Which of the following is NOT classified as a pre-analytical error?

Pre-analytical errors refer to mistakes that occur before the actual analysis of a sample, which can lead to inaccurate test results. In this context, the correct answer identifies an action that occurs after the sample collection or preparation process, which is referred to as a post-analytical error.

Transcription errors, which involve entering manual results incorrectly into the database or patient records, happen after the analysis has been completed. This means that while it does impact the interpretation and reporting of results, it does not affect the sample itself or its preparation; hence, it falls outside the scope of pre-analytical errors.

In contrast, the other options involve actions that take place before the analysis occurs. For example, ordering a test under the wrong patient number, misidentifying a patient, and mislabeling an add-on test all happen during the specimen collection, handling, or preparation phases and can lead to complications in diagnosing or treating a patient. Their impact is directly related to the integrity and accuracy of the sample prior to analysis, which is the key aspect of what defines a pre-analytical error.