Helping lab professionals GoMolecular.

Key Steps for Quality Control


In this article:

  • Six steps to molecular quality control
  • Valuable resources to help you keep up with quality issues



While most molecular tests involve unique technologies, the quality control (QC) principles and quality considerations are the same as other clinical lab disciplines. Molecular tests are subjected to the same Clinical Laboratory Improvement Amendments (CLIA) regulations as other highly complex laboratory tests. CLIA does not specifically mention a molecular subspecialty, but all the same rules and regulations need to be followed. There are some quality assurance challenges that are unique to molecular, and are different than chemistry and hematology.

“We see two types of lab directors that are particularly challenged when setting up a new molecular lab. One is a chemistry lab director with little molecular experience, the second is someone with a research background with little analytical QC experience,” said Joan Gordon, President, Maine Molecular Quality Controls, Inc.

No matter what your background, a lab director must become thoroughly familiar with molecular techniques and the associated quality assurance challenges. Here are six steps for quality control in the molecular lab.

1.    Plan Carefully
Before purchasing, developing or implementing any assay, you must think ahead and carefully plan for the possibilities. For example, amplicon contamination is unique to molecular. If you are considering a test where amplicon contamination is a possibility, be sure that the lab can accommodate the physical quality measures. It is pretty standard in molecular to have separate rooms, sometimes under positive or negative pressure, and unidirectional workflow.

“You must have the facility space for that test,” said Gordon. “If not, choose another test. If you go with closed systems, which are less open to contamination issues, then facility quality measures are not as important. It’s good to know in advance and plan for that.”

2.    Train Properly
Molecular lab personnel need to be trained in molecular techniques. The techniques are different from what they may be used to in chemistry or hematology.

In chemistry there are many controls and calibrators; in molecular there are very few. Many labs have to make their own QCs, and not all labs have the resources to do so. Your test vendor should be able to identify sources of QC for any test.

“You can purchase cell lines, but be careful. Not all cell lines have been characterized, and you can get the wrong answer. Then you are troubleshooting something that is difficult to understand,” warns Gordon.

According to Gordon, molecular technologists pipette very small volumes and they need to be very precise and mix carefully. Be sure to have well-calibrated pipettes available. Training webinars are quite popular and offer different aspects of molecular testing such as pipetting technique and other tips for lab directors and technicians. If training options are limited, choose assays with fewer steps that are simpler to run.

3.    Know the Risks
Before using a new assay, establish that the expected performance is sufficient for the intended use and conduct a risk analysis to ascertain where potential assay failures may occur. It will save time in the long run if you determine how the assay will be validated and monitored for performance. What controls are available to monitor the assay? Be prepared to spend some time locating reference materials and quality controls — they are not as easy to find as in other laboratory disciplines. Are proficiency samples available? Is there another lab you can work with? How will you track the data? Which data will be tracked? What are the risks? How many controls are needed? Where can the test fail? Is there software available to track and analyze control data? Ask yourself these questions and set up a plan in advance.

There may be a learning curve when starting out with QC practices in some molecular labs. “Lab directors who do not have a clinical chemistry background may not be familiar with plotting quality control results. They may not have the experience or the education for tracking the QC to identify shifts and trends that can be investigated and prevent failed runs,” said Gordon. She recommends learning how to apply statistical analysis in order to determine pass/ fail criteria, when they should they reject a run, and know when a control is truly out.

4.    Consider the Costs
Quality control for multiplex tests is an area where costs can be particularly challenging. Cystic fibrosis, for instance, is a 23-assay test system that will look for a minimum of 23 possible mutations. It is similar to an automated multi-analyte chemistry test. Chemistry panels for 23 analytes will have two to three levels of controls for each analyte, such as glucose, cholesterol, phosphorous, etc.

“Molecular labs can’t run that many controls for the 23 analytes,” Gordon said. “Economically it’s not possible to quality control in the same way. Labs need to get creative by rotating controls as frequently as possible, or by using or creating multiplex controls, keeping in mind the goal is to monitor every mutation on every run.”

Using good quality controls that reflect test performance, and checking for shifts and trends before a test fails, become particularly important when you are watching your budget. Repeating a failed run is an unexpected expense. Contamination prevention equipment, appropriate facilities and a comprehensive quality control plan are well worth the investment.

5.    Practice Prevention
It is wise to practice preventive quality control. Once you have contamination in the lab, it is very hard to get rid of. Better to plan for it and avoid it at all costs.

“If you have appropriate controls in place and tracking every time, running them routinely more than once a month, then you see trends happening. If you see a downward trend as an enzyme is getting ready to fail, you can swap them out or test a new kit before you have failure. That is really important,” said Gordon.

Preventive quality control can also mean construction in the lab. Things may need to be juggled around for unidirectional workflow. You may need to raise awareness about the use and placement of personal protection equipment, like lab coats and pipettes should stay in one area and not be moved to other areas.

“From the patient perspective, all lab results are important,” said Gordon. “If a patient is having a test for an inherited disease, those results affect the patient and the whole family. You need to get it right.”

6.    Stay Current
To stay current with quality issues in the molecular lab, lab directors and techs need to utilize various resources. Joining professional societies and networking is also important to stay up to speed with everything going on in the evolving field of molecular testing.

Quality is Key

Molecular testing and QC is still evolving, but keeping up with quality issues is crucial to the success of your lab. Even from state to state, the regulations and rules can vary. Be sure to utilize the resources above to keep your staff informed and regularly update your QC plan.

“Many patients are tested just once in a lifetime for a genetic marker, or perhaps the test has a direct impact on a chemotherapy course for cancer. The benefits of the extra time and extra cost for a comprehensive quality assurance plan far outweigh the risk of an incorrect result,” said Gordon.