False POSITIVES and True POSITIVES

Immunochromatographic methods are rapid qualitative methods in determining presence of specific antigens/antibodies in a given specimen. It provides a prompt diagnosis and is considered to be highly specific and sensitive.

During my shift this evening, I received a serum sample requesting us, laboratory technologists, to detect the presence of H. pylori antibodies. Being assigned to the section, I perform the test, and after 10 minutes, read it as POSITIVE.

Few minutes after, another serum was brought to the lab requesting for the same test. Again, I performed the procedure, and read it as POSITIVE.

"two positive H. pylori antibodies on the same shift? "  I said to my self and began doubting. Both results were held and should never be released not until controls and quality assurance were being met. I immediately run a negative control and just as I thought, the negative control gave  a POSITVE result.

Further investigations have led me to discover that the kit we used expired 10 days ago and was overlooked. I was relieved by the fact that both results were held and was not released immediately despite of the ordered urgency.

I opened a new kit and found out that the first serum was false positive while the latter was true positive.

The incident reminded me how man-made kits and technologies could betray us anytime. Any unsuspecting technologist might have been a victim of this. Our role (laboratory technologist) is to ensure that all results are valid and no machine could ever replace us.

LESSON LEARNED: (1) It pays to check the expiry dates on each reagent before using. (2)To ensure quality assurance, positive and negative controls should be run side by side with each test. (3) never release doubtful laboratory results.