent melena The diagnostic evaluation of a patient with intermittent melena should begin with upper endoscopy because an upper tract lesion is most likely in this setting. Lower tract evaluation and small bowel studies similar to that described for occult bleeding are indicated if no upper source is found (8). Scant hematochezia Chronic intermittent passage of small amounts of visible red blood is the most common pattern of lower gastrointestinal bleeding. The majority of such patients are bleeding from an anal lesion (e.g. hemorrhoids, anal fissure etc.), and most of the others are bleeding from lesions in the rectum or distal colon. Historical features are often helpful in differentiating among possible diagnoses. For example, hemorrhoids typically present as bright red spots on toilet paper or bright red blood dripping into the toilet GASTROINTESTINAL ENDOSCOPY
685
bowl. On the other hand, severe pain (out of proportion of the clinical findings) during and after defecation along with scant amount of bright red bleeding is characteristically seen in an anal fissure (17). The diagnostic evaluation of patients with scant hematochezia includes careful inspection of the anus, digital rectal examination, anoscopy, and sigmoidoscopy. The diagnostic yield is higher when evaluation is performed during a bleeding episode. If flexible sigmoidoscopy is performed, the instrument should be retroflexed in the rectum to view the anorectal junction from above, unless an adequate examination with an anoscope has been done. The entire colon should be evaluated by colonoscopy or air-contrast barium enema if a convincing source of blood is not found in the anorectum or sigmoid. The decision to obtain one of these studies is based on the patient’s age, general condition and the presence of risk factors for neoplasia. For example, young patients with scant hematochezia and an obvious anal bleeding site need not usually undergo colonoscopy or x-ray, whereas middle-aged and older individuals may need further examination even in the presence of an anal lesion. If colonoscopy or x-rays are not obtained initially, persistent or recurrent bleeding should prompt more thorough evaluation. ACUTE BLEEDING Acute lower gastrointestinal bleeding is arbitrarily defined as bleeding of less than 3 days’ duration. For the purpose of this discussion, acute bleeding is subdivided by amount lost into either moderate bleeding or massive bleeding. Moderate bleeding Acute loss of blood per rectum without hemodynamic instability and which is not sufficient to require immediate transfusion, can be termed moderate. Moderate blood loss comprises the majority of acute bleeding instances and is characterized by either the spontaneous cessation of rapid bleeding after a brief period or by rectal bleeding of slower rate but longer duration. Moderate bleeding infrequently leads to significant hemodynamic changes in the affected individual, and one may therefore proceed immediately with diagnostic tests. Early in the evaluation of acute bleeding, upper or lower gastrointestinal barium contrast studies are not advised because they will interfere with subsequent endoscopic or angiographic studies which might have been diagnostic if done first. The anus and rectum may be the source of moderate blood loss and must be examined carefully. The presence of an anorectal lesion, however, does not exclude a more proximal bleeding site and 686
GASTROINTESTINAL ENDOSCOPY
colonoscopy should be performed. Initial colonoscopic examination of the unprepared bowel is difficult and frequently unsuccessful but will occasionally demonstrate an area of sharp demarcation between feces free of gross blood proximally and liquid or clotted blood distally. Colonoscopy will more likely identify a bleeding site if the patient is first rapidly prepared with oral lavage and is preferred to an unprepped procedure. If complete colonoscopy is negative, and if bleeding does not recur within a few days, the alternatives are to monitor the patient carefully, to obtain other imaging studies detailed below, or repeat colonoscopic examination if bleeding recurs. Severe bleeding A small number of patients have acute loss of large volumes of blood per rectum from a source in the upper or lower gastrointestinal tract. These patients have lost at least 15% or more of their blood volume and have associated hemodynamic instability. The first priority is to stabilize the patient with intravenous fluids and transfusions if necessary. The diagnostic work-up begins while these resuscitative efforts are underway or as soon as the patient is stable, depending on the urgency of the situation. A nasogastric tube should be inserted and the gastric aspirate observed for visible blood. A non-bloody nasogastric tube aspirate does not exclude an upper source of gastrointestinal bleeding; however the presence of bile in the aspirate makes upper GI tract bleeding very unlikely. Upper endoscopy should be performed, even if the stomach contains no blood, if evaluation for a lower bleeding source is negative or if an upper bleeding source is suspected. Barium contrast studies are not indicated at this time. Most patients will require evaluation of the colon. There are two strategies for evaluation of the colon in these patients: (i) colonoscopy (18), and (ii) angiography, with or without a preceding radionuclide scan (sulfur colloid or technetium-pertechnetate labeled red cells). The strategy of emergency colonoscopy has the following advantages: (i) it discloses a bleeding lesion of the colon in 50%-70% of patients examined (19-21); (ii) definitive treatment of an identified lesion by snare cautery, fulguration with electrocautery, heater probe, injection therapy, or laser photocoagulation is often possible during the emergent or a subsequent elective colonoscopic procedure; and (iii) massively bleeding lesions that have stopped will more often be identifiable by colonoscopy than by angiography. Disadvantages of colonoscopy include the need for available and skilled endoscopists, an increased risk VOLUME 48, NO. 6, 1998
of perforation when colonoscopy is performed in an ill patient with blood in the colon, the delay of 1-3 hours required to prepare the colon, and the possibility of unsuccessful diagnosis or treatment because of technical problems. The colon is cleansed by enemas or, preferably, by lavage with 3-4 liters of electrolyte solution given orally or through a nasogastric tube. The delay required for preparation is rarely a significant disadvantage since other necessary resuscitative measures may be carried out at the same time, and only rare patients bleed so rapidly that a delay of a few hours jeopardizes hemodynamic stability. Angiography has the advantages of (i) localization of a rapidly bleeding site, and (ii) potential for treatment of the hemorrhage by infusion or embolization. Many angiographers prefer that a nuclear medicine scan be obtained first, but the role of nuclear medicine scanning prior to angiography in gastrointestinal bleeding is not firmly established. The 99mTc-pertechnate labeled red blood cell (RBC) scan can detect bleeding rates as low as 0.1 to 0.4 ml/min(22,23). Disadvantages of the bleeding scan include delay in instituting specific therapy or performing angiography, low rate of localization of the actual site of bleeding, and lack of therapeutic intervention(24). There have been no randomized studies that compare the utility of a RBC scan prior to angiography and angiography alone in patients with significant lower gastrointestinal bleeding. If the RBC scan is negative, the likelihood of demonstrating a bleeding point angiographically is lower than if a scan is positive and would favor proceeding to colonoscopy. Disadvantages of angiography include the requirement for available and skilled imaging experts on short notice; risks of contrast media allergic reactions or nephrotoxicity as a consequence of prolonged or repeated studies; other complications of an invasive procedure, e.g., vascular thrombosis; and the possibility of unsuccessful diagnosis or treatment because of anatomic or other technical problems. An additional disadvantage is the necessity to move a patient from a critical care area to a fluoroscopy unit for the procedure. The decision regarding initial evaluation by either colonoscopy, angiography or nuclear scans is a clinical one and does not preclude subsequent examination by the alternative technique. The success in detecting and treating a bleeding site during colonoscopy and angiography may vary in different institutions, and initial selection of one of these modalities will therefore depend on local expertise, because comparative long-term morbidity and mortality data are not yet available. Although retrospective data suggest significant cost reduction by VOLUME 48, NO. 6, 1998
emergent colonoscopy in the management of patients with significant lower gastrointestinal bleeding, no prospective data are available on the economic impact of early colonoscopy versus angiography in this group of patients. Regardless of whether colonoscopy and/or angiography has been performed, if significant bleeding continues, emergent surgical intervention may be needed. Surgical intervention without preoperative attempts to identify the site of bleeding by colonoscopy or angiography should be reserved for extreme cases, because the mortality and rebleeding rates in this group of patients may be high. Identification of the bleeding site prior to surgery decreases the morbidity and mortality in patients with severe lower gastrointestinal bleeding. The principal colonic causes of significant bleeding per rectum are diverticulosis or vascular malformations (25). Less commonly, colonic neoplasms, colitis, radiation colopathy, hemorrhoids, intramural lesions, or colonic ulcers may be the source of significant gastrointestinal bleeding. Postpolypectomy bleeding can be significant and may occur up to 14 days after colonoscopic polypectomy (26). In the absence of an identifiable source of bleeding from the colon, esophagus, stomach, or proximal duodenum, a small bowel cause of bleeding should be considered. Diagnostic considerations include Meckel’s diverticulum, vascular malformations, ulcers, Crohn’s disease, lymphoma, and other neoplasms. An aorto- enteric fistula with bleeding from the distal duodenum should be considered in patients with a synthetic vascular graft as a result of a prior aortic aneurysm repair. When a small bowel source of significant bleeding is suspected, enteroscopy should be considered. Barium studies of the small bowel may be appropriate if endoscopic evaluation fails to identify a bleeding source. Summary: In most patients, colonoscopy is the procedure of choice in the diagnosis of active lower gastrointestinal bleeding. Angiography is appropriate when colonoscopy cannot be performed, or has not identified a site in the setting of active bleeding. Upper endoscopy is indicated when an upper gastrointestinal bleeding source is suspected, or evaluation of the colon has been negative. When other studies have failed to identify the bleeding source, small bowel lesions should be considered. REFERENCES 1. Mandel JS, Bond JH, Church TR, et al. Reducing mortality from colorectal cancer by screening for fecal occult blood. N Engl J Med 1993;328:1365-71 2. Hardcastle JD, Chamberlain JO, Robinson MHE, et al. Randomized controlled trial of fecal-occult blood screening for colorectal cancer. Lancet 1996;348:1472-7 GASTROINTESTINAL ENDOSCOPY
687
3. Kronborg O, Fenger C, Olsen J, et al. Randomized study of screening for colorectal cancer with fecal-occult blood test. Lancet 1996;348:1467-71 4. Brand EJ, Sullivan BH Jr, Sivak MV Jr, Rankin GB. Colonoscopy in the diagnosis of unexplained rectal bleeding. Ann Surg 1980;192:111. 5. Knutson CO, Max MH. Value of colonoscopy in patients with rectal blood loss unexplained by rigid proctosigmoidoscopy and barium contrast examination. Am J Surg 1980;139:84. 6. Max MH, Richardson JD, Flint LM Jr, Knutson CO, Schwesinger W. Colonoscopic diagnosis of angiodysplasias of the gastrointestinal tract. Surg Gynecol Obstet 1981;152:195. 7. Swarbrick ET, Hunt RH. Rectal bleeding. In: Hunt RH, Waye D, eds. Colonoscopy: techniques, clinical practice and color atlas. London: Chapman and Hall, 1981:267-M. 8. Tedesco FJ, Pickens CA, Griffin JW Jr, Sivak MV Jr, Sullivan VH Jr. Role of colonoscopy in patients with unexplained melena:an analysis of 53 patients. Gastrointest Endosc 1981;27:221. 9. Todd GJ, Forde KA. Lower gastrointestinal bleeding with negative or inconclusive radiographic studies: the role of colonoscopy. Am J Surg 1971;138:627. 10. Fruhmorgen P. Therapeutic colonoscopy. In: Hunt RH, Waye JD, eds. Colonoscopy: techniques, clinical practice and color atlas. London: Chapman and Hall, 1981:199-235. 11. Howard OM, Buchanan JD, Hunt RH. Angiodysplasia of the colon: experience of 26 cases. Lancet 1982;2:16. 12. Rogers BHG. Endoscopic diagnosis and therapy of mucosal vascular abnormalities of the gastrointestinal tract occurring in elderly patients and associated with cardiac, vascular and pulmonary disease. Gastrointest Endosc 1980; 25:134. 13. Brandt LJ, Boley SJ. The role of colonoscopy in the diagnosis and management of lower intestinal bleeding. Scand J Gastroenterol 1984; 19(suppl 102):61-70. 14. Tedesco FJ, Gottfried EB, Corless JK, Brownstein RE. Prospective evaluation of hospice patients with nonactive lower intestinal bleeding- timing and role of barium enema and colonoscopy. Gastrointest Endosc 1984;30:281-3.
688
GASTROINTESTINAL ENDOSCOPY
15. Stroehlein J, Goulston K, Hunt RH. Diagnostic approach to evaluating the cause of a positive fecal occult blood test in cancer. Cancer J Clin 1984;34:148-58. 16. Lau WY, Fan ST, Chu KW, et al. Intraoperative fiber-optic enteroscopy for bleeding lesions in the small bowel. Br J Surgery 1986;73:217 17. Barnett JL, Raper SE. Anorectal diseases. In: Yamada, Alpers, Owyang, Powell DW, Silverstein FE (eds). Textbook of Gastroenterology. 1995;Philadelphia, p 2027-50 18. Treat MR, Forde KA. Colonoscopy, technetium scanning, and angiography in acute rectal bleeding-. an algorithm for their combined use. Surg Gastroenterol 1983;2:135-8. 19. Forde KA. Colonoscopy in acute rectal bleeding. Gastrointest Endosc 1981;27:219. 20. Rossini FP, Ferrari A. Emergency colonoscopy. In: Hunt RH, Waye JD, eds. Colonoscopy: techniques, clinical practice and color atlas. London: Chapman and Hall, 1981:289-99. 21. Jensen DM, Machicado GA, Tapia JI. Emergent colonoscopy in patients with severe hematochezia. Gastrointest Endosc 1983;29: 177. 22. McKusick KA, Froelich J, Callahan RJ, et al. Tc-99m red blood cells for detection of gastrointestinal bleeding: experience with 80 patients. Am J Roentgenol 1981;137:1113 23. Rantis Jr. PC, Harford FJ, Wagner RH, et al. Technetiumlabelled red blood cell scintigraphy:is it useful in acute lower gastrointestinal bleeding? Int J Colorectal Dis 1995;10:210-215 24. Ho JE, Konieczny KM. The sodium pertechnate Tc 99m scan: an aid in the evaluation of gastrointestinal bleeding. Pediatrics 1975;56:34 25. Jensen DM, Machicado GA. Colonoscopy for diagnosis and treatment of severe lower gastrointestinal bleeding. Routine Outcomes and cost analysis. Gastrointest Endosc Clin N Am 1997;7:477-98 26. Rex DK, Lewis BS, Waye JD. Colonoscopy and endoscopic therapy for delayed postpolypectomy hemorrhage. Gastrointest Endosc 1992;38:127-129
VOLUME 48, NO. 6, 1998
SOCIETY FO R
ST
RO
O
GA
PY
ICAN ER AM
INT
E STIN A L E N D
OS
C
THE ROLE OF ENDOSCOPY IN THE PATIENT WITH LOWER GASTROINTESTINAL BLEEDING Introduction: Endoscopy is valuable in the diagnosis of the cause of lower gastrointestinal bleeding, and it offers the opportunity for treatment of selected patients with this problem. Endoscopic procedures must be integrated with other studies to reach a correct diagnosis rapidly, safely, and economically. In all patients, evaluation begins with a history and physical examination. The sequence of other tests depends on many factors, especially the rate of bleeding. CHRONIC BLEEDING Chronic lower gastrointestinal bleeding is the passage of blood per rectum over a period of several days or longer, and usually implies intermittent or slow loss of blood. The patient with chronic bleeding can have occult fecal blood, occasional episodes of black or maroon stools, or small quantities of visible blood per rectum. Occult fecal blood Neoplasia of the gastrointestinal tract, especially the large bowel, is the most important concern in a patient over the age of 50 with occult fecal blood. While a digital rectal examination and anoscopy are advisable, they do not exclude a more proximal source of blood loss. Examination of the entire rectum and colon must be carried out. Three randomized trials have shown that examination of the colon in patients with positive occult blood in stool results in reduction in mortality from colon cancer (1-3). The more proximal colon must be evaluated by colonoscopy or double contrast barium x-rays. If xrays are obtained and they do not reveal a potential bleeding site, colonoscopy should be performed, since a carcinoma, polyp, inflammatory lesion, or other source of blood loss is identified in 20%-40% of such patients (4-9). If barium x-rays do demonstrate a lesion, colonoscopy usually is necessary to confirm its presence and nature (biopsy of a neoplasm) and, in some cases, to treat a lesion (polypectomy). The VOLUME 48, NO. 6, 1998
therapeutic potential of colonoscopy, including polypectomy and control of bleeding sites by electrocoagulation or photocoagulation, and the eventual need for colonoscopy if sigmoidoscopy or barium enema are positive, strongly favors colonoscopy over flexible sigmoidoscopy and contrast enema x-rays in the initial evaluation of patients with occult rectal bleeding (10-14). Conversely, if colonoscopy cannot be completed to the cecum or is suboptimal, air-contrast barium enema should be obtained before investigating the upper gastrointestinal tract. Upper endoscopy to check for an upper gastrointestinal source of bleeding should be considered if a colonic source is not found, particularly in a patient who is symptomatic or anemic(15). The occasional patient with clinically significant chronic bleeding from the small intestine may be diagnosed by barium x-rays, enteroclysis, angiography, nuclear medicine scans, small bowel endoscopy (push or sonde enteroscopy), or intraoperative maneuvers including operative endoscopy (16). Intermittent melena The diagnostic evaluation of a patient with intermittent melena should begin with upper endoscopy because an upper tract lesion is most likely in this setting. Lower tract evaluation and small bowel studies similar to that described for occult bleeding are indicated if no upper source is found (8). Scant hematochezia Chronic intermittent passage of small amounts of visible red blood is the most common pattern of lower gastrointestinal bleeding. The majority of such patients are bleeding from an anal lesion (e.g. hemorrhoids, anal fissure etc.), and most of the others are bleeding from lesions in the rectum or distal colon. Historical features are often helpful in differentiating among possible diagnoses. For example, hemorrhoids typically present as bright red spots on toilet paper or bright red blood dripping into the toilet GASTROINTESTINAL ENDOSCOPY
685
bowl. On the other hand, severe pain (out of proportion of the clinical findings) during and after defecation along with scant amount of bright red bleeding is characteristically seen in an anal fissure (17). The diagnostic evaluation of patients with scant hematochezia includes careful inspection of the anus, digital rectal examination, anoscopy, and sigmoidoscopy. The diagnostic yield is higher when evaluation is performed during a bleeding episode. If flexible sigmoidoscopy is performed, the instrument should be retroflexed in the rectum to view the anorectal junction from above, unless an adequate examination with an anoscope has been done. The entire colon should be evaluated by colonoscopy or air-contrast barium enema if a convincing source of blood is not found in the anorectum or sigmoid. The decision to obtain one of these studies is based on the patient’s age, general condition and the presence of risk factors for neoplasia. For example, young patients with scant hematochezia and an obvious anal bleeding site need not usually undergo colonoscopy or x-ray, whereas middle-aged and older individuals may need further examination even in the presence of an anal lesion. If colonoscopy or x-rays are not obtained initially, persistent or recurrent bleeding should prompt more thorough evaluation. ACUTE BLEEDING Acute lower gastrointestinal bleeding is arbitrarily defined as bleeding of less than 3 days’ duration. For the purpose of this discussion, acute bleeding is subdivided by amount lost into either moderate bleeding or massive bleeding. Moderate bleeding Acute loss of blood per rectum without hemodynamic instability and which is not sufficient to require immediate transfusion, can be termed moderate. Moderate blood loss comprises the majority of acute bleeding instances and is characterized by either the spontaneous cessation of rapid bleeding after a brief period or by rectal bleeding of slower rate but longer duration. Moderate bleeding infrequently leads to significant hemodynamic changes in the affected individual, and one may therefore proceed immediately with diagnostic tests. Early in the evaluation of acute bleeding, upper or lower gastrointestinal barium contrast studies are not advised because they will interfere with subsequent endoscopic or angiographic studies which might have been diagnostic if done first. The anus and rectum may be the source of moderate blood loss and must be examined carefully. The presence of an anorectal lesion, however, does not exclude a more proximal bleeding site and 686
GASTROINTESTINAL ENDOSCOPY
colonoscopy should be performed. Initial colonoscopic examination of the unprepared bowel is difficult and frequently unsuccessful but will occasionally demonstrate an area of sharp demarcation between feces free of gross blood proximally and liquid or clotted blood distally. Colonoscopy will more likely identify a bleeding site if the patient is first rapidly prepared with oral lavage and is preferred to an unprepped procedure. If complete colonoscopy is negative, and if bleeding does not recur within a few days, the alternatives are to monitor the patient carefully, to obtain other imaging studies detailed below, or repeat colonoscopic examination if bleeding recurs. Severe bleeding A small number of patients have acute loss of large volumes of blood per rectum from a source in the upper or lower gastrointestinal tract. These patients have lost at least 15% or more of their blood volume and have associated hemodynamic instability. The first priority is to stabilize the patient with intravenous fluids and transfusions if necessary. The diagnostic work-up begins while these resuscitative efforts are underway or as soon as the patient is stable, depending on the urgency of the situation. A nasogastric tube should be inserted and the gastric aspirate observed for visible blood. A non-bloody nasogastric tube aspirate does not exclude an upper source of gastrointestinal bleeding; however the presence of bile in the aspirate makes upper GI tract bleeding very unlikely. Upper endoscopy should be performed, even if the stomach contains no blood, if evaluation for a lower bleeding source is negative or if an upper bleeding source is suspected. Barium contrast studies are not indicated at this time. Most patients will require evaluation of the colon. There are two strategies for evaluation of the colon in these patients: (i) colonoscopy (18), and (ii) angiography, with or without a preceding radionuclide scan (sulfur colloid or technetium-pertechnetate labeled red cells). The strategy of emergency colonoscopy has the following advantages: (i) it discloses a bleeding lesion of the colon in 50%-70% of patients examined (19-21); (ii) definitive treatment of an identified lesion by snare cautery, fulguration with electrocautery, heater probe, injection therapy, or laser photocoagulation is often possible during the emergent or a subsequent elective colonoscopic procedure; and (iii) massively bleeding lesions that have stopped will more often be identifiable by colonoscopy than by angiography. Disadvantages of colonoscopy include the need for available and skilled endoscopists, an increased risk VOLUME 48, NO. 6, 1998
of perforation when colonoscopy is performed in an ill patient with blood in the colon, the delay of 1-3 hours required to prepare the colon, and the possibility of unsuccessful diagnosis or treatment because of technical problems. The colon is cleansed by enemas or, preferably, by lavage with 3-4 liters of electrolyte solution given orally or through a nasogastric tube. The delay required for preparation is rarely a significant disadvantage since other necessary resuscitative measures may be carried out at the same time, and only rare patients bleed so rapidly that a delay of a few hours jeopardizes hemodynamic stability. Angiography has the advantages of (i) localization of a rapidly bleeding site, and (ii) potential for treatment of the hemorrhage by infusion or embolization. Many angiographers prefer that a nuclear medicine scan be obtained first, but the role of nuclear medicine scanning prior to angiography in gastrointestinal bleeding is not firmly established. The 99mTc-pertechnate labeled red blood cell (RBC) scan can detect bleeding rates as low as 0.1 to 0.4 ml/min(22,23). Disadvantages of the bleeding scan include delay in instituting specific therapy or performing angiography, low rate of localization of the actual site of bleeding, and lack of therapeutic intervention(24). There have been no randomized studies that compare the utility of a RBC scan prior to angiography and angiography alone in patients with significant lower gastrointestinal bleeding. If the RBC scan is negative, the likelihood of demonstrating a bleeding point angiographically is lower than if a scan is positive and would favor proceeding to colonoscopy. Disadvantages of angiography include the requirement for available and skilled imaging experts on short notice; risks of contrast media allergic reactions or nephrotoxicity as a consequence of prolonged or repeated studies; other complications of an invasive procedure, e.g., vascular thrombosis; and the possibility of unsuccessful diagnosis or treatment because of anatomic or other technical problems. An additional disadvantage is the necessity to move a patient from a critical care area to a fluoroscopy unit for the procedure. The decision regarding initial evaluation by either colonoscopy, angiography or nuclear scans is a clinical one and does not preclude subsequent examination by the alternative technique. The success in detecting and treating a bleeding site during colonoscopy and angiography may vary in different institutions, and initial selection of one of these modalities will therefore depend on local expertise, because comparative long-term morbidity and mortality data are not yet available. Although retrospective data suggest significant cost reduction by VOLUME 48, NO. 6, 1998
emergent colonoscopy in the management of patients with significant lower gastrointestinal bleeding, no prospective data are available on the economic impact of early colonoscopy versus angiography in this group of patients. Regardless of whether colonoscopy and/or angiography has been performed, if significant bleeding continues, emergent surgical intervention may be needed. Surgical intervention without preoperative attempts to identify the site of bleeding by colonoscopy or angiography should be reserved for extreme cases, because the mortality and rebleeding rates in this group of patients may be high. Identification of the bleeding site prior to surgery decreases the morbidity and mortality in patients with severe lower gastrointestinal bleeding. The principal colonic causes of significant bleeding per rectum are diverticulosis or vascular malformations (25). Less commonly, colonic neoplasms, colitis, radiation colopathy, hemorrhoids, intramural lesions, or colonic ulcers may be the source of significant gastrointestinal bleeding. Postpolypectomy bleeding can be significant and may occur up to 14 days after colonoscopic polypectomy (26). In the absence of an identifiable source of bleeding from the colon, esophagus, stomach, or proximal duodenum, a small bowel cause of bleeding should be considered. Diagnostic considerations include Meckel’s diverticulum, vascular malformations, ulcers, Crohn’s disease, lymphoma, and other neoplasms. An aorto- enteric fistula with bleeding from the distal duodenum should be considered in patients with a synthetic vascular graft as a result of a prior aortic aneurysm repair. When a small bowel source of significant bleeding is suspected, enteroscopy should be considered. Barium studies of the small bowel may be appropriate if endoscopic evaluation fails to identify a bleeding source. Summary: In most patients, colonoscopy is the procedure of choice in the diagnosis of active lower gastrointestinal bleeding. Angiography is appropriate when colonoscopy cannot be performed, or has not identified a site in the setting of active bleeding. Upper endoscopy is indicated when an upper gastrointestinal bleeding source is suspected, or evaluation of the colon has been negative. When other studies have failed to identify the bleeding source, small bowel lesions should be considered. REFERENCES 1. Mandel JS, Bond JH, Church TR, et al. Reducing mortality from colorectal cancer by screening for fecal occult blood. N Engl J Med 1993;328:1365-71 2. Hardcastle JD, Chamberlain JO, Robinson MHE, et al. Randomized controlled trial of fecal-occult blood screening for colorectal cancer. Lancet 1996;348:1472-7 GASTROINTESTINAL ENDOSCOPY
687
3. Kronborg O, Fenger C, Olsen J, et al. Randomized study of screening for colorectal cancer with fecal-occult blood test. Lancet 1996;348:1467-71 4. Brand EJ, Sullivan BH Jr, Sivak MV Jr, Rankin GB. Colonoscopy in the diagnosis of unexplained rectal bleeding. Ann Surg 1980;192:111. 5. Knutson CO, Max MH. Value of colonoscopy in patients with rectal blood loss unexplained by rigid proctosigmoidoscopy and barium contrast examination. Am J Surg 1980;139:84. 6. Max MH, Richardson JD, Flint LM Jr, Knutson CO, Schwesinger W. Colonoscopic diagnosis of angiodysplasias of the gastrointestinal tract. Surg Gynecol Obstet 1981;152:195. 7. Swarbrick ET, Hunt RH. Rectal bleeding. In: Hunt RH, Waye D, eds. Colonoscopy: techniques, clinical practice and color atlas. London: Chapman and Hall, 1981:267-M. 8. Tedesco FJ, Pickens CA, Griffin JW Jr, Sivak MV Jr, Sullivan VH Jr. Role of colonoscopy in patients with unexplained melena:an analysis of 53 patients. Gastrointest Endosc 1981;27:221. 9. Todd GJ, Forde KA. Lower gastrointestinal bleeding with negative or inconclusive radiographic studies: the role of colonoscopy. Am J Surg 1971;138:627. 10. Fruhmorgen P. Therapeutic colonoscopy. In: Hunt RH, Waye JD, eds. Colonoscopy: techniques, clinical practice and color atlas. London: Chapman and Hall, 1981:199-235. 11. Howard OM, Buchanan JD, Hunt RH. Angiodysplasia of the colon: experience of 26 cases. Lancet 1982;2:16. 12. Rogers BHG. Endoscopic diagnosis and therapy of mucosal vascular abnormalities of the gastrointestinal tract occurring in elderly patients and associated with cardiac, vascular and pulmonary disease. Gastrointest Endosc 1980; 25:134. 13. Brandt LJ, Boley SJ. The role of colonoscopy in the diagnosis and management of lower intestinal bleeding. Scand J Gastroenterol 1984; 19(suppl 102):61-70. 14. Tedesco FJ, Gottfried EB, Corless JK, Brownstein RE. Prospective evaluation of hospice patients with nonactive lower intestinal bleeding- timing and role of barium enema and colonoscopy. Gastrointest Endosc 1984;30:281-3.
688
GASTROINTESTINAL ENDOSCOPY
15. Stroehlein J, Goulston K, Hunt RH. Diagnostic approach to evaluating the cause of a positive fecal occult blood test in cancer. Cancer J Clin 1984;34:148-58. 16. Lau WY, Fan ST, Chu KW, et al. Intraoperative fiber-optic enteroscopy for bleeding lesions in the small bowel. Br J Surgery 1986;73:217 17. Barnett JL, Raper SE. Anorectal diseases. In: Yamada, Alpers, Owyang, Powell DW, Silverstein FE (eds). Textbook of Gastroenterology. 1995;Philadelphia, p 2027-50 18. Treat MR, Forde KA. Colonoscopy, technetium scanning, and angiography in acute rectal bleeding-. an algorithm for their combined use. Surg Gastroenterol 1983;2:135-8. 19. Forde KA. Colonoscopy in acute rectal bleeding. Gastrointest Endosc 1981;27:219. 20. Rossini FP, Ferrari A. Emergency colonoscopy. In: Hunt RH, Waye JD, eds. Colonoscopy: techniques, clinical practice and color atlas. London: Chapman and Hall, 1981:289-99. 21. Jensen DM, Machicado GA, Tapia JI. Emergent colonoscopy in patients with severe hematochezia. Gastrointest Endosc 1983;29: 177. 22. McKusick KA, Froelich J, Callahan RJ, et al. Tc-99m red blood cells for detection of gastrointestinal bleeding: experience with 80 patients. Am J Roentgenol 1981;137:1113 23. Rantis Jr. PC, Harford FJ, Wagner RH, et al. Technetiumlabelled red blood cell scintigraphy:is it useful in acute lower gastrointestinal bleeding? Int J Colorectal Dis 1995;10:210-215 24. Ho JE, Konieczny KM. The sodium pertechnate Tc 99m scan: an aid in the evaluation of gastrointestinal bleeding. Pediatrics 1975;56:34 25. Jensen DM, Machicado GA. Colonoscopy for diagnosis and treatment of severe lower gastrointestinal bleeding. Routine Outcomes and cost analysis. Gastrointest Endosc Clin N Am 1997;7:477-98 26. Rex DK, Lewis BS, Waye JD. Colonoscopy and endoscopic therapy for delayed postpolypectomy hemorrhage. Gastrointest Endosc 1992;38:127-129
VOLUME 48, NO. 6, 1998