Biomedical Laboratory Science

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Showing posts with label Equipment. Show all posts
Showing posts with label Equipment. Show all posts

Saturday, March 17, 2018

Strategies for Preventing Amplicon Contamination in Molecular Laboratory !



The high sensitivity of the polymerase chain reaction (PCR)—theoretically with lower limits of detection as little as a single template molecule; practically, 10 to 100 copies for many assays as run—is one of its greatest strengths, but also its greatest weakness. As the method works through creating copies of its target, any positive sample can lead to large numbers of molecules which can in turn contaminate subsequent reactions and cause false positive results.


To get a sense of the scope of this, consider a successful “average” 25μl PCR somehow getting opened and spilled in the lab. This would contain on the order of 10^12 template copies (amplicons); in other words, if a thorough cleaning reduced this by a million fold, you’d still have a million amplicon copies “floating around,” each of which could contaminate a reaction. If you’re fortunate enough to have never experienced this first-hand, you can thank the widespread acceptance of real-time PCR methods, which do away with having to open reaction tubes post amplification, and perhaps gain an appreciation of why anyone who has been through the experience treats the risk as real and ever-present.


Thursday, November 3, 2016

Standardization And Implementation of Lab Policies Ensure Hemostasis Sample Quality

How many of us remember the tilt-tube method for basic hemostasis testing? Fortunately, today’s instruments have automated most of these manual steps. However, until recently, assuring sample quality in the pre-analytical phase of testing had remained a manual process and had been difficult to implement and standardize.

Several questions must be considered when evaluating the integrity of a hemostasis sample: Is the sample tube under-filled? Is the sample hemolyzed, icteric, or lipemic? If so, do the levels of the interferent impact the testing results? Is there a clot in the sample?

All labs have policies on sample acceptance and rejection. Inappropriate rejection of acceptable samples—requiring redraw—directly impacts patient care, patient satisfaction, and cost. Failing to reject inappropriate samples can lead to the reporting of erroneous results, impacting the quality of patient care and associated cost. Let’s take a look at the most common pre-analytical quality issue culprits.



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