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How to do internal quality control in laboratory management?

How to do internal quality control in laboratory management?

  • Time of issue:2023-02-21
  • Views:

(Summary description)"Inspection quality is the lifeline of the laboratory department", this sentence is the most important sentence in the laboratory department of every hospital. How to ensure the quality of inspection requires the whole process of quality management, from before analysis, during analysis and after analysis, to manage the whole process , today we will talk about "indoor quality control of quality control in inspection".

How to do internal quality control in laboratory management?

(Summary description)"Inspection quality is the lifeline of the laboratory department", this sentence is the most important sentence in the laboratory department of every hospital. How to ensure the quality of inspection requires the whole process of quality management, from before analysis, during analysis and after analysis, to manage the whole process , today we will talk about "indoor quality control of quality control in inspection".

  • Categories:Blogs
  • Author:AIVD
  • Origin:
  • Time of issue:2023-02-21 10:09
  • Views:
Information

"Inspection quality is the lifeline of the laboratory department", this sentence is the most important sentence in the laboratory department of every hospital. How to ensure the quality of inspection requires the whole process of quality management, from before analysis, during analysis and after analysis, to manage the whole process , today we will talk about "indoor quality control of quality control in inspection".

 

 

1. Internal quality control and external quality assessment


Indoor quality control (IQC, internal quality control, referred to as "indoor quality control"): It is to use a stable substance to obtain a detection value of this substance on your detection system through repeated detection by yourself, and establish quality control through statistical methods Scope, to examine whether the test results are accurate and stable, determines whether the batch test is valid and whether the test report can be issued. That is, to objectively evaluate "stable or not".

 

External quality assessment (EQA, external quality assessment, referred to as "external quality assessment"): a stable substance is distributed to various laboratories, and the substance is tested with various instruments to obtain a set of test values. The acceptable range of detection value of the substance is obtained by statistical method. A quality control method for judging whether your test system is consistent with other test systems. That is, objectively evaluate "accurate or not".

 

 

2. How to conduct indoor quality control

 

2.1 Determining quality objectives


According to whether there is a measured value, it can be divided into fixed value quality control products and non-fixed value quality control products. According to the physical properties of quality control products, they are divided into freeze-dried quality control products, liquid quality control products and solid quality control products.


2.2 Setting target value and control limit

 

2.2.1 Quality control products with long stability

 

The laboratory should use its own current determination method to determine the target value of each item of the quality control product of the new batch number, and the fixed value quality control product and calibration value can only be used as a reference for determining the target value.

 

A provisional target value setting: According to the results of 20 quality control measurements (parallel determinations) for at least 20 days, calculate the average and standard deviation as the provisional target value and provisional standard deviation, and use the provisional target value and The standard deviation is used as the target value and standard of the next month's quality control chart for indoor quality control.

 

B. Establishment of commonly used target values: Repeat the operation process of A for 3 to 5 consecutive months, and calculate the cumulative mean and standard deviation from the first 20 data and all the data collected from the control data to 5 months, as the quality control Commonly used target values and commonly used standard deviations within the validity period of the product.

 

2.2.2 Quality control products with short stability

 

Within 3-4 days, analyze 3-4 bottles of each level of quality control product every day, and perform 2-3 repeated measurements on each bottle, calculate the average and standard deviation, and use it as the target value and standard deviation within the validity period of the quality control product.

 

Note: When the cumulative CV value is extremely small, please use it with caution. The general principle is that the CV value does not exceed the CV value of the clinical inspection center.

 

Replace quality control

When it is planned to replace the quality control product with a new batch number, it should be tested together with the "old" batch number quality control product before the end of use of the "old" batch number quality control product, and a new target value and control limit should be established.


2.3 Draw the quality control chart and record the quality control results

 

Draw a Levey-Jennings control chart (single concentration level) based on the target value and control limit of the quality control substance, or a Z-score chart that plots different concentration levels on the same chart, or a Youden chart. Record the raw QC results on the QC chart.


2.4 Handling and cause analysis of out-of-control situations

 

When the out-of-control signal is obtained, the following steps can be taken to find the cause:

 

2.4.1 Immediately re-assay the same quality control

 

This step is mainly used to find out the cause of the quality control by finding out the human error; in addition, this step can also find out the accidental error, if it is an accidental error, the result of the retest should be within the allowable range (in control). If the retest result is still not within the allowable range, you can proceed to the next step.

 

2.4.2 Open a new bottle of quality control product and retest out-of-control items

 

If the result of the newly opened quality control serum is normal, then the original bottle of quality control serum may be expired or left at room temperature for too long and deteriorate, or be contaminated. If the result is still not within the allowable range, proceed to the next step.

 

2.4.3 Perform instrument maintenance and retest out-of-control items

 

Check the status of the instrument, and perform cleaning and other maintenance on the instrument. In addition, the reagents should be checked, and the reagents can be replaced at this time to find out the cause. If the result is still not within the allowable range, proceed to the next step.

 

2.4.4 Recalibration, retest out of control items

 

Calibrate the instrument with a new calibration solution, and eliminate the cause of the calibration solution.

 

2.4.5 Asking for expert help

 

If the results under control cannot be obtained in the first five steps, it may be the cause of the instrument or reagent, and you can contact the instrument or reagent manufacturer to request their technical support.

 

 

3. How to pass the external quality assessment with high scores

 

  • Do a good job in indoor quality control to confirm the stability of the daily testing process and the accuracy of the results
  • Participate in external quality assessment projects organized by NCCL: CAP, UCLA, WHO and other governments and associations


If you follow the above requirements for long-term internal quality control to calibrate your testing process, congratulations, you can easily obtain the certificate of pass and full score.

 

 

4. How to select quality control products

 

Stable samples that are repeatedly measured in the internal quality control process are called quality controls. The International Federation of Clinical Chemistry and laboratory medicine (IFCC) defines quality controls as samples or solutions specifically used for quality control purposes. To select suitable indoor quality control products, the laboratory needs to pay attention to the following points:

 

4.1 Types of quality control materials

 

According to the source classification of quality control products, quality control products can be divided into supporting quality control products, third-party quality control products and self-made quality control products. Since third-party quality control products can provide clinical laboratories with unbiased evaluations, objectively reflect error levels, and are not limited to specific detection systems, international standards such as IOS15189 recommend that clinical laboratories give priority to third-party quality control products as internal quality control products. 

 

4.2 Matrix of quality controls

 

The purpose of indoor quality control is to ensure that the laboratory tests clinical samples correctly, so as to ensure that the test results are accurate and reliable. Only when the quality control product and the clinical sample have the same matrix, the quality control product and the clinical sample have the same performance during the test, and the quality control result can more closely reflect the real test quality. Therefore, ideal quality controls should have the same matrix as clinical samples.

 

IOS15189 medical laboratory quality and capability requirements stipulate that clinical laboratories should use quality control products that are as close as possible to patient samples in response to the detection system. Considering the matrix effect of quality control products is an important part of the indoor quality control program.

 

4.3 Stability of quality controls

 

Since the indoor quality control is based on the repeated measurement of stable quality control products and controls the precision of the detection system, stability is one of the most important performance indicators of quality control products. It is absolute that any quality control product changes and is unstable; it is relative if it does not change and is stable. Under normal circumstances, it is best for clinical laboratories to purchase the same batch of quality control products used throughout the year at one time to ensure the consistency of quality control results so as to effectively monitor changes in the detection system.

 

4.4 Difference between bottles of quality control products

 

The main purpose of indoor quality control in clinical laboratories is to control the repeatability and precision of the detection system, and one of the sources of variation in quality control results is the difference between bottles of quality control products themselves. Therefore, only when the difference between bottles is controlled to a minimum, the variation between test results can truly reflect the imprecision of daily test operations.

 

4.5 Concentration levels of quality controls

 

The clinical application value of the same test item at different concentrations is different, and when the test result is near the clinical decision value level, it may have a key impact on clinical decision-making. In order to ensure that the test results can be correctly used in the diagnosis and treatment of clinical patients, it is recommended that clinical laboratories consider whether their concentration levels are close to clinical decision values when selecting quality control products.

 

In the daily inspection work of clinical laboratories, if the indoor quality control only tests one level of quality control products, the reflected quality is the performance of only one point in the entire reportable range, and the quality control results of this point are under control, only Indicates that testing of patient samples is of satisfactory quality near this level control value, and does not necessarily reflect the quality of testing of higher or lower analytes farther from this point. Therefore, it is recommended that clinical laboratories select quality controls with at least 2 or 3 concentration levels.

 

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