Why is there no quality control at the pre-analytical phase?

Published 13.11.2015

Why is there no quality control
at the pre-analytical phase?

The majority of errors made during a laboratory process – up to 60% – occur at the pre-analytical stage, and only 20% at the analysis stage. However, while a great deal of information is being gathered on the quality of analytics, hardly any is collected on pre-analytics.

– A great deal of effort has been put into monitoring control samples at the analysis stage. At the same time, systematic monitoring of pre-analytics has been neglected, Professor Kerttu Irjala summarises.

Various variables

There are several potential sources of error at the pre-analytical stage. The first things to consider are biological background variables, such as eating and drinking prior to the test, which can have a significant effect on the final results. This is why proper instructions should be provided regarding these.

– If you’re taking a drug test and just happened to smoke some cannabis before your test, for example, you need to drink a lot, Irjala jokes.

There are also a few variables concerning sample collection, where the most typical source of error is a situation where the sample is being taken from the wrong patient.

In sample handling, errors may occur because of delays, for example.

Other background factors that may affect results are patient instructions and their availability, Irjala points out.

– A layperson does not understand our language. A lot more attention should be paid to this.

The physician requesting the tests also plays a significant role.

– Incorrect requests do occur and the test request menus may be poorly designed from a technical point of view. The options should not just be randomly ticked, however many clinics are using systems that are very user-unfriendly.

Did you go to the loo last night?

According to Irjala, where there’s a will to carry out systematic monitoring at the pre-analytical stage, there is also a way. The key to the solution lies in laboratory IT systems.

– There should be a feature enabling users to enter any deviations encountered at any stage of the process. All errors and sources of errors should be registered, for example if the patient has not fasted or has smoked before coming in for the sample collection or if they went to the bathroom the night before. I’m not sure who would confess to the last one, though, not me!

The stage of pregnancy should also always be registered.

– Using reference ranges that apply to those who are not pregnant for those who are is just crazy.

Any medication used by the patient as well as the time of day that the sample was collected should also be registered. The latter can effect testosterone levels, for example.

– Reference ranges refer to the values in the morning, however samples are still collected in the afternoon. There’s a decisive difference especially in young men, whose testosterone levels decrease significantly towards the afternoon.

Must I come back?

At the sample collection phase, the system should enable the user to register things like an incorrect sample site, sample contamination, incorrect storage or mixing as well as an incorrect tube.

– Contamination is common especially in urine samples, for women in particular. It’s not unheard of for men either. However, this is not taken into consideration when interpreting results.

Any delays between sample collection and analysis should also be registered, so that it can be considered when interpreting the results.

There’s room for improvement in the follow-up of the service as well. It would be especially important to register repeated tests.

– The number of times that the sample needs to be retaken is an extremely relevant piece of information.

Systematic monitoring

According to Irjala, systematic monitoring is the only way to gain genuine benefits and improve the process.

– Monitoring must be done continuously, on a daily basis. Different units must be compared as well. Laboratory IT providers can be asked for new solutions to enable this.

Solutions can be developed for monitoring clinical treatment as well.

– If the Kanta National Archive of Health Information is to evolve into a proper register at some point, it will also enable national comparisons for qualitative comparison of treatment. As laboratory professionals, we must also contribute to this development.

Text and photo: Hanna Hyvärinen

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