Stool guaiac test

Last updated
Stool guaiac test
Guaiac01.jpg
Guaiac cards and bottle of developer that contains hydrogen peroxide
MedlinePlus 003393
HCPCS-L2 G0394
Both square test areas in the upper area of the card show the intense blue color of a positive result. The lower two smaller circular areas on the orange stripe are analytical control reactions, positive on the left and negative on the right, that help assure that the card and developer bottle have been maintained in proper conditions and have not been damaged before the test is performed. Guaiac test.jpg
Both square test areas in the upper area of the card show the intense blue color of a positive result. The lower two smaller circular areas on the orange stripe are analytical control reactions, positive on the left and negative on the right, that help assure that the card and developer bottle have been maintained in proper conditions and have not been damaged before the test is performed.

The stool guaiac test or guaiac fecal occult blood test (gFOBT) is one of several methods that detects the presence of fecal occult blood [1] (blood invisible in the feces). [2] The test involves placing a fecal sample on guaiac paper (containing a phenolic compound, alpha-guaiaconic acid, extracted from the wood resin of Guaiacum trees) and applying hydrogen peroxide which, in the presence of blood, yields a blue reaction product within seconds.

Contents

The American College of Gastroenterology has recommended the abandoning of gFOBT testing as a colorectal cancer screening tool, in favor of the fecal immunochemical test (FIT). [3] Though the FIT is preferred, even the guaiac FOB testing of average risk populations may have been sufficient to reduce the mortality associated with colon cancer by about 25%. [4] With this lower efficacy, it was not always cost effective to screen a large population with gFOBT. [5] [6] [7] [8]

Methodology

The stool guaiac test involves fasting from iron supplements, red meat (the blood it contains can turn the test positive), certain vegetables (which contain a chemical with peroxidase properties that can turn the test positive), and vitamin C and citrus fruits (which can turn the test falsely negative) for a period of time before the test. It has been suggested that cucumber, cauliflower and horseradish, and often other vegetables, should be avoided for three days before the test. [9]

In testing, feces are applied to a thick piece of paper attached to a thin film coated with guaiac. Either the patient or medical professional smears a small fecal sample on to the film. The fecal sample is obtained by catching the stool and transferring a sample with an applicator. Digital rectal examination specimens are also used but this method is discouraged for colorectal cancer screening due to very poor performance characteristics. [10]

Both sides of the test card can be peeled open, to access the inner guaiac paper. One side of the card is marked for application of the stool and the other is for the developer fluid.[ citation needed ]

After applying the feces, one or two drops of hydrogen peroxide are then dripped on to the other side of the film, and it is observed for a rapid blue color change.[ citation needed ]

Chemistry

When the hydrogen peroxide is dripped on to the guaiac paper, it oxidizes the alpha-guaiaconic acid to a blue colored quinone. [11] [12] Normally, when no blood and no peroxidases or catalases from vegetables are present, this oxidation occurs very slowly. Heme, a component of hemoglobin found in blood, catalyzes this reaction, giving a result in about two seconds. Therefore, a positive test result is one where there is a quick and intense blue color change of the film.

Proposed oxidations of compounds in guaiac oil as explanation for the formation of the blue bis-methylenequinone as part of the guaiac test. Possible Guaiacum blue formation reactions.svg
Proposed oxidations of compounds in guaiac oil as explanation for the formation of the blue bis-methylenequinone as part of the guaiac test.

Analytical interpretation

The guaiac test can often be false-positive which is a positive test result when there is in fact no source of bleeding. This is particularly common if the recommended dietary preparation is not followed, as the heme in red meat or the peroxidase or catalase activity in vegetables, especially if uncooked, can cause analytical false positives.

Vitamin C can cause analytical false negatives due to its anti-oxidant properties inhibiting the color reaction. [13] [14]

If the card has not been promptly developed, the water content of the feces decreases, and this can reduce the detection of blood. [15] Although rehydration of stored samples can reverse this effect [16] this is not recommended because the test becomes unduly analytically sensitive and thus much less specific. [17] [18]

Some stool specimens have a high bile content that causes a green color to show after applying the developer drops. If entirely green, such samples are negative, but if questionably green to blue, such samples are designated positive. [19]

The package insert guidelines from the manufacturers, for example Hemoccult SENSA, [20] recommend that nonsteroidal anti-inflammatory drugs (NSAID), such as ibuprofen and aspirin, and iron supplements be discontinued for at least several days before the tests. There is a concern that these agents may irritate the body and cause biologically positive tests even in the absence of a more substantial illness, [21] [22] but there is some doubt about how frequently this occurs with NSAID medication. [23] [24] [25] Although both iron and bismuth containing products such as antacids and antidiarrheals can cause dark stools that are occasionally confused as containing blood, actual bleeding from iron is unusual. [26] [27]

There is no consensus on whether to stop warfarin before a guaiac test. [28] Even when using anticoagulants a high proportion of positive guaiac tests were found to be due to diagnosable lesions, suggesting anticoagulants may not cause bleeding unless there is an abnormality. [29] [30]

Clinical application

The article fecal occult blood (FOB) provides an expanded consideration of the clinical application of FOB tests generally, including other clinical methods, and the comments here are those that relate specifically to the guaiac gFOBT method.

One major use of stool testing for blood is detection of colorectal cancer. However, other possible positive results include: gastroesophageal cancer, GI bleeds, diverticulae, hemorrhoids, anal fissures, colon polyps, ulcerative colitis, Crohn's disease, celiac disease, GERD, esophagitis, peptic ulcers, gastritis, inflammatory bowel disease, vascular ectasias, portal hypertensive gastropathy, aortoenteric fistulas, hemobilia, endometriosis, and trauma.

The stool guaiac test was originally the principal colon cancer screening technology available, but modern tests which look for globin or DNA are now also available. Several recent colon cancer screening guidelines have recommended replacing any older low-sensitivity, guaiac-based fecal occult blood testing (gFOBT) with either newer high-sensitivity guaiac-based fecal occult blood testing (gFOBT) or fecal immunochemical testing (FIT), which tests for globin rather than the heme detected by the guaiac method. The US Multisociety Task Force (MSTF) looked at 6 studies that compared high sensitivity gFOBT (Hemoccult SENSA) to FIT, and concluded that there were no clear difference in overall performance between these methods, [31] and a similar recommendation was made by the National Guideline Clearinghouse (NGC). [32]

Results of a single fecal sample should be interpreted cautiously, as there is a high rate of false negativity associated with the test. [33] [10] Using three cards, each on a different day, is recommended to improve sensitivity. [34] The Centers for Disease Control and Prevention (CDC) in a 2006–2007 survey found extensive inappropriate use of low sensitivity gFOBT and of single specimens; it is unclear if these widespread suboptimal approaches have since declined. [35] The Current Procedural Terminology (CPT) coding was changed in January 2006 to include CPT code 82270, which indicates that consecutive collection of three stool samples has occurred, either as three single cards or a single triple card. Since January 2007, the US Medicare program reimburses for colorectal cancer screening with gFOBT only when this code is used. [36]

The stool guaiac test method may be preferable to fecal immunochemical testing (FIT) if there is a clinical concern about possible gastric or proximal upper intestinal bleeding. [37] However, although heme breakdown is less than globin during intestinal transit, false negative results can be seen with the stool guaiac tests due to degradation of the peroxidase-activity. This can cause false negative results in upper gastrointestinal bleeding sources, or in right colon adenomas and cancers that have comparable blood losses to positively testing left colon lesions. [38] A positive gFOBT with subsequent negative colonoscopy may lead to an upper endoscopy. [39] It is unclear whether this is an effective intervention if there is a positive gFOBT but no anemia. [40] [41] [42] Endoscopy when there is a positive gFOBT along with iron deficiency anemia, or iron deficiency anemia on its own, has a higher rate of finding problems.[ citation needed ]

Related Research Articles

<span class="mw-page-title-main">Colorectal cancer</span> Cancer of the colon or rectum

Colorectal cancer (CRC), also known as bowel cancer, colon cancer, or rectal cancer, is the development of cancer from the colon or rectum. Signs and symptoms may include blood in the stool, a change in bowel movements, weight loss, abdominal pain and fatigue. Most colorectal cancers are due to old age and lifestyle factors, with only a small number of cases due to underlying genetic disorders. Risk factors include diet, obesity, smoking, and lack of physical activity. Dietary factors that increase the risk include red meat, processed meat, and alcohol. Another risk factor is inflammatory bowel disease, which includes Crohn's disease and ulcerative colitis. Some of the inherited genetic disorders that can cause colorectal cancer include familial adenomatous polyposis and hereditary non-polyposis colon cancer; however, these represent less than 5% of cases. It typically starts as a benign tumor, often in the form of a polyp, which over time becomes cancerous.

<span class="mw-page-title-main">Colonoscopy</span> Examination of the bowel

Colonoscopy or coloscopy is a medical procedure involving the endoscopic examination of the large bowel (colon) and the distal portion of the small bowel. This examination is performed using either a CCD camera or a fiber optic camera, which is mounted on a flexible tube and passed through the anus.

<span class="mw-page-title-main">Upper gastrointestinal bleeding</span> Medical condition

Upper gastrointestinal bleeding (UGIB) is gastrointestinal bleeding in the upper gastrointestinal tract, commonly defined as bleeding arising from the esophagus, stomach, or duodenum. Blood may be observed in vomit or in altered form as black stool. Depending on the amount of the blood loss, symptoms may include shock.

<span class="mw-page-title-main">Rectal examination</span> Medical assessment or diagnostic procedure

Digital rectal examination (DRE), also known as a prostate exam, is an internal examination of the rectum performed by a healthcare provider.

<span class="mw-page-title-main">Fecal occult blood</span> Medical condition

Fecal occult blood (FOB) refers to blood in the feces that is not visibly apparent. A fecal occult blood test (FOBT) checks for hidden (occult) blood in the stool (feces).

<span class="mw-page-title-main">Angiodysplasia</span> Medical condition

In medicine (gastroenterology), angiodysplasia is a small vascular malformation of the gut. It is a common cause of otherwise unexplained gastrointestinal bleeding and anemia. Lesions are often multiple, and frequently involve the cecum or ascending colon, although they can occur at other places. Treatment may be with colonoscopic interventions, angiography and embolization, medication, or occasionally surgery.

<span class="mw-page-title-main">Diverticulosis</span> Condition of the wall of the intestine

Diverticulosis is the condition of having multiple pouches (diverticula) in the colon that are not inflamed. These are outpockets of the colonic mucosa and submucosa through weaknesses of muscle layers in the colon wall. Diverticula do not cause symptoms in most people. Diverticular disease occurs when diverticula become clinically inflamed, a condition known as diverticulitis.

<span class="mw-page-title-main">Gastrointestinal bleeding</span> Medical condition

Gastrointestinal bleeding, also called gastrointestinal hemorrhage (GIB), is all forms of bleeding in the gastrointestinal tract, from the mouth to the rectum. When there is significant blood loss over a short time, symptoms may include vomiting red blood, vomiting black blood, bloody stool, or black stool. Small amounts of bleeding over a long time may cause iron-deficiency anemia resulting in feeling tired or heart-related chest pain. Other symptoms may include abdominal pain, shortness of breath, pale skin, or passing out. Sometimes in those with small amounts of bleeding no symptoms may be present.

<span class="mw-page-title-main">Stool test</span> Medical examination of fecal matter

A stool test is a medical diagnostic technique that involves the collection and analysis of fecal matter. Microbial analysis (culturing), microscopy and chemical tests are among the tests performed on stool samples.

<span class="mw-page-title-main">Virtual colonoscopy</span> Medical imaging of the colon

Virtual colonoscopy is the use of CT scanning or magnetic resonance imaging (MRI) to produce two- and three-dimensional images of the colon, from the lowest part, the rectum, to the lower end of the small intestine, and to display the images on an electronic display device. The procedure is used to screen for colon cancer and polyps, and may detect diverticulosis. A virtual colonoscopy can provide 3D reconstructed endoluminal views of the bowel. VC provides a secondary benefit of revealing diseases or abnormalities outside the colon.

<span class="mw-page-title-main">Blood in stool</span> Medical condition

Blood in stool looks different depending on how early it enters the digestive tract—and thus how much digestive action it has been exposed to—and how much there is. The term can refer either to melena, with a black appearance, typically originating from upper gastrointestinal bleeding; or to hematochezia, with a red color, typically originating from lower gastrointestinal bleeding. Evaluation of the blood found in stool depends on its characteristics, in terms of color, quantity and other features, which can point to its source, however, more serious conditions can present with a mixed picture, or with the form of bleeding that is found in another section of the tract. The term "blood in stool" is usually only used to describe visible blood, and not fecal occult blood, which is found only after physical examination and chemical laboratory testing.

Rectal bleeding refers to bleeding in the rectum, thus a form of lower gastrointestinal bleeding. There are many causes of rectal hemorrhage, including inflamed hemorrhoids, rectal varices, proctitis, stercoral ulcers, and infections. Diagnosis is usually made by proctoscopy, which is an endoscopic test.

<span class="mw-page-title-main">Lower gastrointestinal bleeding</span> Medical condition

Lower gastrointestinal bleeding (LGIB) is any form of gastrointestinal bleeding in the lower gastrointestinal tract. LGIB is a common reason for seeking medical attention at a hospital's emergency department. LGIB accounts for 30–40% of all gastrointestinal bleeding and is less common than upper gastrointestinal bleeding (UGIB). It is estimated that UGIB accounts for 100–200 per 100,000 cases versus 20–27 per 100,000 cases for LGIB. Approximately 85% of lower gastrointestinal bleeding involves the large intestine, 10% are from bleeds that are actually upper gastrointestinal bleeds, and 3–5% involve the small intestine.

<span class="mw-page-title-main">Radiation proctitis</span> Medical condition

Radiation proctitis or radiation proctopathy is a condition characterized by damage to the rectum after exposure to x-rays or other ionizing radiation as a part of radiation therapy. Radiation proctopathy may occur as acute inflammation called "acute radiation proctitis" or with chronic changes characterized by radiation associated vascular ectasiae (RAVE) and chronic radiation proctopathy. Radiation proctitis most commonly occurs after pelvic radiation treatment for cancers such as cervical cancer, prostate cancer, bladder cancer, and rectal cancer. RAVE and chronic radiation proctopathy involves the lower intestine, primarily the sigmoid colon and the rectum, and was previously called chronic radiation proctitis, pelvic radiation disease and radiation enteropathy.

The Bristol stool scale is a diagnostic medical tool designed to classify the form of human faeces into seven categories. It is used in both clinical and experimental fields.

Tumor M2-PK is a synonym for the dimeric form of the pyruvate kinase isoenzyme type M2 (PKM2), a key enzyme within tumor metabolism. Tumor M2-PK can be elevated in many tumor types, rather than being an organ-specific tumor marker such as PSA. Increased stool (fecal) levels are being investigated as a method of screening for colorectal tumors, and EDTA plasma levels are undergoing testing for possible application in the follow-up of various cancers.

<span class="mw-page-title-main">Human feces</span> Metabolic waste of the human digestive system

Human feces are the solid or semisolid remains of food that could not be digested or absorbed in the small intestine of humans, but has been further broken down by bacteria in the large intestine. It also contains bacteria and a relatively small amount of metabolic waste products such as bacterially altered bilirubin, and the dead epithelial cells from the lining of the gut. It is discharged through the anus during a process called defecation.

<span class="mw-page-title-main">M2-PK Test</span> Screening for colorectal cancers and polyps

The M2-PK Test is a non-invasive screening method for the early detection of colorectal cancers and polyps which are known to be the precursors of colorectal cancer. The M2-PK Test which is used for stool analysis is available either as fully quantitative ELISA Test or as a rapid test that can be performed by any general practitioner without the need of a laboratory or any additional equipment.

A rectovaginal examination is a type of gynecological examination used to supplement a pelvic examination. In the rectovaginal examination, a doctor or other health care provider places one finger in the vagina and another in the rectum to assess the rectovaginal septum. The examiner will look for any scarring or masses that may indicate cancer or another disease. Typically, a rectovaginal examination is performed to assess pelvic pain, rectal symptoms, or a pelvic mass. It can also provide a sample for fecal occult blood testing.

<span class="mw-page-title-main">Fecal immunochemical test</span> Diagnostic test for colorectal cancer

Fecal Immunochemical Test (FIT) is a diagnostic technique that examines stool samples for traces of non-visible blood, which could potentially indicate conditions including bowel cancer. Symptoms which could be caused by bowel cancer and suggest a FIT include a change in bowel habit, anaemia, unexplained weight loss, and abdominal pain. By using a random forest classification model, sensitivity can be increased.

References

  1. ↑ "Guidance for Industry and FDA Staff — Review Criteria for Assessment of Qualitative Fecal Occult Blood In Vitro Diagnostic Devices". United States Food and Drug Administration Office of In Vitro Diagnostic Device Evaluation and Safety. August 8, 2007.
  2. ↑ "Fecal occult blood". www.fda.gov. Retrieved October 26, 2010.
  3. ↑ Rex DK, Johnson, DA, Anderson, JC, Schoenfeld, PS, Burke, CA, Inadomi, JM, American College of, Gastroenterology (Mar 2009). "American College of Gastroenterology guidelines for colorectal cancer screening 2009 [corrected]". The American Journal of Gastroenterology. 104 (3): 739–50. doi: 10.1038/ajg.2009.104 . PMID   19240699. S2CID   295873.
  4. ↑ Bretthauer M (August 2010). "Evidence for colorectal cancer screening". Best Pract Res Clin Anaesthesiol. 24 (4): 417–25. doi:10.1016/j.bpg.2010.06.005. PMID   20833346.
  5. ↑ Mandel JS, Bond JH, Church TR, et al. (1993). "Reducing mortality from colorectal cancer by screening for fecal occult blood". N Engl J Med. 328 (19): 1365–71. doi: 10.1056/nejm199305133281901 . PMID   8474513.
  6. ↑ Hardcastle JD, Chamberlain JO, Robinson MH, et al. (1996). "Randomised controlled trial of fecal occult blood screening for colorectal cancer". Lancet. 348 (9040): 1472–77. doi:10.1016/s0140-6736(96)03386-7. PMID   8942775. S2CID   11395104.
  7. ↑ Kronborg O, Fenger C, Olsen J, et al. (1996). "Randomised study of screening for colorectal cancer with fecal occult blood test". Lancet. 348 (9040): 1467–71. doi:10.1016/s0140-6736(96)03430-7. PMID   8942774. S2CID   37515050.
  8. ↑ Kewenter J, Brevinge H, Engaras B, et al. (1994). "Results of screening, rescreening and follow up in a prospective randomized study for detection of colorectal cancer by fecal occult-blood testing: results of 68,308 subjects". Scand J Gastroenterol. 29 (5): 468–73. doi:10.3109/00365529409096840. PMID   8036464.
  9. ↑ Beg M, et al. (2002). "Occult Gastrointestinal Bleeding: Detection, Interpretation, and Evaluation" (PDF). JIACM. 3 (2): 153–8. Archived from the original (PDF) on 2010-11-22. Retrieved 2010-10-26.
  10. 1 2 Collins JF, Lieberman DA, Durbin TE, Weiss DG (January 2005). "Accuracy of screening for fecal occult blood on a single stool sample obtained by digital rectal examination: a comparison with recommended sampling practice" (PDF). Annals of Internal Medicine. 142 (2): 81–5. CiteSeerX   10.1.1.580.829 . doi:10.7326/0003-4819-142-2-200501180-00006. PMID   15657155. S2CID   29833684.
  11. ↑ Kratochvil JF, et al. (1971). "Isolation and characterization of alpha-guaiaconic acid and the nature of guiacum blue". Phytochemistry. 10 (10): 2529–2531. Bibcode:1971PChem..10.2529K. doi:10.1016/s0031-9422(00)89901-x.
  12. ↑ Guthlein W, Wielinger H, Rittersdorf W, Werner W. "Guaiaconic acid A from guaiac resin, US Patent 4297271" (PDF). Free Patents Online.
  13. ↑ Jaffe RM, Kasten B, Young DS, MacLowry JD (December 1975). "False-negative stool occult blood tests caused by ingestion of ascorbic acid (vitamin C)". Annals of Internal Medicine. 83 (6): 824–6. doi:10.7326/0003-4819-83-6-824. PMID   1200528.
  14. ↑ Garrick DP, Close JR, McMurray W (October 1977). "Detection of occult blood in faeces". Lancet. 2 (8042): 820–1. doi:10.1016/S0140-6736(77)90753-X. PMID   71626. S2CID   5822559.
  15. ↑ Ahlquist DA, McGill DB, Schwartz S, Taylor WF, Owen RA (May 1985). "Fecal blood levels in health and disease. A study using HemoQuant". N. Engl. J. Med. 312 (22): 1422–8. doi:10.1056/NEJM198505303122204. PMID   3873009.
  16. ↑ Wells HJ, Pagano JF (1977). "Hemoccult test — reversal of false-negative results due to storage". Gastroenterology. 72: 1148.
  17. ↑ Macrae FA, St John DJ (May 1982). "Relationship between patterns of bleeding and Hemoccult sensitivity in patients with colorectal cancers or adenomas". Gastroenterology. 82 (5 Pt 1): 891–8. doi: 10.1016/S0016-5085(82)80252-7 . PMID   7060910.
  18. ↑ Frame PS, Kowulich BA (December 1982). "Stool occult blood screening for colorectal cancer". J Fam Pract. 15 (6): 1071–5. PMID   7142926.
  19. ↑ "Michigan Regional Laboratory System. Fecal occult blood". August 2007. Retrieved October 26, 2010.
  20. ↑ "None" (PDF).
  21. ↑ Grossman MI, Matsumoto KK, Lichter RJ (March 1961). "Fecal blood loss produced by oral and intravenous administration of various salicylates". Gastroenterology. 40 (3): 383–8. doi:10.1016/S0016-5085(61)80070-X. PMID   13709097.
  22. ↑ Pierson RN, Holt PR, Watson RM, Keating RP (August 1961). "Aspirin and gastrointestinal bleeding. Chromate blood loss studies". Am. J. Med. 31 (2): 259–65. doi:10.1016/0002-9343(61)90114-0. PMID   13735596.
  23. ↑ Norfleet RG (April 1983). "1,300 mg of aspirin daily does not cause positive fecal hemoccult tests". J. Clin. Gastroenterol. 5 (2): 123–5. doi:10.1097/00004836-198304000-00006. PMID   6304182.
  24. ↑ Doubilet P, Donowitz M, Pauker SG (1982). "Evaluation for colon cancer in patients with occult fecal blood loss while taking aspirin: a Bayesian viewpoint". Med Decis Making. 2 (2): 147–60. doi:10.1177/0272989x8200200206. PMID   7167043. S2CID   39268097.
  25. ↑ Bahrt KM, Korman LY, Nashel DJ (November 1984). "Significance of a positive test for occult blood in stools of patients taking anti-inflammatory drugs". Arch. Intern. Med. 144 (11): 2165–6. doi:10.1001/archinte.144.11.2165. PMID   6333854.
  26. ↑ Laine LA, Bentley E, Chandrasoma P (February 1988). "Effect of oral iron therapy on the upper gastrointestinal tract. A prospective evaluation". Dig. Dis. Sci. 33 (2): 172–7. doi:10.1007/BF01535729. PMID   3257437. S2CID   10139402.
  27. ↑ Anderson GD, Yuellig TR, Krone RE (May 1990). "An investigation into the effects of oral iron supplementation on in vivo Hemoccult stool testing". Am. J. Gastroenterol. 85 (5): 558–61. PMID   2186616.
  28. ↑ Imperiale TF (September 2010). "Continue or discontinue warfarin for fecal occult blood testing in 2010? Does the published evidence provide an answer?". Am. J. Gastroenterol. 105 (9): 2036–9. doi:10.1038/ajg.2010.269. PMID   20818354. S2CID   22003870.
  29. ↑ Jaffin BW, Bliss CM, LaMont JT (August 1987). "Significance of occult gastrointestinal bleeding during anticoagulation therapy". Am. J. Med. 83 (2): 269–72. doi:10.1016/0002-9343(87)90697-8. PMID   3497580.
  30. ↑ Barada K, Abdul-Baki H, El Hajj II, Hashash JG, Green PH (January 2009). "Gastrointestinal bleeding in the setting of anticoagulation and antiplatelet therapy". J. Clin. Gastroenterol. 43 (1): 5–12. doi:10.1097/MCG.0b013e31811edd13. PMID   18607297. S2CID   25371088.
  31. ↑ Levin B, Lieberman DA, McFarland B, et al. (May 2008). "Screening and surveillance for the early detection of colorectal cancer and adenomatous polyps, 2008: a joint guideline from the American Cancer Society, the US Multi-Society Task Force on Colorectal Cancer, and the American College of Radiology". Gastroenterology. 134 (5): 1570–95. doi: 10.1053/j.gastro.2008.02.002 . PMID   18384785. Also published as Levin B, Lieberman DA, McFarland B, et al. (2008). "Screening and surveillance for the early detection of colorectal cancer and adenomatous polyps, 2008: a joint guideline from the American Cancer Society, the US Multi-Society Task Force on Colorectal Cancer, and the American College of Radiology". CA Cancer J Clin. 58 (3): 130–60. doi: 10.3322/CA.2007.0018 . PMID   18322143. S2CID   8199010.
  32. ↑ "National Guideline Clearinghouse | Colorectal cancer screening clinic…". archive.ph. August 2, 2012.
  33. ↑ "Archived copy" (PDF). Archived from the original (PDF) on 2010-11-21. Retrieved 2010-07-18.{{cite web}}: CS1 maint: archived copy as title (link)
  34. ↑ "Screening average risk patients for colorectal cancer — B01" . Retrieved 2007-10-25.
  35. ↑ Nadel MR, Berkowitz Z, Klabunde CN, Smith RA, Coughlin SS, White MC (August 2010). "Fecal occult blood testing beliefs and practices of U.S. primary care physicians: serious deviations from evidence-based recommendations". J Gen Intern Med. 25 (8): 833–9. doi:10.1007/s11606-010-1328-7. PMC   2896587 . PMID   20383599.
  36. ↑ Centers for Medicare and Medicaid Services. Colorectal cancer: Preventable, treatable and beatable: Medicare coverage and billing for colorectal cancer screening. Medicare Learning Network Matters SE0710. www.cms.hhs.gov/MLNMattersArticles/downloads/SE0710.pdf Accessioned 2010 November 1
  37. ↑ Rockey DC (July 1999). "Occult gastrointestinal bleeding". N. Engl. J. Med. 341 (1): 38–46. doi:10.1056/NEJM199907013410107. PMID   10387941.
  38. ↑ Herzog P, Holtermüller KH, Preiss J, et al. (November 1982). "Fecal blood loss in patients with colonic polyps: a comparison of measurements with 51chromium-labeled erythrocytes and with the Haemoccult test". Gastroenterology. 83 (5): 957–62. doi: 10.1016/S0016-5085(82)80061-9 . PMID   7117808.
  39. ↑ Rockey DC (December 2005). "Occult gastrointestinal bleeding". Gastroenterol. Clin. North Am. 34 (4): 699–718. doi:10.1016/j.gtc.2005.08.010. PMID   16303578.
  40. ↑ Zappa M, Visioli CB, Ciatto S, et al. (April 2007). "Gastric cancer after positive screening faecal occult blood testing and negative assessment". Dig Liver Dis. 39 (4): 321–6. doi:10.1016/j.dld.2006.11.010. PMID   17314076.
  41. ↑ Bond JH (April 2007). "FOBT is not an effective way to screen for gastric cancer". Dig Liver Dis. 39 (4): 327–8. doi:10.1016/j.dld.2006.12.013. PMID   17317346.
  42. ↑ Allard J, Cosby R, Del Giudice ME, Irvine EJ, Morgan D, Tinmouth J (February 2010). "Gastroscopy following a positive fecal occult blood test and negative colonoscopy: systematic review and guideline". Can. J. Gastroenterol. 24 (2): 113–20. doi: 10.1155/2010/516363 . PMC   2852233 . PMID   20151070.
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.