Rapid self-test for detection of blood in faeces
General Points
Faecal blood can indicate different gastrointestinal disorders. These disorders can be as different as ulcers, polyps, colitis, fissures and colorectal cancer. These diseases cannot be detected only by visual examination and symptoms are often silent. Only the detection of blood in faeces can indicate a gastrointestinal disorder. Faecal occult blood in stool should be screened at least yearly starting by the age of 50.
The POLY-Check® is a manual qualitative immunochromatographic screening test for the detection of blood in faeces. It can be used at home by lay users for self-testing for the detection of colorectal abnormal bleeding disorders. The presence of blood in faeces only is not sufficient to diagnose cancerous lesions.
It is known that polyps are, in most of the cases for early stage of diseases, not bleeding all the time but only intermittently. Stool sampling must therefore be collected for three consecutive days to increase the probability to detect intermittent bleedings for safer patient information.
Test Procedure
Before performing the test, stool samples must be collected following the instructions below and be repeated during three (3) days:
A – Sample collection
First Day
1. Wash your hands with soap and rinse with clear water. Dry your hands with a clean towel.
2. The faeces are collect-ed on the special paper strip supplied in the box. ① Use one paper for each day.
3. The sample collection stick is attached to the white cap. Gently unscrew the white cap from the sample extraction solution, being careful not to spill any of the liquid. Next, insert the collection stick approximately 2 cm into the stool sample at three different areas.
Wipe away excess sample from the stick using a piece of toilet paper. Only the stool sample caught in the groove of the stick is needed.
②
Too much stool sample on the stick may block the flow of sample trough the test device and give an invalid result.
4. Put the white cap containing the faeces sample back in place onto the extraction solution. Screw it firmly and shake well to resuspend the faeces sample .③ Put the extraction solution vial back into the plastic bag and keep it in the refrigerator between each collection step.
5. Remove the collection paper strip and dispose it in the toilets.
Second Day
Repeat steps 1 to 5.
Third Day
Repeat steps 1 to 5.
B- Test realization after the 3 days collection period of samples
6. Tear the protective pouch (from the notch) and only get out the device. Discard the desiccant bag.
7. Wait for the extraction solution vial to be at room temperature before performing the test. Break the purple tip.④
8. Put the test device on a flat surface (a table for instance) and press the vial body to add exactly 5 drops of the extract with an interval of 2-3 seconds between each drop in the sample well.⑤
9. Read the result at 10 minutes. Do not interpret after 15 minutes.
Results Interpretation
The intensity of the line colour does not have any importance for the interpretation of the test result.
Analyze
Result
Summary
Positive result
Negative result
Invalid result
Questions and Answers
How does Poly-Check® work?
Gastro-intestinal lesions are often bleeding. The blood can be detected specifically by POLY-Check® in the faeces when concentration is higher than 10 ng/mL. The presence of blood can be explained by several causes: ulcers, haemorrhoids, colorectal cancer. The probability for intermittent bleeding to be detected is increased by the procedure of sample collection over 3 running days.
POLY-Check® test uses a pair of antibodies detecting specifically human haemoglobin by producing a coloured test line under the T mark of the cassette. A control line capturing the reagent excess appears as a coloured line under the C mark of the cassette. In case both lines appear, the test indicates that the level of haemoglobin is higher than normal (> 10 ng/mL determined against purified human haemoglobin material).
This procedure allows a more accurate test result for the patient especially for early stages of diseases and, therefore, greater probability to cure them.
When should the test be performed?
POLY-Check® test can be performed at any time of the day when having a bowel movement.
Can the result be incorrect?
The results are accurate as far as the instruc-tions are carefully respected. Nevertheless, the result can be falsified if POLY-Check® test gets wet before test performing or stool collecting steps are not correctly performed or if the sample is contaminated with blood from other origins than faeces (cuts, haemorrhoids, menses etc…), or if the room temperature is too high or if an incorrect number of drops is dispensed in the sample well.
How to interpret the test if the colour and the intensity of the lines are different?
The colour and intensity of the lines have no importance for result interpretation. The lines should only be homogenous and full. The test should be considered positive, whatever the colour intensity of the test line (T), even weak.
What is the line that appears under the mark C (Control) for?
When this line appears, it only means that the test performed correctly and that the test result is valid, but it does not play any role in result inter-pretation.
If I read the result after 15 minutes, will the result be reliable?
No. The test should be read 10 minutes after having adding the extract. The results are reliable up to 15 minutes.
What do I have to do if the result is positive?
If the result is positive, it means that blood has been detected in the stool sample and that you should consult a doctor to show the test results. Then, the doctor will decide what you have to do.
What do I have to do if the result is negative?
If the result is negative, it means that the test could not detect blood in stool sample. Meanwhile for the patients aged of 50 years and over or having relatives suffering from colorectal cancer, it is recommended to perform a test every year.
What is the accuracy of Poly-Check®?
The POLY-Check® test is accurate and has been used for more than 10 years by professionals in the field.
Evaluation reports show an overall agreement of 93% ([86.78 – 97.17*]) with different reference methods. Although this test is reliable, false positive or false negative results could be obtained. This is especially true for patients having medications like anti-platelet drugs which may show false positive results when using POLY-Check ® test.
*CI 95%: 95% confidence interval
Information on faecal occult blood and its clinical significance:
https://www.mayoclinic.org/tests-procedures/fecal-occult-blood-test/about/pac-20394112
https://medlineplus.gov/lab-tests/fecal-occult-blood-test-fobt/
https://www.biron.com/fr/centre-du-savoir/parole-de-specialiste/sang-dans-les-selles/
https://www.biron.com/en/education-center/specialist-advice/blood-in-the-stool/