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Diagnostics: Kits,
Instruments , Fecal blood, H. pylori test kit |
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Fecal Blood, H. pylori Test Kits
fecal blood test kit, H pylori test kit, H
pylori testing, fecal occult blood test, colon cancer screening, colon cancer test, colon
cancer detection, h pylori breath test, h pylori blood test, ulcer test
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Test
Card Description and Instructions
There are two windows on each test card to which a stool or gastric specimen can be
applied. Attached to each card there is a liquid-containing pouch which is released by
pulling the tab. After the tab is pulled, you will see a "+" control on the edge
of each test card which must turn blue indicating the test has functioned correctly. A
blue color in the window test areas is a positive result. No blue in the test areas means
no blood was detected.
1. Open the front cover of one Hemaprompt card and using the applicator spread a very thin
smear of the specimen on one of the windows. When testing feces, from a different area of
the stool, spread a second specimen thinly on the second window. Close the card cover.
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2. After closing the card cover turn to
the back of the card. Grip with the left thumb and finger at the point indicated and hold
the foil tab with the right thumb and finger. Alternatively lay the closed card face down
flat on a table and hold in place with your left thumb at the indicated grip point. Slowly
and steadily pull the foil tab all the way out to the right and off. Wait one minute after
pulling the tab before reading the test result.
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3. Check that the "+" indicator marked "control" has turned blue. If
it has not turned blue the test card is faulty and should be discarded. After one minute,
inspect the indicated window test areas. Any shade of blue no matter if it is faint or a
small speck in either one of the test areas is a positive reaction and indicates that
blood is present. Do not read after 3 minutes as the blue color may fade. After noting the
results, discard (do not flush) the card and applicator safely. See Examples of Results
page for colored illustrations of results you might expect to see.
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Intended Use
HemaPrompt fg is a guaiac-based
in-vitro slide method for the qualitative detection of occult blood in feces and gastric
aspirate or vomitus by medical professionals only. For fecal testing, it is a useful aid
in the diagnosis of a number of gastro-intestinal disorders, and is recommended for use in
1) routine physical examinations 2) routine hospital testing 3) screening for colorectal
cancer or gastro-intestinal bleeding from any other source. For the testing of gastric
contents it is used for the early detection of occult blood in conditions such as gastric
trauma, gastric or duodenal ulceration, gastric cancer, esophageal varices, situations of
likely exogenous or endogenous gastritis, leukemia, and hereditary telangiectasia. These
conditions may be encountered in the emergency room, recovery room or intensive care.
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Summary and Explanation
Summary and Explanation Principle Reagents and Materials Supplied Storage and
Stability Warning and Precautions Patient Preparation Specimen Collection Interpretation
of Results Limitations of Test Expected Results Performance Characteristics Home The
guaiac-peroxidase reaction, initially described by Van Deen [1], when adapted to the slide
format, has been a widely used method for the detection of fecal occult blood, which is a
sign of many gastro-intestinal disorders, and signals the necessity of follow-up by other
diagnostic methods. Guaiac slide tests overcome the instability of guaiac solution and the
hypersensitivity of benzidine and ortho-tolidine. The same reaction has also been used for
the detection of occult blood in gastric contents ( when suitably buffered as with
HemaPrompt fg ) indicative of a number of disorders such as gastritis, ulcer, or cancer.
Blood is normally absent in the stomach, and when present secondary to benign ulcer will
disappear with adequate therapy, but if persistent during medical treatment, malignancy is
to be suspected [19]. HemaPrompt fg provides a method of testing for the presence of
occult blood in which a thin smear of feces or gastric contents to be tested is applied to
the guaiac paper window. The convenience of HemaPrompt fg is that the buffered developing
solution is contained on each individual test card in a pre-measured quantity, and is
applied automatically to the guaiac paper by pulling the tab on the card and unaffected by
pH in the range of 1.0 - 8.0. The application of developer solution from a separate
dispenser bottle is thus avoided. In addition, a monitor printed on the guaiac paper
indicate if the chemicals are functioning correctly. HemaPrompt fg results cannot be
considered conclusive evidence of the presence or absence of GI bleeding or pathology.
False positive/negative reactions are known to be caused by a person's particular diet or
medications (see Patient Preparation below). The test is intended as a preliminary
indicator and not as a replacement for other diagnostic procedures such as gastroscopy,
sigmoidoscopy, barium enema, and x-ray studies.
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Principle
The use of guaiac as a test for the presence of blood is based on the oxidation of
phenolic compounds present in guaiac to quinones, resulting in the production of a blue
color [2]. If blood is present, the heme portion of the hemoglobin (Hgb) molecule can
function in a pseudoenzymatic manner, catalyzing the release of oxygen from hydrogen
peroxide which in turn causes the oxidation of guaiac. HemaPrompt fg is a version of the
laboratory guaiac slide test for fecal or gastric occult blood, and is composed of
guaiac-impregnated paper mounted on a cardboard frame which permits sample applications to
one side with development and interpretation from the reverse side. Feces or gastric
contents containing occult blood contacts the guaiac impregnated paper and a
pseudoperoxidase reaction occurs when developing solution is brought into contact with the
guaiac paper, by pulling the tab. The test paper will turn blue in less than 60 seconds in
the presence of more than 2mg hemoglobin/ gram of feces, and will gradually fade in 5 - 15
minutes. It will also turn blue in the presence of more than 0.01 mg hemoglobin/ ml of
gastric fluid in less than 60 seconds, (see Performance Characteristics below). Monitors
on the guaiac slide indicate if the chemicals are functioning correctly
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Reagents and Materials Supplied
Guaiac impregnated paper and developing solution are both mounted on each slide, as is a
control monitor. The developing solution of 60-70% denatured ethyl alcohol and
approximately 6% hydrogen peroxide diluted approximately 20% by a buffering mixture is
contained within a developing pad and is exposed after pulling the tab. The positive
monitor contains a hematoid equivalent to a minimum of 2.0 mg Hb per gram feces. The fecal
specimen is usually applied directly by the gloved finger, from toilet paper or by
applicator (as supplied). Gastric specimens can be applied directly from the naso-gastric
tube or by obtaining a specimen from the container of gastric juice by means of the
applicator supplied or by a clean cotton tipped swab ( not supplied). There are 50 slides
with applicators in each box (Catalogue Number HPfg). Important Note Current U.S. Postal
Regulations prohibit mailing completed test slides in standard envelopes.
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Storage and Stability
Each slide is equipped with controls to monitor the effectiveness of the chemicals and
hence the test itself. The positive control must turn blue. Failure of the control to
produce the appropriate color reaction is indicative of product deterioration and the test
results are invalid. HemaPrompt slides should be stored at room temperature(15-30C) and
should be protected from heat, sunlight, fluorescent light, U-V radiation, humidity,
volatile chemicals and gases. Do not refrigerate or freeze. They are stable until the
expiration date indicated on each slide, after which time the slide should not be used.
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Warning and Precautions
Reagents and Materials Supplied Storage and Stability Warning and Precautions Patient
Preparation Specimen Collection Interpretation of Results Limitations of Test Expected
Results Performance Characteristics Home HemaPrompt is intended for in-vitro diagnostic
use only. Skin or eye contact with the developing pad which is exposed after pulling the
tab, should be avoided; flush the affected area with water should contact occur. Ingestion
may be fatal or cause blindness. Keep away from heat, sparks or open flame.
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Patient Preparations
i) Fecal Occult Blood. In the acute situation no particular preparation will be possible,
but for screening purposes a special diet as described below is recommended to decrease
the possibility of false positive results. On the other hand, dispensing with such a diet
for initial screening purpose may increase patient compliance but a positive result under
these circumstances would indicate the need to repeat the test in which a special diet two
days prior to and during the three day test period is followed. This diet should EXCLUDE
red and rare meats, horseradish, raw fruits and vegetables like broccoli, cauliflower, red
radish, cantaloupe, parsnips and turnips, or other high peroxidase containing vegetables,
which can cause false positive results. An acceptable diet could include cooked fruit and
vegetables such as spinach and corn as well as lettuce, prunes, grapes, and apples.
Cereal, and well cooked fish and fowl are also acceptable. If any of the recommended foods
are known to cause discomfort, the patient should consult his or her physician. Because
gastro-intestinal lesions may bleed intermittently and blood in feces is not distributed
uniformly, all patients who test positive regardless of diet should be followed up with
additional diagnostic procedures. Certain medications such as aspirin,[3] indomethacin,
phenylbutazone, reserpine, corticosteroids and nonsteroidal anti-inflammatory drugs can
cause gastro-intestinal bleeding and thus give positive reactions; dosages of greater than
250mg. of Vitamin C per day have been shown to cause false negative results[4], while iron
containing compounds have been mentioned as a cause of false positive reactions[5].On the
advice of the physician, these medications might be temporarily discontinued for 7 days
prior to and during the test period. ii) Gastric Occult Blood Elective collection of
gastric juice is rarely conducted. False positive and false negative reactions can be
caused by medications and foods such as mentioned above. In addition, using a guaiac based
test with an unbuffered developer, certain histamine (H2) antagonists such as cimetidine
(Tagamet) have been shown to cause false positive reactions [16] as with iron, and false
negative reactions can result from low pH, but because of the buffering of the developer
used in HemaPrompt, interfering reactions by recommended dosage of ranitidine (300mg),
ferrous sulfate (300mg),cimetidine (300mg) or antacids (Mylanta10-20 ml) have not been
observed [21].
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Specimen Collection
Feces can be obtained by direct rectal exam, but for screening purposes stool samples
should not be collected if the patient is experiencing menstrual bleeding, constipation
bleeding, bleeding hemorrhoids when rectal suppositories or medication is being used or if
there are cuts on the hand. It is recommended that smears be collected from two different
areas of each stool from three consecutive bowel movements as closely spaced in time as
possible,[6][7], or by the physician following a rectal exam. Using toilet paper, a
specimen is taken from stool smeared on the bowl and above the toilet water level, from
the toilet paper used following defecation, or from a specimen caught in a clean cup.
Application to the slide may be performed from the gloved finger (as after a rectal exam),
applicator, or by use of the toilet paper described above. It is important that the stool
specimen is applied as a thin smear to each of the slide windows and that no more than 4
days should elapse between preparation and testing, with patients being instructed to
return all slides to the physician as soon as possible. Rehydration of the specimen is not
necessary nor recommended. Gastric Contents obtained from the naso-gastric tube or vomitus
can be applied directly from the naso-gastric tube or by means of a cotton tipped swab. In
each case only a thin smear of material should be applied to the test area on the slide
and developed (by pulling the tab as described on each slide) immediately and read within
one minute. The specimen as applied to the slide or by itself may be stored up to 24 hours
at room temperatures or up to 5 days at 30C before developing. Occasionally gastric
samples applied to the slide may appear green in which circumstances only the formation of
blue can be regarded as positive Patient specimens and all materials that come in contact
with them, should be handled as potentially infectious and disposed of with proper
precaution. Do not allow contact with skin or mucous membranes.
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Interpretation of Results
Results Limitations of Test Expected Results Performance Characteristics Home For both
Gastric and Fecal samples, after pulling the tab out to its limit, results are to be read
from the reverse side of the card and through the clear plastic window. ANY trace of blue
coloration is to be regarded as a positive for occult blood. An absence of blue indicates
no detectable occult blood. These results should be read at room temperature (16-32C)
after 30 seconds and before 1 minute of pulling the tab. Within this time period, the
proper functioning of the reagents is indicated by the positive monitor turning blue;
should the monitor reaction be different, the test result is invalid. Contact Aerscher at
800 474 4072 for assistance if an invalid test result occurs. Color blind persons should
not interpret the results. Neither the intensity nor the shade of blue from the positive
Control Monitor should be used as a reference for the appearance of positive test results.
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Limitations of Test
Gastro-intestinal cancers, adenomas and ulcerations do not always bleed. Results cannot be
considered conclusive evidence of the presence or absence of GI bleeding or pathology, and
false positive or negative reactions are known to occur under certain circumstances such
as a person's diet, medication, or traumatic use of a nasogastric tube (see Patient
Preparation above). The test is not intended as a replacement for other diagnostic
procedures and further testing and examination by the physician such as
esophago-gastroscopy, sigmoidoscopy, barium enema, and imaging studies needs to be
performed to determine the exact cause and source of the occult blood.
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Expected Results
The use of guaiac impregnated paper for the detection of fecal occult blood has been
extensively studied and these clinical studies indicate that guaiac impregnated slide
tests yield a positive result 3-5% of the time in screening programs and the percent of
false positive results lies in the range of 1-2% of persons on a controlled diet
[8][9][10] , with the normal daily fecal blood loss in an adult lying in the range of 1-2
mls. of blood per 100 gram of stool [11]. Sensitivity(% of subjects with the condition
being sought who test positive) is difficult to estimate, but in series of patients with
known colorectal cancer, 50-87% have been reported to yield positive reactions[12][13][14]
Estimates of positive reactions with adenomatous bleeding have varied widely, and appear
dependant to a degree on the size of polyp, with polyps less than 2 cms yielding less than
5% positive reactions.[15]. The significance of gastric occult blood has been less
extensively studied than fecal occult blood. One study [17] of 153 gastric aspirates from
50 intubated healthy adults indicated all aspirates with more than 50 micrograms of
hemoglobin/ ml were positive. There was an apparent overall false positive rate of 25.5%
in this study of normal individuals, but even using less than 25 micrograms of hemoglobin
/ ml. as the test cut-off 11.8% showed a positive reaction. Another study [18] using 4
intubated healthy adults where blood was added to gastric juice, showed only positive
reactions when 200 or more micrograms of hemoglobin / ml. was present in gastric juice at
less than pH3. The false positive rate will obviously be affected by the test used and the
method of collection - use of a large naso-gastric tube is often seen to cause bleeding
initially. In practically all clinical situations where gastric juice is obtained, some
degree of bleeding might be expected. The false negative rate has not been established .
In anorther study [20] involving gastric samples from 10 patients and 10 healthy
volunteers gastric samples with HemaPromt, it was found that all samples with blood added
to produce concentrations of 0.1 mgHb/ml or greater reacted positively in pH ranges of 1
to 8.
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Performance Characteristics
Feces: Hemoglobin was diluted to the following concentrations: 1,2,4 and 6 mg/ml,
equivalent to 0.1, 0.2, 0.4 and 0. 6 grams hemoglobin per 100 grams of stool or
approximately 1,2,4 and 6 mls. of blood per 100 grams of stool. These dilutions were used
to test the sensitivity of HemaPrompt fg as well as to compare the reactions of one other
commercially available guaiac slide tests concurrently with HemaPrompt. In testing with
blood-spiked normal stool, HemaPrompt fg reacted positively at hemoglobin concentrations
of 2mg/ml or greater, in less than 60 seconds, with no reactions below this concentration.
Hydrating stool (unless dried by age) by adding distilled water may produce reactions
below this level by eluting blood out or the sample and onto the test paper and false
positive reactions are possible. Gastric Juice: The reactions of HemaPrompt fg to the
presence of blood in gastric juice were compared to one other commercial gastric occult
blood test, and tested in the following manner. Twenty batches of gastric juice obtained
by aspiration from different individuals, ten with gastric pathology and ten from healthy
volunteers. Each sample was divided into 5 further samples and the pH in each adjusted to
produce samples at pH 1.0, 2.5, 4.0, 6.0 and 8.0 respectively (simulating the varying pHs
likely to be encountered in gastric juices ). Each of these samples had blood added so as
to provide hemoglobin levels of 0.005, 0.01, 0.05, 0.1, 0.2, 0.5, and 1 mg hemoglobin / ml
Gastric juice - i.e. a total of 35 samples were available for testing,
reproducibility, and comparison to another commercially available product. These test
results showed excellent precision and reproducibility at all pH and blood levels. They
were performed 4 times the same day, and on three subsequent days on the same samples.
Levels of hemoglobin above 0.02 mg/ml gastric juice always produced a reaction in less
than 60 seconds and were negative below this level. Similar results were seen with to
another commercially available test designed for gastric occult blood and it was found
that this product reacted in a like manner. Furthermore, concentrations of ranitidine,
cimetidine, ferrous gluconate, and an antacid (Mylanta) to be expected in the stomach
after a maximum recommended dose did not alter the results. All monitors reacted in the
expected manner (+ve turned blue ). Exposing the guaiac paper to UV light for ten minutes
inactivated the expected reaction. It was concluded that with stool, HemaPrompt fg reacted
positively and definitely to all hemoglobin levels above 2mg/G of stool at which level
another commercially available guaiac slide test, when used in its indicated manner,
reacted comparatively and similarly. It was further concluded that with gastric juice,
HemaPrompt fg reacted positively and reliably to hemoglobin added to levels above 100mcg /
ml of gastric juice.
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WSLH Comparison Study
An independent comparison study was conducted by the WSLH Proficiency Testing Program.
HemaPrompt FG and Gastroccult (20 slides of each product) were used to compare sensitivity
to Hemoglobin in synthetic gastric juice (manufactured by WSLH Proficiency Testing ) over
a range of Hgb concentrations (500ug/ml minimum) and pH range 1 - 7.
No significant differences were found between the two products and each was found equally
suitable for the detection of Hemoglobin in gastric juice in the pH range of 1 to 7. (
September 2003)
Example
of Results
Negative
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Positive
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Positive
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Positive
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Negative
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Positive
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Positive
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Positive
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