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Influence of diet on occult blood tests
... Chemical fecal occult bold tests are not specific for human blood [7]. In condition of dietary constituent with sufficient peroxidase activity they may give false positive results [19]. On the other hand various chemicals may interfere with the test and lead to providing false negative results [20,21]. ...
... D. G. Illingworth [6] As this 1 ml. of blood was contained in the daily stool it is evident that the tests are capable of detecting bleeding into the stomach of the order of 1 ml. in 24 hours. ...
Intestinal parasitic infections are common worldwide. This infection is closely related to poor socio economic status, hygiene, and overcrowding, contaminated food and water. The parasitic infection may remain asymptomatic and give rise to bleeding which may go unnoticed. The relationship between parasitic infections has adverse effect on the hemoglobin and thereby the nutritional status of the human host is well established. Total 300 stool samples attending tertiary care centre were screened for intestinal parasitic infection and fecal occult blood. To compare the positive results of intestinal parasitic infected individual with fecal occult blood. All the samples were screened for detecting the intestinal parasites. The fecal occult blood was detected by Benzidine test. In 300 patients there were 171 males, 129 female patients. 163 were children and 137 were adults. Our study showed 188 (63%) positivity for parasitic infection which was very high. These positive samples were also tested for occult blood which was fruitful in 154 cases. This occult blood detection gave more sensitive result, by yielding 51% positive response. This study showed a high positivity of intestinal parasitic infections with positive fecal occult blood. Therefore fecal occult blood detection is a must along with the screening for parasitic ova/ cyst in hospital, especially in asymptomatic patients. This paves the path for effective and efficient management of the infested and anemic patients.
... Caused by peroxidases that act like haemoglobin and give false positives. Cooking for 20 mins at 100°C destroys peroxidases and a delay of 2 days between collection and analysis is also effective as long as a non-hydrated gFOBT is used [53,110] Negative interference Comment Reference ...
Multidisciplinary, evidence-based guidelines for quality assurance in colorectal cancer screening and diagnosis have been developed by experts in a project coordinated by the International Agency for Research on Cancer. The full guideline document covers the entire process of population-based screening. It consists of 10 chapters and over 250 recommendations, graded according to the strength of the recommendation and the supporting evidence. The 450-page guidelines and the extensive evidence base have been published by the European Commission. The chapter on faecal occult blood testing includes 21 graded recommendations. The content of the chapter is presented here to promote international discussion and collaboration by making the principles and standards recommended in the new EU Guidelines known to a wider professional and scientific community. Following these recommendations has the potential to enhance the control of colorectal cancer through improvement in the quality and effectiveness of screening programmes and services.
Colorectal cancer has long been the target of efforts aimed at early detection. It is the second most common cancer in the United States, with 140,000 new cases and 60,000 deaths estimated to have occurred in 1987.1 Uncommon in individuals under 50, its incidence increases sharply thereafter.2 Investigations into the causes of colorectal cancer have not yet yielded a consensus strategy for prevention. However, early treatment is generally acknowledged to be more beneficial than late treatment. Early detection thus seems to be a reasonable approach to lowering the toll of this cancer.
Abstract Only a fraction of haem (ferroprotoporphyrin) finding its way into the gut lumen is absorbed; the major portion enters the colon. There, unabsorbed haem, together with any haem of haemoproteins shed directly into the colonic lumen as haemoglobin or other haemoproteins, are converted by bacteria to a range of haem-derived porphyrins (HDP) lacking iron. This conversion is a slow and incomplete process and the amount converted in this way depends on colonic transit rate, site of bleeding and amount of luminal haem. As a consequence, faeces contain variable proportions of haem and HDP. The guaiac and tetramethylbenzidine tests give a qualitative index of faecal blood; they depend on the pseudoperoxidase activity of intact haem and cannot detect HDP. These tests perform better for large bowel bleeding than for more proximal bleeding. The fluorimetric HemoQuant assay quantitates both haem and HDP; it performs well for both proximal and distal bleeding. Neither type of test can allow for intestinal absorption of haem or HDP. Quantitation of gastrointestinal bleeding derived from measurement of faecally excreted haem and HDP is, therefore, likely to underestimate haem delivered into the gut lumen. In a given clinical situation, the choice of a haem-dependent occult blood test must take into account the possibility of colonic conversion of haem to HDP and the possible value of quantitation as opposed to qualitative detection.
Colorectal cancer is a common and devastating disease. Many authorities recommend screening asymptomatic person, although the benefit of such screening is without scientific validation. Each of the screening modalities available has been examined, and their merits and shortcomings have been discussed.
Surveys have indicated that primary care physicians generally agree with screening asymptomatic patients, but only a minority actually comply with the recommendations. Patient acceptance also varies. Thus, while specialty boards and panels of experts attempt to arrive at policies for the general population, primary care physicians must interact with the individual patient.
Until data from ongoing prospective screening studies are available and cost-benefit issues are resolved, screening for colorectal cancer will remain at the discretion of physicians and their patients. There is insufficient evidence to support either continuing or discontinuing the recommended examinations for asymptomatic patients. The screening examinations can be recommended on the basis of a theoretical benefit, however. They can be performed with a minimum of risk of injury or side effects. Certain patients can be identified as being at above-average risk and deserving of more consideration. If aware of the benefits and limitations of colorectal cancer screening, primary care physicians can decide how to implement colorectal cancer screening in their clinical practice.
Monoclonal antibodies to human hemoglobin were produced and a colloidal gold agglutination method has been developed for detection of fecal occult blood. Since hemoglobin is composed of the tetramer, alpha 2 beta 2, a single monoclonal antibody-labeled colloidal gold can agglutinate with hemoglobin. The lowest detectable hemoglobin concentration was 0.5 micrograms/ml. A total of 785 fecal samples were determined using colloidal gold agglutination and compared with latex agglutination. The colloidal gold agglutination detected blood in 75 samples, whereas latex agglutination detected blood in 76 samples, and among them 70 were positive in both methods. Overall agreement between the two methods was 98%.
A pilot study was undertaken to find out whether faecal haemoglobin, albumin and alpha-1-antitrypsin from patients with gastrointestinal disorders could distinguish active bleeders from non-active bleeders and healthy volunteers. Alpha-1-antitrypsin is not as readily degraded by endogenous and bacterial breakdown as haemoglobin and albumin and consequently could be a better marker for occult bleeding.
This study examines three faecal occult blood tests, Haemoccult, Fecatwin and E-Z Detect, each with different sensitivities, to determine which is best suited for use in symptomatic patients--both for the detection of cancer and of non-malignant mucosal disease of the large bowel. A test was completed by 1025 patients before double-contrast barium enema and the performance of each test was determined from the result of this investigation. The study was completed by 969 patients. There were 49 patients with colorectal cancer, 92 patients with a cancer or a polyp greater than 5 mm, and 130 with some mucosal abnormality. The test most sensitive for blood, Fecatwin, detected 14 of 15 (93 per cent) cancers and 29 (69 per cent) of 42 patients with mucosal disease (including inflammatory bowel disease) but gave three times as many false positive results as the Haemoccult test, which is less sensitive for blood. The chance of a patient with a positive Haemoccult result having mucosal disease on barium enema was 24 of 47 patients (51 per cent) (two-thirds of these having colorectal cancer). A negative Haemoccult result, however, was unreliable and should not influence patient management. A test less sensitive for blood than Haemoccult was found to be of little value in symptomatic patients.
Colorectal cancer is a common disease with a high mortality rate. Surgical resection in early stages is the only effective treatment, therefore, recent attention is focused on diagnosing early colon cancer by screening asymptomatic subjects. Principles and current technology supporting early detection of colorectal cancer are critically evaluated. Current guidelines for screening average risk asymptomatic subjects and high-risk groups are discussed.
The assumption that asymptomatic colorectal cancers bleed provides the rationale for widespread stool screening. The authors studied 12 patients with unoperated colorectal cancer but without colorectal symptoms and six healthy volunteers as laboratory controls. All stools were collected for 2 weeks and analyzed by the HemoQuant and Hemoccult tests. In controls, the mean HemoQuant value was 0.7 mg hemoglobin (Hb)/g stool (range, 0.1-1.8) and all stools were Hemoccult-negative. In cancer patients, the mean HemoQuant was 3.3 mg Hb/g (range, 0.3-13.2); stools were within the normal HemoQuant range (less than 2 mg Hb/g) in 38% and negative by Hemoccult in 70%. The mean cancer detection rate testing a single stool per patient was 57% for HemoQuant and 25% for Hemoccult (P less than 0.001). The detection rate rose testing multiple stools and was maximal with five stools at 83% for HemoQuant compared to 31% for Hemoccult (P less than 0.001). The authors conclude that fecal blood levels are commonly normal with asymptomatic colorectal cancer. Although higher with HemoQuant than Hemoccult, cancer detection rates by fecal blood testing appear to be lower than previously reported.
Testing feces for occult blood is widely recommended as a means of detecting subclinical colorectal tumors. Guaiac tests such as Hemoccult® are the most widely used, but chemical sensitivity is relatively low and the tests are affected by dietary peroxidases, the state of fecal hydration, and certain drugs. The newly devised HemoQuant® and immunologic techniques appear more sensitive and specific, but they require further evaluation before widespread clinical usage can be recommended.
Occult blood screening has both merits and weaknesses. Testing does uncover subclinical colorectal cancer, often at a relatively early stage, but whether this actually improves the prognosis remains to be proven. Benign neoplastic polyps are also detected, although it is debatable whether this is a valid rationale for screening. Test sensitivity for malignancy varies from good to moderate, but is poor for benign polyps. Specificity is usually around 97%–98%, yet the predictive value of a positive test for cancer is only about 10%: hence most test-positive individuals are needlessly subjected to invasive colonic investigations. Reported figures on public compliance with occult blood testing vary widely from excellent to poor. Published costs of screening are usually quite low, but these overlook important indirect and hidden expenses and are therefore misleading.
On balance, the problems of occult blood testing currently appear to outweight the merits. This could change, however, with the newer testing techniques and with awaited mortality data from controlled clinical trials now underway.
We sought to determine the short-term effects of use of aspirin and ethanol on fecal occult blood levels measured with the HemoQuant assay. A factorial design was used to study 68 healthy volunteers randomized to receive various doses of aspirin, ethanol, or a combination of both for either 1 or 3 days. Fecal hemoglobin concentrations were measured before and after drug ingestions. Moderate quantities of ethanol (300 ml of 5% or 30 ml of 50% three times nightly) did not cause significant fecal blood elevation unless aspirin was administered concomitantly (P = 0.05). High-dose aspirin alone, 975 mg three times daily, induced abnormal blood loss (P less than 0.01). The highest HemoQuant levels were usually noted after concomitant administration of aspirin and ethanol at maximal doses for 3 days (P less than 0.005), some HemoQuant levels approaching 5 times the normal value. We conclude that, in a short-term analysis, social consumption of ethanol is unlikely to interfere with fecal blood testing but therapeutic doses of aspirin will.
The author reviews the literature on occult blood surveillance for colorectal carcinoma. The guaiac-based Hemoccult (SmithKline Diagnostics, Sunnyvale, Calif.) test is the most reliable and widely used. However, testing is complicated by several technical issues that can affect clinical results, and even successful screening programs will miss a high proportion of tumors. Public compliance is often poor, and a number of indirect and "hidden" costs make surveillance programs much more expensive than is usually claimed. Almost all published screening trials are uncontrolled. They generally detect about 3-20 colorectal malignancies for every 10,000 people enrolled, but only about 5%-10% of occult blood reactions are due to cancer. Though screen-detected tumors tend to be at a relatively early stage, this does not imply any benefit of surveillance because of lead time and length biases inherent in the screening process. Only controlled trials can answer the central question of whether screening decreases mortality from bowel cancer. Two such trials are underway, but mortality data are not yet available from either.
A versatile, qualitative, agarose gel immunoprecipitation (IP) test for the detection of fecal occult hemoglobin (Hb) was developed to provide a more accurate method for the detection of occult blood in stool. This test allowed detection of 0.2 mg human hemoglobin/g of stool after a 2-h incubation. In addition, a specimen application device which can accommodate a variety of specimens was developed for this test. A study of 252 clinical stool specimens revealed a close correlation in the results obtained at three separate laboratories. The IP test identified blood in 11 out of 24 specimens collected from patients with colorectal carcinoma as compared to 4 of 24 specimens positive with a guaiac-based Hemoccult II test. The simplicity of immunoprecipitation coupled with the high sensitivity and specificity of this technique suggests that this new test would be a very useful and effective means with which to screen for occult blood in stool.
In 20 healthy volunteers ingesting 5 to 50 ml of51Cr-red cells, reaction intensities obtained with four chemical methods for fecal occult blood were compared with the “true” blood loss simultaneously determined by radioassay of each stool. Dilute tincture of guaiac reagent was found to have the same sensitivity and high frequency of false-positive reactions as the saturated guaiac reagent, but was more reproducible. HematestTM was slightly less sensitive but was poorly reproducible and yielded frequent false-negative as well as false-positive reactions. False-positive reactions by both methods were not eliminated by a meat-free diet; they were increased with guaiac reagents if stools were stored for 3 or more days. A new guaiac method (HemoccultTM) was found to be one-fourth as sensitive as the older tests, but was virtually free from false-positive reactions, even on an unrestricted diet and after storage of the stool specimens. It is recommended that the use of Hematest be abandoned and that Hemoccult be used preferentially if future studies confirm that its sensitivity is sufficient to detect most gastrointestinal lesions which are yielding occult blood.
Iron absorption is under delicate control and the level of absorption is adjusted to comply with the body's need for iron. To measure the intestinal setting for iron absorption, and thereby indirectly assess body iron requirements, cobaltous chloride labelled with (57)Co or (60)Co was given by mouth and the percentage of the test dose excreted in the urine in 24 hours was measured in a gamma counter. Seventeen control subjects with normal iron stores excreted 18% (9-23%) of the dose. Increased excretion, 31% (23-42%), was found in 10 patients with iron deficiency anemia and in 15 patients with depleted iron stores in the absence of anemia. In contrast, 12 patients with anemia due to causes other than iron deficiency excreted amounts of radiocobalt within the normal control range. In patients with iron deficiency, replenishment of iron stores by either oral or parenteral iron caused the previously high results to return to normal.Excretion of the test dose was normal in portal cirrhosis with normal iron stores but it was markedly increased in patients with cirrhosis complicated by either iron deficiency or endogenous iron overload. It was also raised in primary hemochromatosis. Excretion of the dose was reduced in gluten-sensitive enteropathy. Gastrointestinal surgery and inflammatory disease of the lower small intestine had no effect on the results except that some patients with steatorrhea had diminished excretion.The cobalt excretion test provides the clinician with a tool for the assessment of iron absorption, the detection of a reduction in body iron stores below the level that is normal for the subject in question, the differentiation of iron deficiency anemia from anemia due to other causes, and the investigation of patients with iron-loading disorders.
A new two-phase test kit for faecal occult blood combining a sensitive guaiac test (Fecatwin (S)ensitive) with an immunological test for human haemoglobin (FECA-EIA) was compared with three current guaiac tests (Fecatest, Fecatwin, Haemoccult) in 19 colorectal cancer patients and 11 controls on a restricted diet. A total of 43 48 h faecal samples (30 from cancer patients and 13 from controls) were collected for quantitative determination of faecal blood loss with the 51Cr method. Qualitative testing revealed that FECA-EIA was the most sensitive test, giving one (3%) false negative test result in the 30 tests on colorectal cancer patients and no false positives in the control subjects. It was also the only test that detected low-degree tumour bleeding. Fecatest and Fecatwin S were the most sensitive guaiac tests, giving 7 and 10% false negative test results, respectively, in the 30 colorectal cancer samples, whereas Haemoccult and Fecatwin gave 23% false negative test results. For screening purposes and in order to reduce costs it is suggested that only the positive test results of the very sensitive guaiac test (Fecatwin S) should be tested with the FECA-EIA test to eliminate false positive results. With this approach the diagnostic accuracy of the new two-phase test will be about twice as good as for the Haemoccult test.
Over a 3.5 year period beginning September 1978, we gave fecal occult blood test kits to 13,522 outpatient applicants for medical care. Two thousand nine hundred sixty-four (22 percent) kits were returned completed according to instructions. One or more specimens were positive in 135 (5 percent) of the tests returned. One hundred twenty of the 135 patients with positive results were investigated by history, physical examination, digital rectal examination, and colonoscopy. Seventy-six of the 120 also had double-contrast barium enemas. Fifty-nine (48 percent) of the 120 patients who completed the work-up had neoplastic lesions; 14 of them were malignant (11.4 percent) and 44 were benign (36.6 percent). Three of the malignant lesions were carcinoma in situ, three had stalk invasion but no residual tumor was found at surgery (Dukes' type A), four were Dukes' type B, and three were Dukes' type C. The classification of one was uncertain. There was stalk invasion, but no further surgery was performed. Thus, of the 14 malignant lesions detected during the first screening, 13 had known classifications and 10 of these 13 were therapeutically favorable (carcinoma in situ, Dukes' type A or B). Ten of the 14 malignant lesions were beyond the range of the rigid proctosigmoidoscope. Our results to date indicate the following: (1) There was excellent patient follow-up and compliance for diagnostic procedures and therapeutic intervention (88.8 percent) when the results of the fecal occult blood test were positive. (2) Neoplasia had a high predictive value (48 percent). (3) A favorable staging for malignant lesions was detected by this method (71 percent). (4) An unacceptably high percentage of malignant lesions were beyond the range of the rigid sigmoidoscope (71 percent). (5) Work-up for patients with a positive fecal occult blood test result should include full colonoscopic examination.
An immunochemical test for fecal occult blood was developed for use in colon cancer screening. The test employs high titer monospecific antisera to intact human hemoglobin in a radial immunodiffusion assay. Patient smears on specially treated filter paper allow screening procedures similar to those using Hemoccult slides. Minimum detectible hemoglobin was 0.3 mg/gm stool, and no cross reactivity with dietary constituents, drugs, or chemicals occurred. The accession of 150 consecutive cases of colon-rectal carcinoma was accomplished from three community hospitals. In each instance, at least one preoperative fecal specimen was obtained for companion smear testing with immunochemical punch-disc and commercial Hemoccult slides. Twenty-nine percent of the cases were found not to be bleeding by either test. Occult bleeding was detected by Hemoccult in 40% of the cases, and occult bleeding was detected by immunochemical testing in 65% of the cases. A surprising discovery was that rectal lesions had a much lower rate of of positiuity with both tests (Hemoccult-29%, Immunochemical-50%) than other locations. These results suggest that immunochemical screening for occult blood loss will provide a higher rate of detection of colon cancer.
The peroxidase content of aqueous extracts of a variety of fresh foods was measured by spectrophotometry and expressed in relation to the pseudoperoxidase activity of blood. A wide range of activities was found in extracts from different foods but inter sample and inter seasonal variation for any single food was of no practical significance. The results may be used to design diets suitable for colorectal cancer screening programs that use peroxidase-dependent fecal occult blood tests. Am J Clin Nutr 1982;35:l487-l489.
This literature review explores: the purposes and mechanics of fecal occult blood testing; the relative sensitivity to hemoglobin of various test methods; the effects of extrinsic agents (diet, drugs, vitamin C) on the validity of the tests; and the effects of storage and delayed development of specimens on the reliability of the tests. Discussion is concluded with a summary of the highlights from the literature and a recommended guideline for the use of fecal occult blood tests.
Six dogs were fed each of nine diets to evaluate the effects of diet on fecal occult blood test results. The diets represented a range of different type (i.e. canned, dry or semi-moist), protein and vegetable constituents, and fiber contents. Each diet was fed twice daily for five consecutive days; fecal samples were collected twice daily on days 4 and 5. An o-tolidine test kit and a guaiac paper test kit for fecal occult blood were used. Two hundred and sixteen fecal samples were analyzed (24 samples/diet). When using the guaiac test the following positive results were obtained from fecal samples from dogs consuming a canned meat- and vegetable-based diet (24/24 samples); a canned meat-based diet (24/24 samples); a dry corn and poultry-based diet (9/24 samples); a dry corn, wheat, and meat meal diet (4/24 samples), a canned poultry-based diet (1/24 sample) and a semi-moist soybean meal-based diet (2/24 samples). A total of 64 samples were positive using the guaiac test. Using the o-tolidine test, no samples were positive. The difference between the number of positive results with each test kit was highly significant (p < 0.001). Results indicate that 1) diet affects the specificity of guaiac test fecal occult blood results in the dog and 2) positive o-tolidine test results were not caused by diets fed in the study.
Alpha 1-antitrypsin was measured in 5-day faecal collections from patients with colorectal cancer or adenomatous polyps and a symptomatic control group. Collections were homogenized and lyophilized prior to measurement of alpha 1-antitrypsin by radial immuno-diffusion. Colorectal cancer dry weight concentrations were significantly higher than the symptomatic control results, with 57% having results greater than 95% normal values of this control group. There was no significant difference between adenomatous polyp dry weight concentrations and symptomatic control results. Wet weight concentrations were calculated from wet/dry ratios. Colorectal cancer wet weight concentrations were significantly higher than symptomatic control results with 48% having results greater than 95% normal values of this control group. Alpha 1-antitrypsin was also measured in non-lyophilized samples from an asymptomatic control group (n = 39). Colorectal cancer wet weight concentrations were significantly higher than asymptomatic control results, with 62% having results greater than 95% normal values of this control group. Faecal alpha 1-antitrypsin measurement deserves further assessment for use in detecting colorectal cancer.
Colorectal cancer (CRC) is the second most common form of malignancy, causing death after late presentation in two-thirds of cases. Early detection makes curative treatment likely. Faecal occult blood tests (FOBTs) detect some pre-symptomatic CRCs and their precursor lesions, adenomatous polyps. A trial showed reduced mortality in USA volunteers aged 50-80 with regular FOBTs; both this and the Nottingham population-based trial detected earlier-stage CRCs. Current US guidelines recommend annual digital rectal examination and FOBTs from age 40. FOBTs have been included in the USAF examination of aircrew for several years. Day-case colonoscopy, with appropriate biopsy-excision, is the first-choice follow-up investigation. This study aims to investigate the design of any programme to introduce FOBTs as part of the RAF's existing schedule of Periodic Medical Examinations (PMEs) and Screenings, and the age groups to be included, rather than the decision as to whether or not it should be commenced. The analysis therefore examines the cost per cancer detected. The information required to evaluate subsequent outcomes, such as cost per life-year saved, is not available for the RAF population so speculative extrapolation from other data is not attempted. Over a third of RAF personnel are under the age of 25, nearly three-quarters under 35 and over four-fifths under 40. Over a quarter of the 4 RAF CRC cases pa occur under age 40 and two-thirds under 50. The most cost-effective age at which to introduce FOBTs in the RAF is 40, regardless of the following parameters. Assuming FOBT sensitivity of 55% and positivity 5%, FOBT costing 23p and colonoscopy 175 pounds, starting FOBTs RAF-wide at age 40 would cost annually 35,968 pounds and 15,881 pounds per CRC case detected. The FOBT contribution to the costs is extremely small and the importance of maximising sensitivity and specificity very great. Hence dietary modification, and using a test or combination of tests with higher sensitivity and/or lower false-positivity, even if much more expensive, would be highly cost-effective, reducing the above costs substantially. Counting as "cases" persons with adenomas reduces the cost per "case" detected by about 75%. A pilot study is proposed concerning the introduction on selected stations of FOBTs with RAF PMEs/Screenings, from age 40, to determine: sensitivity and false-positivity rates for single and serial FOBTs, and the predictive value of positive tests, in RAF screenees; the annual cost; the costs per CRC case, and per CRC-plus-adenoma case, detected; possibly, an estimate of the cost per life-year saved; and, hence, whether the programme should be extended to all RAF personnel. FOB screening from age 40 would miss the quarter of RAF CRC cases which occur in personnel under 40. Identification is therefore recommended now of personnel at high risk for CRC, because of personal or family history, at all PMEs/Screenings, regardless of age, with the subsequent offer of serial FOBTs annually and regular colonoscopy. 2 1/2 yearly [corrected] FOBTs, done with PMEs/Screenings and half-way through the 5 year interval, would detect almost as many CRCs as annual testing, missing only half as many as 5-yearly testing. This analysis provides information on the costs and consequences of various FOB screening strategies for the RAF and other Services. Similar principles can be applied to develop informed strategies for other screening.
There are relatively few established etiologic factors for colorectal cancer, and therefore primary prevention remains speculative. Diet has been most widely studied, and results indicate that diets high in fat, meat, and protein are positively associated with colorectal cancer, whereas diets high in vegetables, fruits, and fibers are negatively associated [1]. Intervention studies have yet to show that modifying diets will alter risk.
Fecal blood is an inherently insensitive and nonspecific marker for asymptomatic colorectal neoplasia. As such, use of fecal occult blood tests (FOBTs) necessarily limits the effectiveness and efficiency of a screening application. FOBT screening may result in a modest reduction in colorectal cancer-specific mortality, but it alters neither colorectal cancer incidence nor overall mortality. Costs resulting from FOBT screening are substantial, and the extent to which screen-induced mortality offsets any benefits remains unknown. In the absence of a clearly demonstrated net benefit with FOBT screening, affordability of this expensive effort can be legitimately questioned.
Colorectal cancer occurs throughout the world. Little is known about the etiology of this disease, however, adequate data exist to recommend secondary prevention with mass screening of average risk asymptomatic people age 50 or over. Three randomized controlled trials of a guaiac test for fecal occult blood involving over 250,000 participants found significant reductions in colorectal cancer mortality from both annual and biennial screening. Results from observational studies are consistent with the results from the randomized trials. Therefore, a screening recommendation for a fecal occult blood testing can be justified based on the overwhelming scientific evidence. A compelling argument can be made to use an immunochemical rather than guaiac test, since data suggests that immunochemical tests may be more sensitive and more specific than guaiac tests. Colorectal cancer mortality reductions of at least 33% can be attained with annual fecal occult blood testing. Biennial screening will result in reductions of at least 15 to 20%. There is insufficient evidence to justify either flexible sigmoidoscopy or colonoscopy for mass screening of an average-risk asymptotic population. However, there is justification for colonoscopic evaluation of high-risk members of the population.
It has recently been suggested that in adults with coeliac disease, faecal blood loss may play a role in the development of iron deficiency. A group of 45 children diagnosed with coeliac disease during 1996 and 1997 were therefore prospectively evaluated for the presence of gluten in their diet, iron deficiency anaemia, and faecal occult blood. Sixty children admitted for elective surgery or asthma served as controls. Faecal occult blood was found in four iron deficient children on normal diet, of whom three were newly diagnosed. Occult blood loss disappeared in three of the four children when gluten was removed from their diet. Faecal occult blood was found in 26.7% of children on gluten-containing diet, but not in children on gluten-free diet (P=0.01), or in control children (P=0.001).
Conclusion Our data suggest that the incidence of occult blood loss in coeliac disease occurs mainly in newly diagnosed cases and responds to a gluten-free diet. Occult blood testing may not be warranted in the absence of iron deficiency anaemia nor in children with iron deficiency anaemia who are on a gluten-free diet.
Background:
Detection of blood in feces or urine has long been regarded as an indicator of patient's state of health. The ease with which feces or urine may be obtained and patient's willingness to provide the specimen make detection of fecal occult blood or urine analysis one of the most commonly performed screening examinations. Historically, the inspection of feces or urine for diagnostic purpose has been practiced for centuries. Of late, management of renal or urinary tract abnormalities or investigation of anemia, gastrointestinal diseases and for early detection of colorectal cancer has assumed greater importance.
Methods:
The never-ending list of techniques for the diagnosis of disorders producing bleeding such as urine microscopy, urine cytology, urine based marker test, cytoscopy, ultra sonography, computed tomography, magnetic resonance imaging, to mention a few, and four categories of detection of fecal occult blood namely, radioanalytical, physical, immunochemical and chemical methods makes the study very interesting.
Purpose:
This review attempts to overview various techniques, methods and methodologies for the diagnosis and detection of blood in feces and urine, in the direction of looking at past and current tests with an eye on future needs.
Animal experiments and limited number of human investigations in addition to clinical experiences suggested that gastrointestinal motility is inhibited during pregnancy due to metabolic and hormonal changes. Particularly the higher level of progesterone mediates this inhibitory effect inducing several digestive symptoms and diseases (Scott and Abu-Hamada, 2004).
Death from malignant diseases now holds the second position as a destroyer of human life in America. Most physicians have had the disquieting experience of making the diagnosis of malignant disease too late to be able to offer any effective treatment. Our great hope for the future lies in the discovery of some agent that will destroy malignant tissue wherever it exists or perhaps will even prevent the very inception of malignant disease. Until the day when such an agent becomes a practical actuality, we must content ourselves with the use of the tools at hand.A nation-wide campaign is under way to educate the public in the early detection of cancer. It therefore behooves us as physicians to reexamine and to use every practical means available to detect the presence of cancer in its early phases. The American Cancer Society and the National Cancer Institute have found that cancer
A 50-year survival of a textbook is rather remarkable in contemporary medicine. The record probably belongs to Hippocrates, whose works were useful in clinical medicine for more than two millennia. The first edition of French's Differential Diagnosis was published in 1912. It was designed to cover the "whole ground of medicine, surgery, gynecology, ophthalmology, dermatology, and neurology." Arthur H. Douthwaite is the senior editor of the eighth edition, which follows the traditional format. I owned and used one of the interim editions for a number of years. It was a valuable reference work. I question whether I reached a specific conclusion on the basis of reference to this volume on any diagnosis of a difficult nature. I am sure that it contributed, however, in a number of instances. Since current diagnosis requires a tremendous amount of data supplementary to signs and symptoms, such a volume probably contributes less to the
The finding of occult blood in the feces, when hemorrhage from the nose, mouth, throat, esophagus and hemorrhoids can be eliminated, is of the highest importance in the diagnosis of ulceration of the digestive tract. In conjunction with certain clinical symptoms, occult blood may be looked on as pathognomonic of ulcerating lesions of the stomach or the intestine. Moreover, in cases of gastric ulcer, occult blood in the feces is a most important objective symptom, for it not only clinches the diagnosis, but also indicates whether or not the ulcer is healing. During the treatment, a negative test for occult blood implies that the therapy is effective. The finding of occult blood is also the earliest and surest objective symptom in cases of carcinoma of the digestive tract. Bleeding from a carcinoma can be differentiated from bleeding from an ordinary ulcer by the fact that, in ulcer, the bleeding may
A modification of the orthotolidine test for faecal occult blood is described. It may be used when the patient is on a normal diet, provided foods containing particularly large amounts of blood—for example, liver —are excluded. The test is much less sensitive than the standard orthotolidine test. Strongly positive results are significant, but false-positive and weakly positive results may be expected in up to about 10% of cases. The occultest tablet test is suggested as a suitable alternative, particularly for ward use. © 1958, British Medical Journal Publishing Group. All rights reserved.
• 1. Standard aspirin given by mouth in customary doses had no effect on the secretion of hydrochloric acid by the stomach; soluble aspirin acted as a weak stimulus, whereas sodium salicylate solution appeared to inhibit secretion.
• 2. Acid and pepsin secretions were unchanged by the intravenous administration of sodium salicylate solution.
• 3. Blood was present in specimens of gastric juice much more frequently after standard or soluble aspirin tablets were ingested than after the oral or intravenous administration of sodium salicylate solution. Bleeding was unrelated to acid production.
• 4. No relationship between massive gastrointestinal bleeding after aspirin consumption, subjective intolerance of salicylate compounds, and hydrochloric acid secretion in response to the administration of salicylates was established.
• 5. Occult gastrointestinal bleeding during the consumption of aspirin tablets was unrelated to the capacity of the stomach to secrete hydrochloric acid and pepsin.
• 6. Both standard and soluble or buffered aspirin tablets are relatively insoluble in gastric juice; encapsulation by mucus is an important factor in retarding their dissolution.
• 7. Factors involved in mucosal damage and resistance seem more important than hydrochloric acid secretion in relation to gastrointestinal bleeding after the consumption of aspirin.
A new technique is described for the measurement of blood loss in the faeces of patients labelled with radioactive chromium (⁵¹Cr). The method is simple and is probably more accurate at low levels of faecal radioactivity than those previously described. The method will measure as little as 0·02μC of ⁵¹Cr in whole blood in a 24-hour stool.
The apparent average daily blood loss in a series of 10 normal people averaged 0·6 ml., with a range of 0·3 to 1·3 ml.
Estimations of plasma and salivary radioactivity have been made in an attempt to assess the importance of contamination from eluted ⁵¹Cr. Minor radioactivity in plasma but none in saliva was recorded. Stool contamination from such sources is thought to be insignificant.
No significant correlation existed between chemical occult blood tests and isotope measurements, where there was less than 10 ml. of whole blood in a 24-hour stool.
Ferrous fumarate (Fersamal) and ferrous carbonate (Ferrodic) may produce false-positive results with the orthotolidine tablet tests (Occultest and Hematest) if administered to patients being investigated for alimentary bleeding. Misleading results are also likely if the benzidine test is employed as a filter-paper procedure. Ferrous sulphate, gluconate, succinate, iron and ammonium citrate, and other preparations of iron have no influence on the modern tablet tests for occult alimentary bleeding.
In these days of cancer consciousness members of the medical profession are especially alert to the need for early diagnosis in all forms of malignant growth. It occurred to us that one of the standard tests for occult blood in the feces might be utilized as a screening test for gastrointestinal cancer, since this type of malignant lesion is so often accompanied with occult blood in the feces. The present study was designed to determine whether such a test could usefully be employed as a routine in office or hospital to aid in directing attention to the gastrointestinal tract in patients who might not have outstanding digestive symptoms.Although various tests for occult blood in the feces have been employed by the members of the medical profession for many years, literature concerning actual clinical utility of the tests is sparse. It would appear that they are chiefly used as a
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