This screening test relies on the guaiac reaction wherein hemoglobin acts as a catalyst in the oxidation of a-guaiaconic acid by hydrogen peroxide.  The test is affected by the diet and medication status of the patient. Potential causes for false positive reactions include: oral iron supplements, rare or undercooked meat, fruits and vegetables high in peroxidase activity such as radishes, turnips, broccoli or cantaloupes.  Vitamin C in excess of 250mg/day may mask a positive reaction and appear to be negative.

Testing Protocol (condensed)

1.   Apply a thin smear of the sample into each test window.

2.   Turn card over and open back.

3.   Dispense two drops of the appropriate developer onto each test site.  Do not interchange the Gastroccult and Seraccult developers, Gastroccult is formulated to work in the acidic conditions of gastric content.  Seraccult developer will not react properly in low pH conditions.

4.   Interpret results within 60 seconds, the color may fade after 2-4 minutes.  Blue or any shade of blue is considered positive.

5.   Dispense a drop of developer on to the built-in QC.  Seraccult; Performance Control Line

      Gastrocult; Pos. Neg. dots.

      Do not report patient results if QC fails.

6.   Record the result in the patient's medical record.

 General Considerations

·Diet and medication status can affect the result.

·Use the correct developer with the correct card for the specimen to be tested.  Do not interchange.

·Always test the on-slide QC to demonstrate proper reactivity.

·Weekly QC requirements; record lot numbers and expiration dates for both slides and developers on the QC log sheet.

Quiz