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At least 19 recordsLinked to original sources
PubMed2004

Evaluation of gastric pH and guaiac measurements in neonates receiving acid suppression therapy during extracorporeal membrane oxygenation.

STUDY OBJECTIVES: To assess gastric pH measurements, evaluate the frequency of guaiac-positive gastric aspirates, and characterize the appearance of gastric aspirates in neonates receiving acid suppression therapy during extracorporeal membrane oxygenation (ECMO). DESIGN: Retrospective, observational study. SETTING: Intensive care unit in a 225-bed tertiary care pediatric referral hospital. SUBJECTS: Thirteen neonates receiving ECMO. MEASUREMENTS AND MAIN RESULTS: Gastric pH measurements, guaiac test results, appearance of gastric aspirates, and ranitidine and antacid dosing were recorded. On ECMO day 1, mean+/-SD gastric pH was 4.3+/-2.8 in the five neonates whose pH was documented. Intravenous ranitidine 2.9+/-0.4 mg/kg/day was started in all neonates by ECMO day 2. Gastric pH was less than 4.0 in seven neonates; these low pH values accounted for only 10% of gastric pH measurements. The frequency of positive guaiac results in neonates with pH measurements below 4.0 was 27% compared with 41% for neonates with a gastric pH of 4.0 or greater (p=0.125). Guaiac tests were positive in 69 (42%) aspirates in 11 neonates. Of the guaiac-positive aspirates that had a corresponding pH measurement, 94% had a pH of 4.0 or greater. Guaiac-positive aspirates had evidence of bile (49%), antacid (17%), and blood (7%) in gastric fluid. In six patients, ranitidine dosages were increased to 3.9+/-0.6 mg/kg/day due to low pH and/or positive guaiac results. In two of these neonates, gastric pH remained below 4.0 in nine of 35 pH measurements despite increased ranitidine dosing. Guaiac results remained positive in all subsequent aspirates in five out of six of these neonates. No neonates developed clinically significant upper gastrointestinal bleeding (UGIB). CONCLUSIONS: Gastric pH is variable in neonates receiving histamine2-receptor antagonist and antacid therapy during ECMO, and gastric pH of 4.0 or greater does not decrease the frequency of guaiac-positive aspirates. Higher gastric pH measurements are confounded by duodenogastric reflux and the presence of blood and/or antacid in gastric fluid. Motility agents in combination with acid suppression therapy for prevention of UGIB may be necessary in this setting based on gastric pH measurements, appearance of gastric aspirates, and guaiac testing.

Antacids↗
PubMed1997

Immunological testing for occult blood in patients with acute infectious diarrhea. Can it improve the specificity of the guaiac test?

Microscopic stool examination can distinguish inflammatory from noninflammatory diarrheas. The modified guaiac test was shown to have good correlation to stool microscopy. In a prospective study we evaluated the diagnostic accuracy of a modified guaiac test (Colo-Rectal-Test, Roche) and of an immunological test for fecal haemoglobin (Colo-Immun-Test, Roche) in relation to the diarrheal pathogens identified and compared it with the stool microscopy. In 304 patients, clinical presentation, stool microscopy, stool culture, and modified guaiac test were recorded. Sensitivity of the guaiac test was 69% as compared to 63-67% for the stool microscopy. Specificity could be improved by 10-15% using an immunological test to exclude false-positive guaiac reactions. A modified guaiac test can replace microscopic stool examination to distinguish between inflammatory and non-inflammatory diarrhea. Immunological testing for occult blood can improve the specificity of the guaiac test, but is too elaborate to serve as a screening test. The modified guaiac test can easily be handled by community health workers and could be important in the diagnostic work-up for acute infectious diarrhea.

Acute Disease↗
PubMed2006

A quantitative immunochemical faecal occult blood test is more efficient for detecting significant colorectal neoplasia than a sensitive guaiac test.

BACKGROUND: The sensitive guaiac faecal occult blood test, Haemoccult SENSA (HOS; Beckman Coulter, Fullerton, CA, USA), is our standard screening test for significant colorectal neoplasia. We evaluated an automatically-developed, quantified human haemoglobin immunochemical faecal test, OC-MICRO (Eiken Chemical Co., Tokyo, Japan), to improve test specificity and so reduce the colonoscopy burden. AIM: To compare guaiac faecal occult blood test and immunochemical faecal test diagnostic efficacy and costs for identifying significant neoplasia. METHODS: Colonoscopies were performed on patients who prepared three daily guaiac faecal occult blood tests with or without immunochemical faecal tests. RESULTS: Total colonoscopy was performed on 151 subjects who prepared both guaiac and immunochemical faecal tests (group 1) and the positive predictive values (PPV) were also compared to those of 162 subjects undergoing colonoscopy for positive guaiac faecal occult blood tests (group 2). In group 1, comparative sensitivity, specificity, and PPVs for significant neoplasia with guaiac faecal occult blood test were 75%, 34%, and 12% (PPV, 18% for group 2) and with immunochemical faecal test were 75%, 94% and 60% (P < 0.01 for specificity). The number of colonoscopy examinations needed to detect a significant neoplasm because of positive faecal occult blood tests was six to eight with HOS and two with OC-MICRO at 21-31% the cost of evaluating a positive guaiac faecal occult blood test. CONCLUSION: An immunochemical faecal test maintains the high sensitivity of guaiac faecal occult blood test, but significantly reduces the colonoscopy burden and screening costs.

Aged↗
PubMed2005

The immunochemical faecal occult blood test leads to higher compliance than the guaiac for colorectal cancer screening programmes: a cluster randomized controlled trial.

INTRODUCTION: We conducted a cluster-randomized trial aimed at assessing the effect of the type of faecal occult blood, guaiac or immunochemical test on screening compliance. METHODS: We sampled 130 general practitioners (GPs) who consented to participate in the trial. We randomly allocated half of them to the guaiac (Hemo-Fec) and half to the immunochemical test (OC-Hemodia). We sampled 2/10 of the GPs' 50-75-year-old patients (n=7332) and randomly divided this population into half. One half was invited to be screened at the GP's office and the other to the nearest gastroenterology ward. The principal outcome was the percentage of returned tests. RESULTS: The immunochemical test had a compliance of 35.8% and the guaiac of 30.4% (relative risk [RR] 1.20; 95% confidence interval [CI] 1.02-1.44). The difference was mostly due to a higher probability of returning the sample: 93.8% and 88.6% for immunochemical and guaiac, respectively (RR 1.06; 95% CI 1.02-1.10). The guaiac test had a higher prevalence of positives (10.3% versus 6.3%, RR 0.603; 95% CI 0.433-0.837). There was a higher variability in the results obtained with the guaiac test compared with the immunochemical (F[1, 12] = 16.25; P=0.0017). CONCLUSIONS: Compliance is more likely with the immunochemical than the guaiac test, independent of the provider. Guaiac tests show a higher variability of the results among centres. The successful implementation of a screening programme requires a period of standardization of the test reading in order to avoid unexpected work overload for colonoscopy services.

Aged↗
PubMed1989

Effect of iron on the guaiac reaction.

Most studies show that oral ingestion of iron does not cause a positive stool guaiac reaction. However, all in vitro studies show that iron does cause a positive guaiac reaction and some in vivo studies have shown a positive stool guaiac reaction in response to oral iron. This study examines this unresolved question. Twenty-five normal volunteers were given 900 mg of ferrous sulfate a day. Two Hemoccult II and two HemoQuant tests were obtained before and during iron therapy. All Hemoccult II tests were negative before and after oral iron. Four HemoQuant tests were slightly elevated before oral iron and one was slightly elevated after oral iron. Ferrous sulfate, 300 mg, was dissolved in 1 L of water. The solution was acidic (pH = 3.9) and produced a positive Hemoccult II test. When the solution was titrated with sodium hydroxide to a pH of greater than or equal to 6.0, iron precipitated out and the mixture no longer produced a positive Hemoccult II reaction. Our data show that ferric iron (Fe3+) in solution will give a positive guaiac reaction directly and ferrous iron (Fe2+) will give a positive guaiac reaction after hydrogen peroxide is added because it oxidizes Fe2+ to Fe3+. Iron solutions are acidic and when titrated toward a neutral pH, the iron is precipitated out and the solution is then guaiac-negative. Thus, our in vivo data confirm most previous in vivo studies; furthermore, the discrepancy between in vivo and in vitro studies can be explained as a pH-dependent phenomenon of in vitro iron solutions. Oral iron should not cause a positive guaiac reaction, and the HemoQuant results show no increase in occult blood loss in subjects on oral iron therapy.

Administration, Oral↗
PubMed2006

Immunochemical testing of individuals positive for guaiac faecal occult blood test in a screening programme for colorectal cancer: an observational study.

BACKGROUND: Screening for colorectal cancer by use of guaiac-based faecal occult blood tests (FOBT) reduces disease-specific mortality. However, due to imperfect specificity, about half of individuals positive for guaiac FOBT are negative for neoplasia on colonoscopy. We aimed to assess whether the testing of individuals positive for guaiac FOBT in a screening programme for colorectal cancer by use of a sensitive immunochemical FOBT could select more appropriately those who should receive colonoscopy. METHODS: We invited individuals who were guaiac FOBT positive in the second screening round of a pilot study in Scotland, UK, to give two samples, each from separate stools, for immunochemical FOBT while awaiting colonoscopy. Results were classed as: both samples negative (N/N), one sample negative and one positive (N/P), and both samples positive (P/P); data were assessed for sampling bias. We compared immunochemical findings with those from colonoscopy using odds ratios of positive samples (P/P) versus negative (N/N and N/P). Sensitivity, specificity, and positive and negative likelihood ratios for cancer, and for cancer and high-risk adenomatous polyps were also calculated. FINDINGS: 1486 participants were invited and 801 (54%) sets of duplicate samples were returned. We found no evidence of sampling bias with regard to sex, age, or degree of positivity on guaiac FOBT. Of 800 sets returned with consent and analysed, 173 (22%) were N/N, 129 (16%) were N/P, and 498 (62%) were P/P. Chi2 test showed a highly significant positive correlation between degree of positivity on guaiac FOBT and on immunochemical FOBT (p<0.003). 795 individuals had data for colonoscopy: one (<1%) of 171 N/N participants and one (<1%) of 127 N/P participants had colorectal cancer, compared with 38 (8%) of 497 P/P participants; adenomatous polyps were found in 28 (16%) N/N individuals, 24 (19%) N/P individuals, and 193 (39%) P/P individuals. Normal colonoscopy was less common in the P/P group (85 [17%]) than in the N/N (67 [39%]) and N/P (49 [39%]) groups. The odds ratio for P/P being associated with cancer was 7.57 (95% CI 1.84-31.4) and with high-risk adenomatous polyps was 3.11 (1.86-5.18). Sensitivity of a P/P result for cancer was 95.0% (81.8-99.1), and for cancer and high-risk adenomatous polyps was 90.1% (84.4-94.0); specificity was 39.5% (36.0-43.1) and 47.8% (43.9-51.8), respectively. INTERPRETATION: Immunochemical FOBT for individuals with positive guaiac FOBT could decrease substantially the number of false positives in a screening programme for colorectal cancer.

Aged↗
PubMed1992

Admission stool guaiac test: use and impact on patient management.

PURPOSE: A stool guaiac test is often performed on newly hospitalized patients as part of the admission evaluation. However, little is known regarding the value of testing stool obtained by digital rectal examination. We sought to document the use of the admission stool guaiac test in a teaching hospital, to determine its diagnostic yield, and to assess its potential benefit to patients. MATERIALS AND METHODS: We performed a retrospective review of the medical records for 264 consecutive patients admitted to internal medicine services during a single month, of whom 202 received a stool guaiac test on admission. Information was collected on the frequency of guaiac testing, indications for testing, test results, and diagnoses established. RESULTS: Criteria were established to distinguish "clinically indicated" from "routine" use of the admission stool guaiac test. Indicated tests were positive more often than routinely performed tests (35% versus 11%, p less than 0.001). Most patients with positive tests received further testing for gastrointestinal disease, whether or not the test was indicated. Of 104 patients with indications, 25 were ultimately found to have gastrointestinal lesions, most of which were clinically important. Of 98 patients tested routinely, only four had diagnoses established, of whom three had benign conditions. Four of five patients with cancer had clinical indications for testing. The fifth was diagnosed only after he experienced gross rectal bleeding several days after admission. CONCLUSIONS: Like other commonly applied diagnostic tests, the stool guaiac test obtained during the admission physical examination is best reserved for patients whose clinical presentation provides a reason for testing. In patients without clinical indications, the test is of uncertain value and only infrequently leads to important diagnoses.

Academic Medical Centers↗
PubMed1997

Incidence of stool guaiac conversion following extracorporeal shock wave lithotripsy.

OBJECTIVES: To study, in a prospective fashion, acute traumatic effects on the gastrointestinal tract of patients treated by extracorporeal shock wave lithotripsy (ESWL). METHODS: Stool samples from each of 54 patients were tested before and after ESWL for conversion to hemoccult positive. A minimum of one negative pre-ESWL stool guaiac test was required for inclusion into the study. A minimum of two stool guaiac tests were done after ESWL to verify negativity. Patients who converted to a positive hemoccult test after ESWL were then evaluated by colonoscopy for the source of bleeding. RESULTS: Fifty patients completed the study. A single patient (2.0%) converted to a positive post-ESWL hemoccult test and was evaluated with colonoscopy. This patient was found to have two benign adenomatous polyps in the sigmoid and descending colon after treatment for a left renal pelvis calculus. An additional patient with a slightly positive post-ESWL conversion refused further evaluation. The overall post-ESWL conversion rate to guaiac positive, therefore, was less than 4% (2 of 51 patients). CONCLUSIONS: There is no evidence of significant trauma or detectable bleeding in the normal gastrointestinal tract caused by ESWL as measured by postprocedure stool guaiac testing. Guaiac testing of the stool after ESWL may unmask pre-existing gastrointestinal disease. Therefore a positive guaiac test after ESWL warrants further evaluation. This study reaffirms that ESWL is a safe, minimally invasive technique for the treatment of urolithiasis, without significant adverse side effects on the gastrointestinal tract.

Digestive System↗
PubMed2003

Fecal occult blood testing in a general medical clinic: comparison between guaiac-based and immunochemical-based tests.

PURPOSE: Guaiac-based fecal occult blood tests are limited by poor patient compliance, and low sensitivity, specificity, and positive predictive value. Newer immunochemical-based tests are designed to improve accuracy and patient compliance. We compared patient compliance and the test characteristics of these two types of tests. METHODS: The laboratory outcomes associated with use of different fecal occult blood tests were examined in a Veterans Affairs-based general medicine clinic that was divided into two firms with similar patient and provider characteristics. Tests were ordered for colorectal cancer screening or for symptom evaluation. Patients were given one of the two tests depending on their firm. The completion and positivity rates, time to test completion, completion of diagnostic follow-up, and positive predictive values were compared. RESULTS: The percentage of returned test cards was similar between the two groups (47% [1369/2964] for guaiac-based tests vs. 48% [1410/2965] for immunochemical-based tests) as was the positivity rate (9.0% [122/1396] and [128/1410] for both groups). In patients with positive tests who underwent further colon evaluation, the proportion with adenomas was similar between groups (59% [38/64] vs. 58% [40/69]). However, 17% (12/69) with a positive immunochemical-based test had an adenoma >1 cm or a colorectal malignancy, versus 30% (19/64) for guaiac-based tests (P = 0.09). CONCLUSION: Overall, immunochemical-based and guaiac-based fecal occult blood tests had comparable performance. However, although immunochemical-based testing is reported to be easier for patients than guaiac-based testing, we found that patients were no more likely to return cards for analysis. The similar positive predictive value and additional cost of immunochemical-based tests call into question their utility in general practice.

Aged↗
PubMed1997

Performance characteristics and comparison of two immunochemical and two guaiac fecal occult blood screening tests for colorectal neoplasia.

A new immunochemical test for stool Hb, FlexSure OBT, was compared with the immunochemical HemeSelect and guaiac Hemoccult II and Hemoccult SENSA tests. Blinded development of test cards smeared with stools having added human blood showed better analytical sensitivity of FlexSure OBT (0.2 ml blood/100 g feces), than Hemoccult SENSA (> or =0.5 ml) or Hemoccult II (> or =1.0 ml). All four stool tests were prepared by 403 subjects having endoscopic examinations. The guaiac tests and FlexSure OBT were easy to prepare and develop. The positivity rate of Hemoccult SENSA was 8.7%, Hemoccult II 6%, FlexSure OBT 4.2%, and HemeSelect 3.4%. In this mainly asymptomatic (97%) population, 98% were free of clinically significant neoplasia (five had cancers, three had adenomas > or =1.0 cm). Sensitivity for cancers or adenomas > or =1.0 cm was similar for all tests (62.5-86%, NS) and Hemoccult SENSA had the lowest specificity (92% vs 95-98%, P < 0.05); but both Hemoccult II and Hemoccult SENSA had significantly lower predictive positive values (21% and 14%) than either FlexSure OBT (29%) or HemeSelect (50%) (P < 0.05). If both Hemoccult SENSA and FlexSure OBT were positive in the same subjects (1.7%), sensitivity for cancer or adenomas > or =1.0 cm (50%) was not significantly better than guaiac tests, but specificity (99.2%) and predictive positive (57%) values were improved (P < 0.05). In this population, guaiac tests were as sensitive as immunochemical tests for clinically significant colorectal neoplasia, but with significantly lower predictive positive values. A combination of a sensitive guaiac test (Hemoccult SENSA) and a specific confirmatory test for human Hb (FlexSure OBT) provided high specificity, comparable to HemeSelect.

Adenoma↗
PubMed2003

A sensitive guaiac faecal occult blood test is less useful than an immunochemical test for colorectal cancer screening in a Chinese population.

BACKGROUND: Colorectal cancer screening by guaiac faecal occult blood test has been shown to reduce the incidence and mortality of colorectal cancer in Western populations. The optimal faecal occult blood test, whether guaiac or immunochemical, for colorectal cancer screening in the Chinese population remains to be defined. AIM: To compare the performance characteristics of a sensitive guaiac-based faecal occult blood test (Hemoccult SENSA) and an immunochemical faecal occult blood test (FlexSure OBT) in a Chinese population referred for colonoscopy. METHODS: One hundred and thirty-five consecutive patients who were referred for colonoscopy and who met the study inclusion criteria took samples for the two faecal occult blood tests simultaneously from three successive stool specimens, with no dietary restrictions. All tests were developed and interpreted by a single experienced technician who was blind to the clinical diagnosis. The sensitivity, specificity and positive predictive value for the detection of colorectal adenomas and cancers were estimated for the two tests. RESULTS: The sensitivity, specificity and positive predictive value for the detection of significant colorectal neoplasia (adenomas > or = 1.0 cm and cancers) were 91%, 70% and 18% for Hemoccult SENSA and 82%, 94% and 47% for FlexSure OBT. The specificity and positive predictive value were significantly higher for FlexSure OBT than for Hemoccult SENSA (P < 0.001 and P = 0.016, respectively). Combining the positive results from both faecal occult blood tests did not improve the accuracy. CONCLUSION: The positive predictive value of the immunochemical faecal occult blood test for the detection of significant colorectal neoplasia was 29% better than that of the sensitive guaiac-based test. This may relate to the Chinese diet and requires further study. The poor specificity of the sensitive guaiac-based test, without dietary restriction, makes it less useful for colorectal cancer screening in a Chinese population.

Adult↗
PubMed1989

Substances that interfere with guaiac card tests: implications for gastric aspirate testing.

Previous studies have shown that acidic pH and several ingestible substances can cause misleading guaiac tests of gastric aspirates. In this in vitro study, over 100 foods, beverages, and drugs were diluted to concentrations potentially present in the stomachs of outpatients being evaluated for gastrointestinal bleeding. These were mixed with known concentrations of blood and tested with different brands of guaiac cards. Decreased guaiac test sensitivity was associated with activated charcoal, dimethylaminoethanol, red chile, N-acetylcysteine, rifampin, red Jell-O (General Foods Corp, White Plains, NY), orange juice, Pepto-Bismol (Norwich Eaton Pharmaceuticals, Norwich, NY), simethicone, spaghetti sauce, and several red wines. Chlorophyll and methylene blue-containing tablets produced false-positive results, but other blue and blue-green colored tablets did not, except at high concentrations. Previously described false-negative results with vitamin C, bile, and certain antacids were confirmed, as were false-positive results with iodide, bromide, cupric sulfate, iron salts, and hypochlorite. Physicians should exercise caution when interpreting guaiac card tests of gastric aspirates, especially in the outpatient setting.

False Positive Reactions↗
PubMed1992

Guaiac and immunochemical tests for faecal occult blood in colorectal cancer screening.

Seven hundred and eighty-six subjects spontaneously referring to our Center performed two guaiac (Rehydrated Hemoccult II (R.HO), and Hemoccult Sensa (HO S.)), and two immunochemical (OC Hemodia (Hdia) and Hemeselect (Hsel)) faecal occult blood tests on three consecutive faecal determinations. The positivity rates of 3 day R.HO, HO S., Hdia, and Hsel were 4.8%, 5.6%, 8.4% and 11.2% respectively. One hundred and thirty-five of the 150 subjects with at least one positive test completed the diagnostic work-up. Cancer was detected in three subjects and adenomas in 15. Three-day specificity estimates of R.HO, HO S., Hdia and Hsel in the overall series were 96.1%, 96.0%, 93.8% and 91.2% respectively, the differences between guaiac and immunochemical tests being significant. Corresponding values of specificity as determined on the first faecal sample only in the overall series were 98.1%, 98.3%, 96.1% and 94.9% respectively. No significant difference in specificity is evident when 3-day guaiac tests are compared to 1-day immunochemical ones. Three-day immunochemical testing is not recommended for screening purposes due to its very low specificity. Nevertheless, 1-day immunochemical testing is almost as specific as 3-day guaiac testing. A preliminary estimate of colonic neoplasms detection rates shows no difference as well. The benefit of 1-day testing on screening acceptability is evident, but the impact on sensitivity should be evaluated in a screening situation with a proper study design and a larger sample size.

Carcinoma↗
PubMed1992

Guaiac testing in the diagnosis of rectal trauma: what is its value?

Rectal examination with guaiac testing is a standard part of the emergency department evaluation of acutely traumatized patients. Its major role is in the recognition of occult bowel injury. We questioned its efficacy in detecting occult rectal injury in patients with penetrating trauma. We reviewed the charts of 19 patients with suspected rectal injury. Ten injuries were to the abdomen, nine to the buttock, and three to the thigh. Guaiac testing was 69% (11/16) sensitive and 33% (1/3) specific. Rigid sigmoidoscopy was 100% (12/12) sensitive and 67% (2/3) specific. Sensitivity was 100% (8/8) when the two were combined. Our findings suggest that guaiac testing is not accurate enough to rule out the presence of occult rectal injury. The result of guaiac testing must not influence the decision to further evaluate patients with high-risk injuries.

Adult↗
PubMed1981

Diagnosis of occult gastrointestinal lesions by stool guaiac testing in a geriatric hospital.

In a long-term care facility, the fecal guaiac test for occult blood was used as a screening method to detect gastrointestinal (GI) bleeding lesions. The study involved 450 chronically ill hospitalized patients whose average age was 70 years. Each underwent 6 fecal guaiac tests for three consecutive days while receiving a standardized meat-free, high-fiber diet. The 21 patients in whom the fecal hemoccult test yielded positive findings were further studied with x-ray upper GI series, barium enema, and fiberoptic examination of the upper and lower GI tract when necessary. In 4.7 percent of this population, the guaiac test gave positive results, which usually involved only 1 or 2 of the 6 guaiac slides. On further study it was found that 2 patients had large-bowel tumors, 5 had duodenal ulcers, 1 had gastric cancer, and 7 had diverticulosis. The incidence of colon cancer in this population was the same as that reported in other studies, but the incidence of duodenal ulcers was high. In 20 of the 21 patients with positive test findings, a lesion of the GI tract was found. The therapeutic implications of such screening are important. This study emphasizes the value of routine fecal hemoccult testing of whole institutional populations once or twice a year.

Adult↗
PubMed1985

False-positive guaiac testing with iodine.

The guaiac-impregnated test slide (Hemoccult) used in testing for occult blood in the stool gave a false-positive reaction in a trauma patient when a povidone-iodine antiseptic solution (Betadine) was used prior to the insertion of a urinary catheter. Laboratory testing using serial dilutions of povidone-iodine solutions indicates that as little as 0.005 mL of a 1:1,000 dilution will give a positive guaiac reaction. Separate testing confirms that the iodine component is responsible for this false-positive reaction. The mechanism is probably direct oxidation of the alpha-guaiaconic acid chromogen. Patients with perianal decubiti who are being treated with povidone-iodine solution, or those who have recently had a urinary catheter inserted, may need to have the area washed prior to guaiac testing. Antiseptics not containing iodine may be used in trauma patients to prevent false-positive guaiac reactions.

Adult↗
PubMed1984

New screening method for occult gastrointestinal bleeding: immunologic and guaiac slide tests.

A valid mass screening method for occult, bleeding gastrointestinal pathology including colorectal cancer should be monospecific for human hemoglobin, sensitive for approximately 3 mg of human blood per 1 g of stool, capable of differentiating upper and lower gastrointestinal bleeding, cost effective, uncomplicated, and acceptable to patients. Hemoccult II, a guaiac peroxidase detection test, is nonspecific for human blood and cannot differentiate between upper and lower gastrointestinal bleeding. A radial immunodiffusion slide test for detecting human hemoglobin was compared with a guaiac test over a four-year period in 211 patients. in gastrointestinal problems diagnosed by endoscopy, roentgenographic rays, and other procedures, the Hemoccult II was positive in 9 of 41 cases of upper gastrointestinal tract origin (21 percent detection rate), whereas the radial immunodiffusion method, expected to be negative as a result of action of gastrointestinal proteases, was positive in only 3 and negative in 38 of the 41 samples (92 percent accuracy). The two tests were equally effective in detecting lower gastrointestinal bleeding (14 of 37 samples, 37 percent accuracy). The findings of this study indicate that the immunologic test may remedy the deficiencies of the guaiac test. The concomitant use of the immunologic and appropriately sensitive guaiac test appears to fulfill screening test requisites.

Colonic Neoplasms↗
PubMed1983

Sensitivity of guaiac-impregnated cards for the detection of colorectal neoplasia.

The sensitivity of the guaiac-impregnated card, hemoccult II, for the detection of colorectal neoplasia was tested in 213 patients undergoing elective colonoscopy over a 10-month period. Contrary to statements in standard texts as to the high sensitivity of guaiac-impregnated cards for the detection of these tumors, our results demonstrate only a 52% sensitivity for colorectal carcinoma and a 23% sensitivity for adenomatous polyps over 1.0 cm in diameter. We compare these results to other studies testing hemoccult sensitivity in the presence of colorectal neoplasia. This relatively low sensitivity rate emphasizes that the use of guaiac-impregnated cards alone does not exclude colorectal carcinoma in any patient.

Adult↗