How does guaiac test work?
Small samples of stool are placed on special cards coated with a chemical substance called guaiac and sent to a doctor or laboratory for testing. A testing solution is put on the cards and the guaiac causes the stool sample to change color. If there is blood in the stool, the color changes very quickly.
What is the principle of the guaiac FOBT?
Test is based on the oxidation of phenolic compounds present in the guaiac to quinones resulting in production of the blue color. When a fecal specimen containing occult blood is applied to the test paper, contact is made between hemoglobin and the guaiac.
What is the purpose of guaiac test?
The stool guaiac test looks for hidden (occult) blood in a stool sample. It can find blood even if you cannot see it yourself. It is the most common type of fecal occult blood test (FOBT). Guaiac is a substance from a plant that is used to coat the FOBT test cards.
What is the positive result in guaiac test?
Heme, a component of hemoglobin found in blood, catalyzes this reaction, giving a result in about two seconds. Therefore, a positive test result is one where there is a quick and intense blue color change of the film.
When is guaiac test used?
The guaiac fecal occult blood test (FOBT) is used to find occult blood (or blood that can’t be seen with the naked eye) in stool.
What is the difference between Hemoccult and guaiac?
Modern high- sensitivity forms of the guaiac test (such as Hemoccult Sensa) have much higher cancer and adenoma detection rates* than older tests (Hemoccult II and others). FITs also look for hidden blood in the stool, but these tests are specific for human blood and guaiac tests are not.
How should guaiac slide test be stored?
Store completed slides at controlled room temperature 15 – 30 degrees C (59-86F) in original packaging. Do not refrigerate of freeze. Protect from heat and light.
What does positive guaiac mean?
For the FOBT, a positive test result indicates that abnormal bleeding is occurring somewhere in the digestive tract.
What is guaiac in medical terminology?
: a test for blood in urine or feces using a reagent containing guaiacum that yields a blue color when blood is present — see hemoccult.
What type of diet is used for patient preparation for guaiac slide test?
Clinic staff must instruct the patient in the proper manner to label and prepare the slide before the patient collects the stool sample. A red-meat-free, high residue diet is recommended, starting two days before testing and continuing throughout the test period.
What is bloody stool called?
Overview. Gastrointestinal (GI) bleeding is usually categorized as either melena or hematochezia. Melena refers to black stools, while hematochezia refers to fresh, red blood in your stool. This blood might be mixed in with your stool or come out separately.