How to do a good job of internal quality control

How to do a good job of 

internal quality control


How to do a good job of internal quality control

According to the Ministry of Health Clinical Laboratory Center survey, there are currently 2.7% to 13.0% of adverse events in medical institutions is due to laboratory errors, in this case,internal quality control(IQC) is particularly important. Internal quality control is a series of inspection and control means adopted by laboratories to control the changes in precision and accuracy of laboratory tests through the daily determination of quality control products, monitoring and evaluating the quality of the work of the laboratory to determine whether the routine test report can be issued, including the whole process of laboratory work. It help to improve the consistency of the routine work of the laboratory batch to batch and day to day testing of the specimens. The most fundamental purpose is to ensure that the results are accurate and reliable, in order to provide diagnostic, diagnostic, and clinical services for the clinic. The most fundamental purpose is to ensure the accuracy and reliability of the results and provide the basis for clinical diagnosis, treatment and prognosis of disease.

There are several things that need to be done for good internal quality control:


Rigorous training of laboratory testing personnel

Before carrying out quality control, each laboratory testing personnel should have a full understanding of the importance of quality control, basic knowledge, the methods of quality control, and continuous training to enhance working capacity in the actual work of quality control. laboratory testing personnel should learn the correct operation of instruments and equipment, the correct use of reagents, the correct treatment of clinical samples, and understand the precautions during all operations. Only when all operations are carried out in accordance with the standard operating procedures, it is possible to ensure the accuracy of the tests and doing a good job of internal quality control.


Establishment of stable indoor quality control methods and standards

Each laboratory should establish its own Standard Operation Procedure (SOP). For example, the use of instruments, maintenance procedures, the use and preservation procedures of reagents, samples, calibrators and quality control products. The establishment of a complete standard operating procedures make it convenient for laboratory personnel to carry out standard training. All the operations of the laboratory personnel have a standard can be based on. The procedures avoid the operation of arbitrariness and reduce the operation of the experimental bias brought about by the operation.


Selection of reagents

Reagent quality is also a basic factor for good experiments, we should strictly control the quality of reagents and choose high quality and stable fresh reagents. We can not use expired products. We should know the properties of the reagents and the storage and use of reagents. The loss of control caused by unstable reagents should not be ignored. Record the date of each reconstitution of the reagent. Try not to re-dissolve reagents that have exceeded the stabilization time, and avoid mixing old and new reagents. In this way, loss of control due to reagent failure can be avoided.



Instruments for the determination of clinical samples should be calibrated according to certain requirements, and calibration requires the selection of appropriate (matching) calibrators; If possible, ensure that the results can be traced back to the reference method or/and the reference substance and the frequency of calibration should be established according to the characteristics of the different analytical items.


Selection of QCs

Control materials are the important material basis for quality control work. According to the properties of control materials, there are freeze-dried control materials, liquid control materials and mixed serum, etc. Depending on the presence or absence of measured values, they can be categorized into fixed-value and non-fixed-value control materials. Laboratories can choose one as internal control materials according to their own situation.

As an ideal control materials, it should have the following characteristics:

  • Human serum matrix;

  • Uniform distribution;

  • Non-infectious;

  • Low quantities of additives and modifiers;

  • Low inter-bottle variability;

  • Lyophilized product needs to be stabilized after reconstitution;

  • Valid for more than 1 year.

Do this consistently twice a day, with the specimen, including at least two different concentrations of control materials. There should be statistical parameters for control materials in the room, select the QC data of 20 consecutive days, calculate the mean value, SD value and coefficient of variation as the range of QC in the room, and draw the QC chart. There should not be 5 consecutive times of data on the same side of the mean value or 5 times of gradual increase and decrease, and there should not be two consecutive times of more than ± 2s.


Regular maintenance and calibration of instruments

Instruments need to be cleaned and maintained regularly and documented according to the instrument manufacturer's requirements. General-purpose measuring instruments, such as pipettes, should be calibrated annually. Understand the working principle of all kinds of instruments, know how to set the parameters of the instruments and the normal range of the items correctly, and read the contents of the manual carefully.


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WS /T 641-2018 临床检验定量测定室内质量控制 [S]. 中华人民共和国国家卫生健康委员会,2018.

戴雪娥,闫伟,霍方杰,宋光磊,李茗,付兆强.质控品储存方式对 NSE 检测质量的影响[J].检验医学,2023,38(2):175-178.

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