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PubMedDate not supplied

Lower specificity of occult-blood test on stool collected by digital rectal examination.

BACKGROUND/AIMS: To compare the diagnostic accuracy of an immunochemical fecal occult-blood test for colorectal cancer between the stool specimens obtained during the routine screening and those during the digital rectal examination. METHODOLOGY: One hundred and fourteen patients with colorectal cancer and 228 healthy controls served as subjects of the study. Fecal occult-blood was tested by both of two methods; by the routine screening and by the digital rectal examination, and the sensitivity and specificity of an immunochemical fecal occult-blood test were determined in these two methods. RESULTS: The sensitivity and specificity were 79.8% and 96.5% in the routine screening method, and 86.0% and 79.8% in the digital rectal examination method, respectively, showing a significant difference in the specificity (P < 0.01) between these two stool collection methods. There was no significant difference in the sensitivity between these two stool collection methods. CONCLUSIONS: These findings indicate that the stool specimens collected at the time of the digital rectal examination is not suitable for testing of fecal occult-blood.

Colorectal Neoplasms↗
PubMed1998

Review article: faecal occult blood testing for colorectal cancer.

Major health organizations recommend colorectal cancer screening using faecal occult blood tests, sigmoidoscopy or both for patients 50 years of age or older who are at average risk for colorectal cancer. However, no specific recommendations have been made regarding choice of test from among the tests currently or soon to be available. Therefore, to aid clinicians in rationally choosing a particular test for faecal occult blood, published data are reviewed regarding the performance characteristics, strengths and weaknesses of the various faecal occult blood tests. New studies suggest that immunochemical tests (e.g. HemeSelect) or a combination of sensitive guaiac tests and immunochemical tests (e.g. Hemoccult Sensa and HemeSelect) are the most sensitive, specific tests for detecting colorectal carcinoma and colorectal polyps > or =1 cm.

Colonic Polyps↗
PubMed2000

Survey of internal medicine residents' use of the fecal occult blood test and their understanding of colorectal cancer screening and surveillance.

OBJECTIVE: Primary care physicians have imperfect understanding of current colorectal cancer screening guidelines and recommendations. Furthermore, compliance with colorectal cancer screening by internal medicine residents has been demonstrated to be poor. We sought to identify whether current trainees in internal medicine had adequate understanding of colorectal cancer screening and surveillance and test utilization. METHODS: We applied a structured questionnaire about colorectal cancer screening and the use of fecal occult blood tests to 168 internal medicine residents at four accredited programs in the U.S. They were also asked for recommendations about six hypothetical patients who may have been candidates for screening or surveillance. RESULTS: Seventy-one percent identified 50 yr as the currently recommended age to commence screening in an average-risk individual; 64.3% would begin screening with fecal occult blood testing and flexible sigmoidoscopy and 4.8% with colonoscopy. Most perform fecal occult blood testing on stool obtained at digital rectal exam and without prior dietary restrictions. Many use fecal occult blood testing for indications other than colorectal cancer screening. Only 29% recommended colonoscopy to evaluate a positive fecal occult blood test. Most residents plan to be screened for colorectal neoplasia at the appropriate age; significantly more opted for colonoscopy than recommended it for their patients. CONCLUSIONS: Internal medicine residents have many misperceptions regarding colorectal cancer screening and the utility of the fecal occult blood test. Educational efforts should be directed at internal medicine residents, many of whom plan careers in primary care, where most colorectal cancer screening is currently performed.

Adult↗
PubMed2005

Schistosoma japonicum and occult blood loss in endemic villages in Leyte, the Philippines.

Schistosoma japonicum has been related to anemia, but the mechanisms mediating this relationship remain unresolved. The primary objective of this study was to assess the role of occult blood loss in mediating S. japonicum-associated anemia after adjusting for age, sex, socioeconomic status (SES), and other helminth infections. The secondary objective was to identify intensity categories of risk for occult blood loss for Trichuris and hookworm after adjustment for the presence of other helminth infections. The role of occult blood loss in mediating S. japonicum-associated anemia was studied cross-sectionally in 729 individuals 8-30 years old in Leyte, The Philippines. Three stool specimens were examined in duplicate for helminth eggs. Hemoglobin, fecal occult blood loss, and anemia were measured and related to the presence and intensity of helminths. Multivariate models were made to adjust for confounding by other helminths and SES. In multivariate models, hemoglobin significantly decreased with increasing infection intensity of S. japonicum, hookworm, and T. trichuria (P < 0.0031, P < 0.0001, and P < 0.0001, respectively). Individuals with higher intensities S. japonicum and T. trichuria were significantly more likely to be fecal occult positive (odds ratio [OR] = 3.54; P = 0.008 and OR = 2.68; P = 0.013, respectively), although this was not true for individuals with hookworm. Additionally, individuals with higher intensities of S. japonicum, hookworm, and T. trichuria were all more likely to be anemic (OR = 3.7, P = 0.0002; OR = 5.3, P = 0.0003; and OR = 1.6, P = 0.021, respectively). It is likely that occult blood loss plays a role only at heavier intensity S. japonicum infections and some other mechanism, such as anemia of inflammation, may be contributing to anemia.

Adolescent↗
PubMed2001

Effect of dietary factors on the detection of fecal occult blood in cats.

Eight different diets were each fed to 6 cats to evaluate the effect on a guaiac and an o-tolidine fecal occult blood test. Fecal samples were collected from day 5 through day 7. Canine blood or pure cottage cheese were used as positive and negative controls, respectively. One hundred thirty-four fecal samples were analyzed. The dry fish (capelin) and vegetable (tapioca) diet and the pure cottage cheese diet had only negative results in both tests, whereas a canned chicken and cereal (rice) diet had negative results in all fecal samples in the o-tolidine tablet test and in 10 of 16 fecal samples in the guaiac paper test. All other fecal samples from cats eating 6 other diets and the canine blood additive were positive in both fecal occult blood tests. These results indicate that occult blood tests based on o-tolidine and guaiac are clinically useful, but cats need to be on a strict diet before the tests are used.

Animals↗
PubMed1985

The coloscreen self-test for detection of fecal occult blood.

A new method for the detection of fecal occult blood was tested in a clinical setting. The test is performed by placing a chemically treated paper pad in the toilet bowl after a bowel movement and observing for color change on the pad. This method eliminates the mechanical task of handling or gathering stool by the patient. Forty-four valid trials were completed in 19 patients with known risk factors for gastrointestinal disease. A widely used reference standard (Hemoccult II) was utilized as a control method against which the study method was compared. Concordance of the results of the study method was noted in 95.8 percent of positive cases and 100 percent of negative cases. This preliminary study supports further investigation. If the aesthetic aspects of fecal occult blood testing can be improved, there may be improvements in patient compliance with screening protocols for the early detection of colorectal cancer.

Adult↗
PubMed1989

[A new latex agglutination test for the immunologic detection of occult blood in stool].

An new latex agglutination system was developed for the detection of occult blood in the feces. Antibodies against human hemoglobin were raised in a goat. Blood in concentrations of 0.1 ml-8.0 ml/100 g feces were detected in vitro. The antibodies were separated and adsorbed to latex particles (0.3 microns). After in vitro standardisation of the new test system we compared the efficacy of the commonly used guaiac slide test for detection of occult blood in the stool (hemoccult-test) with the latex test system. A significant higher sensitivity could be reached with the latex test system. In a clinical study 61 patients were tested. In 31 of them occult blood was found with the latex test system while with the guaiac slide-test system no blood was detected using the same stool specimen. 13 of the 31 patients had a neoplastic lesion of the colon - 4 a colon carcinoma and 9 had adenomatous polyps of the large bowel larger than 5 mm in diameter. In the remaining patients the sources of intestinal bleeding were: upper gastro-intestinal bleeding sources in 8 patients and other colonic bleeding sources like diverticular disease, inflammatory bowel disease, hemorrhoids and a rectal ulcer in 8 patients. In 2 of the 61 patients the latex test was positive without endoscopic significance for the bleeding source.

Aged↗
PubMedDate not supplied

Colorectal adenomatous polyps detected by immunochemical occult blood screening.

BACKGROUND/AIMS: This study aimed to evaluate the validity of immuno-chemical occult blood screening for colorectal adenomas and to clarify the characteristics of this disease which are detected. METHODOLOGY: We studied 140 colorectal adenomas and 140 healthy controls in a hospital based case control study, in which three-day testing was conducted to assess the accuracy of the immuno-chemical occult blood screening test (total 280 patients). A further 80 colorectal adenomas 1 cm or larger, which were detected by a screening program, were compared with matched cases detected by the outpatient clinics (total 160 patients). A comparison of characteristics including tumor location, shape and histology was made between the two groups. RESULTS: Sensitivity and specificity were calculated to be 46% (61% for tumors larger than 1 cm, 30% for those less than 1 cm), and 96% respectively, showing a significant difference in sensitivity between large and small adenomas (p < 0.01). The proportion of rectal adenomas was significantly higher in the outpatient clinics (41%) than in the screening program (21%) (p < 0.05), whereas no differences were noted in the other measures. CONCLUSIONS: These results suggest that immuno-chemical occult blood is inadequate as a screening test for detecting small adenomas, as t can not differentiate between the detection of rectal adenomas from large adenomatous polyps.

Adult↗
PubMedDate not supplied

From guaiac to immune fecal occult blood tests: the emergence of technology in colorectal cancer screening.

Colorectal cancer is the second leading cause of cancer deaths in the United States for both men and women. Colorectal cancer screening is an important means for reducing morbidity and mortality. The American Cancer Society recommends five different screening regimens for adults of average risk, age 50 years and older. The optimal effectiveness of a screening program is dependent on the accuracy of the screening test used. An accurate screening test would have high sensitivity (positive) when an adenomatous polyp or cancer is present and high specificity (negative) in their absence. In April 2002, the American Cancer Society Colorectal Cancer Advisory Group concluded that the immunochemical fecal occult blood test has some advantages that merit revision of their guideline statement for fecal occult blood testing, to include the immunochemical fecal occult blood test. The advantages cited were the possibility of improved sensitivity and specificity and the lack of required dietary restrictions, which make it a more patient-friendly test. Several types of immunochemical fecal occult blood tests are discussed in this article, including their advantages and disadvantages compared with those of the traditional guaiac fecal occult blood testing.

Age Factors↗
PubMed1983

Ultrasensitive latex-agglutination-test for the specific immunochemical detection and quantification of faecal occult blood loss.

Latex agglutination was used for the development of a simple and fast immunochemical faecal occult blood test which is ultrasensitive and specific for human haemoglobin. "In vitro" detection limits of 0.0002 and 0.003 ml blood/100 g stool homogenate were obtained for the tube and filter versions of the latex-agglutination test. The quantification of the blood content in stool homogenates is possible by diluting the haemoglobin containing faecal extract until no more agglutination occurs. Considering the nonuniform distribution of blood in faeces "in vivo" sensitivities of greater than 0.002 and greater than 0.03 ml blood loss/day respectively can be expected for the tube and filter versions of the latex agglutination test. This test is about 10,000 times more sensitive than the unspecific chemical guaiac type occult blood tests and at least 1,000 times more sensitive than other immunochemical occult blood tests which use immunofluorescence, radial immunodiffusion or an enzyme immunoassay. Nuclear medical reference methods like 51Cr faecal excretion or 59Fe whole body retention cannot be used for the calibration of the ultrasensitive latex agglutination test since they are not specific for blood losses below 3 (51Cr) and 5 (59Fe) ml/day.

Colonic Neoplasms↗
PubMed2006

Can quantification of faecal occult blood predetermine the need for colonoscopy in patients at risk for non-syndromic familial colorectal cancer?

BACKGROUND: Patients at risk for non-syndromic (Lynch or polyposis) familial colorectal neoplasia undergo colonoscopic surveillance at intervals determined by clinically ascertained protocols. The quantitative immunochemical faecal occult blood test for human haemoglobin is specific and sensitive for significant colorectal neoplasia (cancer or advanced adenomatous polyp). AIM: To determine immunochemical faecal occult blood test efficacy for identifying significant neoplasia in at-risk patients undergoing elective colonoscopy. METHODS: We retrospectively identified consecutive at-risk patients who provided three immunochemical faecal occult blood tests before colonoscopy. Quantitative haemoglobin analysis was performed by the OC-MICRO automated instrument using the 100 ng Hb/mL threshold to determine positivity. RESULTS: In 252 at-risk patients undergoing colonoscopy; five had cancer, 14 an advanced adenoma and 46 a non-advanced adenoma. The immunochemical faecal occult blood test was positive in 31 patients (12.3%). Sensitivity, specificity, positive and negative predictive values for cancer were: 100%, 90%, 16% and 100%, and for all significant neoplasia: 74%, 93%, 45% and 98%. With 88% fewer colonoscopies, all colorectal cancers and 74% of all significant neoplasia would have been identified by this one-time immunochemical faecal occult blood test screening. CONCLUSIONS: A sensitive, non-invasive, interval screening test might be useful to predetermine the need for colonoscopy in this at-risk population and minimize unnecessary examinations. This favourable retrospective evaluation will be extended to a prospective study.

Aged↗
PubMedDate not supplied

Guidelines for patients undergoing faecal occult blood testing.

The literature on faecal occult blood (FOB) testing reveals a vast amount of research determining the efficacy of this test for the early detection of colorectal cancer. However, it offers no details of the information that patients require before undertaking it. The test detects the presence of blood in a patient's faeces that may not be visible on examination.

Clinical Competence↗
PubMed1999

Is upper gastrointestinal endoscopy indicated in asymptomatic patients with a positive fecal occult blood test and negative colonoscopy?

PURPOSE: There are no recommendations as to whether endoscopic evaluation of the upper gastrointestinal tract is indicated in asymptomatic patients who have a positive fecal occult blood test and a negative colonoscopy. SUBJECTS AND METHODS: All asymptomatic patients with a positive fecal occult blood test who were referred for diagnostic endoscopy were identified. Patient charts, endoscopy records, and pathology reports were reviewed. RESULTS: During the 5-year study period, 498 asymptomatic patients with a positive fecal occult blood test and negative colonoscopy were evaluated. An upper gastrointestinal source of occult bleeding was detected in 67 patients (13%), with peptic ulcer disease being the most common lesion identified (8%). Four patients were diagnosed with gastric cancer and 1 had esophageal carcinoma. In addition, 74 patients (15%) had lesions that were not considered a source of occult bleeding; these findings prompted a change in management in 56 patients (11%). Anemia was the only variable significantly associated with having a clinically important lesion identified (multivariate odds ratio = 5.0; 95% confidence interval 2.9 to 8.5; P <0.001). CONCLUSIONS: Upper gastrointestinal endoscopy yields important findings in asymptomatic patients with a positive fecal occult blood test and negative colonoscopy. Our data suggest that endoscopic evaluation of the upper gastrointestinal tract should be considered, especially in patients with anemia.

Aged↗
PubMed2000

Immunochemical fecal occult blood test is inadequate for screening test of stomach cancer.

The present study was carried out to investigate the diagnostic accuracy of the immunochemical fecal occult blood test in the screening for stomach cancer. In the hospital-based case-control study, the test was positive in 6 (14.3%) subjects with stomach cancer, in 32 (76.2%) subjects with colorectal cancer, and in 10 (7.9%) healthy subjects, respectively, showing a significant difference in detection rate between the subjects with stomach cancer and colorectal cancer (p < 0.01). In the population-based cross-sectional study, detection rate for stomach cancer was 0.13% and 0.15% for negative and positive groups decided by immunochemical fecal occult blood test, indicating no significant difference. These results reveal that the immunochemical fecal occult blood test is inadequate as the screening test for stomach cancer and suggest that examination of the upper digestive tract is unnecessary in cases where the result of fecal occult blood test is positive with no sign of colorectal diseases.

Case-Control Studies↗
PubMed1990

Evaluation of the occult blood test in screening for colorectal neoplasms. A prospective study using flexible endoscopy.

Survival rates from colorectal cancer will rise only when polyps and cancers are found at an earlier, curable stage. Consequently, the purpose of the present study was to compare the yield of colonic neoplasms from flexible sigmoidoscopy and colonoscopy with that from occult blood testing. Results from 474 flexible sigmoidoscopies and 1,115 colonoscopies were prospectively recorded during a four-year study period. Colorectal polyps were found in 111 (23.4%) patients undergoing flexible sigmoidoscopy and 325 (29.1%) patients undergoing colonoscopy. Among the 436 patients with polyps, the occult blood test was negative in 282 (64.7%). Among the 51 patients with colorectal cancers, the occult blood test was negative in 20 (39.1%). Thus, testing for occult blood missed the majority of polyps and a large percentage of the carcinomas. These data indicate that lower gastrointestinal endoscopy is superior to occult blood testing as a screening test for detecting colorectal polyps or cancers. Furthermore, given the high incidence of neoplasia in this patient population, the authors suggest that colonoscopy become the screening test of choice for colorectal cancer.

Colonic Polyps↗
PubMedDate not supplied

Sensitivity of immunochemical fecal occult blood test for colorectal flat adenomas.

BACKGROUND/AIMS: To assess the sensitivity of an immunochemical fecal occult blood test for colorectal flat adenomas, and to determine the relation between the size of flat adenomas and the results of this test. METHODOLOGY: Eleven colorectal flat adenomas under 1cm, 18 flat adenomas 1cm or larger, 187 polypoid adenomas under 1cm, 42 polypoid adenomas 1cm or larger and 144 healthy controls were investigated. Each subject was tested with an immunochemical occult blood test on two consecutive days, and the accuracy of this test was evaluated. RESULTS: The sensitivity of this test was 18% for flat adenomas under 1cm, 67% for flat adenomas 1cm or more, 19% for polypoid adenomas under 1cm and 60% for polypoid adenomas 1cm or more. Specificity was 95%, showing a significant difference in the sensitivity between flat adenomas 1cm or more and those under 1cm (p<0.05) as well as a significant difference between flat adenomas 1cm or more and polypoid adenomas under 1cm (p<0.001), whereas no significant difference was seen in the sensitivity between flat adenomas 1cm or more and polypoid adenomas 1cm or more. CONCLUSIONS: These results indicate that the sensitivity of immunochemical occult test for flat adenomas was similar to the sensitivity for common polypoid adenomas. The size of adenomas is a more important morphological factor for determining the sensitivity of this fecal occult blood test.

Adenocarcinoma↗
PubMed1981

An immunofluorescent test for faecal occult blood.

An immunological test for faecal occult blood is described, which is suitable for screening purposes. Fluorescein-labelled rabbit anti-human-haemoglobin serum is mixed with an aqueous faecal suspension, and free antibody is bound to a membrane sampler coated with human haemoglobin. The fluorescence on the membrane sampler is measured in a fluorometer, and the level of haemoglobin in the suspension is estimated. Advantages over chemical tests include absence of cross-reaction with animal haemoglobins, minimal observer error, and an adjustable sensitivity.

Colonic Neoplasms↗