A specimen is any biological sample collected for laboratory analysis, such as blood, urine, or tissue, which provides medical professionals with data to make a diagnosis or monitor a patient’s health. When a sample arrives at a clinical laboratory, it must meet strict quality and identification standards to be accepted for testing. Specimen rejection occurs when a sample is deemed unfit for analysis, meaning the laboratory cannot reliably perform the requested tests, often because the sample’s integrity or identity has been compromised. This rejection forces a delay in obtaining results and necessitates a repeat collection. The reasons for rejection are almost entirely due to errors that happen before the sample reaches the testing machine, known as pre-analytical errors.
Errors in Patient Identification and Labeling
The single most significant category of errors leading to specimen rejection is administrative failure during the collection process, specifically issues with patient identification and labeling. Errors like mislabeled, unlabeled, or partially labeled tubes are considered among the most dangerous types of pre-analytical mistakes because they introduce the risk of patient misidentification. Mislabeled specimens can lead to the wrong diagnosis or treatment, which is a major patient safety concern.
Improper labeling is considered a non-negotiable rejection criterion in most laboratories, as it is impossible to verify the sample’s true origin without a clear chain of custody. Patient misidentification errors have been reported to occur at rates ranging from 0.1% to 5% in various studies, and they are especially critical in areas like blood banking where a mismatch can be fatal. Another frequent administrative rejection cause is Quantity Not Sufficient (QNS), meaning the volume of sample collected is too small for the analyzer to process the requested tests. This often results from poor collection technique, forcing a recollection and adding to patient inconvenience.
Physical and Procedural Defects in Specimen Quality
Beyond identification issues, a substantial number of rejections stem from physical defects in the sample itself or procedural errors during collection and handling. One of the most frequent physical defects is hemolysis, which is the rupture of red blood cells (RBCs) and the release of their contents into the plasma or serum. Hemolysis makes the sample appear pink or red and is caused by poor phlebotomy technique, such as using too small of a needle or shaking the tube too vigorously during transport.
The release of intracellular contents, particularly potassium and lactate dehydrogenase (LDH), results in falsely elevated test values for these analytes. Hemolysis can also interfere with the chemical reactions used in many assays, leading to inaccurate results. Another common physical defect is clotting or the presence of fibrin in samples that require an anticoagulant, such as those used for hematology or coagulation testing. If the blood is not mixed immediately and gently with the tube’s additive, it will clot, rendering it unusable.
Improper container or additive usage is a common procedural error, such as using a plain tube when a specific anticoagulant, like EDTA or citrate, is required for a particular test. Improper storage or transport conditions can also degrade the sample’s integrity. Analytes within the sample can break down or change if exposed to extreme temperatures or if the time between collection and analysis is excessively long, ultimately leading to rejection.
Clinical Impact of Specimen Rejection
The rejection of a specimen has a direct impact on patient care and the efficiency of the healthcare system. The most immediate consequence is a diagnostic delay, as the laboratory cannot provide a result until a valid sample is processed. Specimen rejection resulted in a median processing delay of approximately 65 minutes, which can be a significant setback, especially for critically ill patients. This delay can postpone a physician’s ability to make a timely diagnosis and begin appropriate treatment.
Specimen rejection also leads to increased operational costs for the healthcare facility. These costs include wasted supplies, staff time spent identifying the error, communicating the rejection, and performing the recollection. One study quantified the average cost of recollection due to rejection at around $21.90 per specimen. For the patient, rejection means the discomfort and inconvenience of a repeat procedure, such as a second blood draw. The need for recollection also contributes to patient dissatisfaction and can prolong a hospital stay.