Pre-Analytical Quality Control: The Foundation for Accurate Diagnosis

In modern medicine, laboratory test results are a key factor in helping physicians make accurate diagnoses and develop effective treatment plans. However, few people realize that the accuracy of these results depends greatly on the pre-analytical phase—the processes that take place before a specimen enters the laboratory. Strict control of specimen collection, storage, and fixation is not merely a technical requirement but a solid foundation for medical decision-making, directly affecting patient health. In particular, in pathology, the quality of specimens during the pre-analytical phase determines the ability to accurately diagnose histopathological and cytological conditions, including cancer.

1. Definition and Importance of the Pre-Analytical Phase

1.1. What Is the Pre-Analytical Phase?

The pre-analytical phase encompasses all activities from the time a physician orders a test until the specimen is ready for analysis in the laboratory [1, 7]. These steps include selecting the appropriate test, patient identification, specimen collection, initial processing, sorting, centrifugation, and specimen transport [1, 2, 4]. In pathology, this phase extends from obtaining tissue or cell specimens through biopsy or surgery to fixation, processing, and preparation for sectioning, staining, and microscopic examination.

1.2. Importance for Diagnosis and Treatment

The accuracy of laboratory test results is critically important for medical decision-making [3]. The pre-analytical phase is considered the stage of the testing process most vulnerable to errors [1, 7]. Errors at this stage can lead to inaccurate results, potentially affecting diagnosis, treatment, and patient safety [3]. In pathology, a suboptimal tissue specimen may result in an incorrect cancer diagnosis, inaccurate disease staging, or the inability to perform important immunohistochemical and molecular tests needed to guide targeted therapy [1, 5].

1.3. Rate of Errors in the Pre-Analytical Phase

Studies have shown that the majority of errors in laboratory medicine, ranging from 46% to 68.2%, occur during the pre-analytical phase, whereas analytical errors account for less than 10% [1]. One study conducted at a tertiary hospital found that pre-analytical errors accounted for approximately 1.48% of all specimens received [1]. Common errors included unlabeled specimens (35.8%), clotted blood samples (14.9%), diluted samples (11.8%), errors in medical records (10.2%), hemolyzed samples (9.7%), incorrect collection tubes (8.8%), and insufficient sample volume (8.8%) [3]. In pathology, common errors include inadequate fixation, insufficient clinical information, and tissue damage during specimen collection [1, 5].

2. Factors Affecting Specimen Quality During the Pre-Analytical Phase

2.1. Test Requests and Patient Preparation

Inappropriate test requests: Ordering unnecessary tests or failing to request necessary tests may affect diagnostic quality and costs [7]. In pathology, failure to request additional tests such as immunohistochemistry or molecular testing when indicated may delay or compromise the diagnostic process.
Patient preparation: Many tests require patients to fast or avoid certain activities. For biopsies, such as liver or kidney biopsies, adherence to instructions regarding fasting or temporary discontinuation of anticoagulant medications may be important for patient safety and specimen quality.
Medications: Certain medications may affect cellular morphology or the staining characteristics of tissue specimens.

2.2. Specimen Collection Techniques

Improper specimen collection techniques are a major source of pre-analytical errors [1].

Tissue Collection (Biopsy and Surgery)

Specimen size and site: The tissue sample should be sufficiently large and representative of the lesion to support accurate diagnosis. For tumors, sampling both the central and peripheral areas may be necessary for comprehensive assessment.
Avoiding mechanical damage: Specimens should be handled gently to prevent tissue crush artifacts and cellular or tissue distortion, which is particularly important when evaluating surgical margins or microscopic architecture.
Specimen orientation: Skin biopsies and oriented specimens should be clearly marked, for example with sutures or ink, so that the pathologist can properly orient and section the specimen [1].

Collection of Body Fluids (Urine, Cerebrospinal Fluid, Pleural Fluid, Bronchial Lavage Fluid, etc.)

Sterility: Appropriate sterile collection techniques should be used to prevent contamination, particularly for microbiological and fluid cytology testing.
Volume: A sufficient specimen volume should be collected for the required tests, including cytological examination, such as pleural fluid analysis for malignant cells.
Prompt processing: Cell-containing fluids, such as cerebrospinal fluid, should be transported rapidly to the laboratory and processed promptly to prevent cellular degeneration.

Cytology Smears (Pap Smears, Bone Marrow Smears, Smears From Skin Lesions)

Technique: Smears should be prepared using the appropriate technique to obtain an adequate number of representative cells and distribute them evenly on the slide, avoiding excessively thick or thin areas.
Prompt fixation: Cytology smears should be fixed immediately, for example with 95% ethanol or an appropriate cytological fixative, to prevent air-drying and preserve cellular morphology [3]. Improper fixation may distort cells and make cytological diagnosis more difficult.

2.3. Specimen Storage

Storage Temperature

Temperature is an important factor affecting specimen stability. For tissue specimens, after fixation, they are generally stored at room temperature in the appropriate fixative. CAP guidance emphasizes documenting appropriate fixation and storage conditions for surgical pathology specimens.

Anticoagulants and Stabilizing Solutions

Using the correct anticoagulant or stabilizing solution is essential. For tissue specimens, specialized preservation methods may be required for molecular testing when immediate fixation is not possible.

Storage Time

The interval between specimen collection and analysis should be carefully controlled. Excessively prolonged storage may lead to degradation of analytes or changes in the biochemical characteristics of the specimen [7]. For tissue specimens, cold ischemia time—the interval between tissue removal and fixation—should be minimized to preserve tissue architecture and molecular markers, which is particularly important for immunohistochemical and molecular testing in cancer diagnosis [1]. CAP guidance specifically recognizes cold ischemic time, fixative type, and fixation time as important pre-analytical factors affecting downstream testing.

2.4. Specimen Fixation (For Tissue and Cell Specimens)

Fixation of tissue and cell specimens is an important step in preserving cellular and tissue architecture, preventing degradation through autolysis and putrefaction, and preparing specimens for subsequent analyses, particularly pathology [1].

Types of Fixatives (Formalin, Ethanol, Carnoy's, etc.)

10% neutral buffered formalin: The most commonly used fixative for histology, suitable for most tissue types and routine testing, as well as many immunohistochemical and molecular applications. CAP guidance identifies 10% neutral buffered formalin as the recommended fixative for breast tissue specimens in relevant biomarker testing.
Ethanol: Commonly used for cytology specimens, such as Pap smears and fine-needle aspiration specimens, or when preservation of nucleic acids is required for genetic testing.
Carnoy's solution: Used for certain specialized tissues or research applications, particularly when rapid fixation and glycogen preservation or removal are required.

Fixation Time

Fixation time must be carefully controlled. Inadequate fixation—for example, when thick tissue specimens are not adequately penetrated by formalin—or excessive fixation may affect results. Smaller tissue specimens generally require less time for fixation than larger specimens. For relevant breast biomarker testing, CAP guidance specifies a recommended 6–72-hour fixation interval in 10% neutral buffered formalin.

Effects of Fixation on Analytical Quality

Improper fixation can alter cellular morphology, affect staining characteristics, reduce the quality of histological images, or interfere with immunohistochemical and molecular testing—for example, by reducing antigenicity or compromising DNA/RNA amplification [1, 5]. Pre-analytical factors such as cold ischemia time, fixative type and fixation time can affect nucleic acid recovery and downstream molecular testing.

2.5. Specimen Transport

Specimen transport should maintain appropriate temperature and conditions and avoid excessive agitation or direct exposure to light to preserve specimen quality [4]. The transport system should be designed to minimize transit time and ensure safety, particularly for specimens requiring urgent analysis or fresh tissue specimens that need immediate processing, such as specimens for frozen section examination.

3. Common Pre-Analytical Errors and Their Consequences

3.1. Errors in Test Requests and Patient Information

Incorrect test requests: Selecting the wrong test, omitting necessary tests, or ordering duplicate tests [7]. In pathology, failure to provide complete clinical information—including medical history, lesion site, and preliminary diagnosis—may make it difficult for the pathologist to reach an accurate diagnosis [1].
Patient identification errors: Collecting a specimen from the wrong patient or incorrectly labeling a specimen can lead to misdiagnosis and inappropriate treatment [1, 3, 7]. This is one of the most serious types of errors, particularly in cancer diagnosis, as it may potentially result in wrong-site surgery or treatment of the wrong patient.

3.2. Errors During Specimen Collection (Tissue Crush and Insufficient Volume)

Tissue crush artifact: Excessive manipulation of tissue during biopsy or surgery can damage tissue architecture, making microscopic assessment and diagnosis more difficult [1].
Insufficient volume: An inadequate specimen may not provide enough material for the required tests, resulting in repeat sampling, patient discomfort, and delayed results [3]. This is particularly important for small biopsy specimens, where insufficient tissue may prevent completion of all necessary diagnostic tests.

3.3. Errors in Storage and Transport (Inappropriate Temperature or Timing)

Inappropriate temperature: Storage at excessively high or low temperatures may alter specimen characteristics.
Prolonged transport or storage: This may cause analyte degradation, biochemical changes, or bacterial growth in the specimen [7]. For tissue specimens, prolonged cold ischemia may adversely affect nucleic acids and proteins, potentially affecting immunohistochemical and molecular test results [1].
Improper transport: Excessive vibration, light exposure, or physical impact may damage the specimen.

3.4. Errors in Fixation (Insufficient, Excessive, or Incorrect Fixative)

Inadequate fixation: Poorly preserved tissue may undergo cellular degradation, resulting in structural distortion and affecting histopathological diagnosis. Cells may rupture and nuclei may undergo morphological changes, making it more difficult to distinguish benign from malignant cells [1].
Overfixation: Excessive fixation may make tissue harder to process and section or reduce antigenicity for immunohistochemical testing, potentially compromising test reliability [1].
Incorrect fixative: Certain specialized tests, including some molecular assays, require specific specimen handling and fixation conditions. Using an inappropriate fixative may compromise the specimen and prevent the intended test from being performed [5].

3.5. Impact on Test Results and Patient Safety

Pre-analytical errors may result in:

Misdiagnosis or diagnostic delays, particularly in malignant diseases [1].
Inappropriate or unnecessary treatment, for example, when a cancer patient cannot receive targeted therapy because biomarker testing cannot be performed [1].
Increased healthcare costs due to repeat specimen collection, repeat testing, or inappropriate treatment [1].
Reduced patient confidence in healthcare services [1].
In serious cases, complications or death, for example, as a consequence of wrong-site surgery or inappropriate treatment [1].

4. Strategies to Improve Pre-Analytical Quality

4.1. Standardization of Procedures (SOPs)

Developing and adhering to detailed standard operating procedures (SOPs) for each step of the pre-analytical phase is fundamental. SOPs should include instructions for patient preparation, specimen collection techniques, tube or fixative selection, storage conditions, and transport [1, 7]. In pathology, SOPs should specify cold ischemia time, the volume and type of fixative, and specimen orientation [1]. Organizations such as the Clinical and Laboratory Standards Institute (CLSI) and ISO 15189 provide international guidance and standards relevant to laboratory quality management [6, 7].

4.2. Training and Competency Development for Healthcare Professionals

Human error accounts for a substantial proportion of pre-analytical errors [7]. Therefore, continuous training and competency development for all healthcare professionals—including clinicians, nurses, and specimen-collection personnel—are essential to reinforce the importance of the pre-analytical phase and correct techniques for specimen collection, handling, and storage [3, 7].
Training programs should cover professional knowledge, practical skills, and communication with patients. Particular emphasis should be placed on the proper handling of tissue and cell specimens for pathology, including accurate fixation and specimen orientation [1].

4.3. Application of Technology (Barcoding and Tracking Systems)

Barcode and automated identification systems: Using barcodes on specimen containers and electronically linking them with patient records can reduce identification and labeling errors [7]. Similar systems can be applied to tissue containers to ensure accurate tracking.
Laboratory Information System (LIS): Integrating the LIS with electronic test-ordering systems can help prevent data-entry errors and identify duplicate or inappropriate test requests [7]. The LIS can also track the specimen throughout its journey from collection to reporting.
Temperature monitoring devices: Data loggers or RFID technology can be used to monitor storage and transport conditions, which is particularly important for temperature-sensitive specimens [4, 7].

4.4. Continuous Quality Control and Performance Evaluation

Monitoring Quality Indicators (QIs): Laboratories should establish and monitor QIs for the pre-analytical phase, such as rates of hemolyzed specimens, clotted specimens, labeling errors, insufficient volume, cold ischemia time for tissue specimens, and inadequate fixation [7].
Root Cause Analysis (RCA): When an error is identified, RCA should be performed to determine its underlying causes and establish corrective measures [1].
Periodic performance evaluation: Regular assessment of the entire pre-analytical process helps identify and address problems in a timely manner [7].

4.5. Multidisciplinary Collaboration

Effective pre-analytical quality control requires close coordination among all relevant parties: clinicians who order tests and collect specimens; nurses and technicians who collect and initially process specimens; transport personnel; and laboratory and pathology staff who receive, process, and analyze specimens [1]. Effective communication and a shared understanding of the importance of each step are essential to ensuring quality. For example, clinicians should provide complete clinical information to pathologists, while pathologists should provide feedback regarding the quality of specimens received.

5. Benefits of Effective Pre-Analytical Quality Control

5.1. Improving Diagnostic Accuracy

Strict control of the pre-analytical phase helps preserve specimen integrity, thereby providing reliable material for analysis and supporting more accurate diagnoses [7]. In pathology, tissue that is properly collected, fixed, and processed enables pathologists to provide reliable histopathological and cytological diagnoses, including accurate classification and staging of cancer.

5.2. Reducing Errors and Healthcare Costs

Reducing specimen rejection rates and the need for repeat specimen collection and testing saves time and resources while lowering costs for both patients and the healthcare system [1, 7]. Pre-analytical errors may account for approximately 0.23% to 1.2% of a hospital's total operating budget [1]. Avoiding repeat biopsies or repeat surgery due to inadequate specimen quality also reduces the burden on patients and the healthcare system.

5.3. Improving Treatment Effectiveness and Patient Safety

Timely and accurate diagnosis supported by high-quality specimens enables physicians to develop effective treatment plans, reduce complications, and improve clinical outcomes. This also contributes to greater patient satisfaction and confidence in healthcare services [1]. In cancer care, accurate pathology diagnosis is fundamental to selecting appropriate treatment, including surgery, chemotherapy, radiotherapy, and targeted therapy.

6. Professional Consultation: Pathologist – Department of Pathology, University Medical Center Ho Chi Minh City

7. Frequently Asked Questions (FAQ)

What is the pre-analytical phase, and why is it important? The pre-analytical phase comprises all steps from the time a physician orders a test until the specimen is ready for analysis. It is critically important because it is one of the stages most vulnerable to errors, directly affecting the accuracy of test results and medical decision-making [1, 7]. In pathology, it is particularly important for ensuring the quality of histopathological and cytological diagnosis.
What are the common errors that can occur during the pre-analytical phase, particularly with pathology specimens? Common errors include patient identification and specimen labeling errors, improper collection techniques resulting in tissue crush or insufficient volume, inappropriate storage such as prolonged cold ischemia, and inadequate fixation of tissue or cell specimens, including insufficient formalin, excessive fixation, or use of an inappropriate fixative [1, 3, 7].
How do crushed tissue specimens or improper fixation affect pathology diagnosis? Crushed tissue can distort cellular and tissue architecture, making microscopic evaluation more difficult. Improper fixation can cause cellular disruption, nuclear changes, or loss of antigenicity, significantly affecting the ability to accurately diagnose disease, particularly cancer, and perform immunohistochemical testing [1, 5].
What should be considered when storing and transporting pathology specimens to ensure quality? Tissue specimens should be placed promptly in the appropriate fixative, such as 10% neutral buffered formalin when indicated, using an adequate volume, while keeping cold ischemia time as short as possible. Cytology specimens should be fixed promptly to prevent air-drying. Transport should avoid excessive agitation and maintain appropriate conditions to preserve specimen integrity [1, 7]. CAP guidance likewise emphasizes standardized tissue handling, documentation of ischemic and fixation times, and appropriate fixation conditions.
What international standards are used to control pre-analytical quality in pathology? Important standards and guidance include those from the Clinical and Laboratory Standards Institute (CLSI) and ISO 15189 (Medical Laboratories – Requirements for Quality and Competence), together with recommendations from specialized pathology organizations. These focus on standardizing the collection, fixation, processing, and handling of tissue and cell specimens [6, 7]. CAP also provides detailed guidance on surgical pathology specimen handling and fixation.

8. References

[1] Alavi, N., Khan, S. H., Saadia, A., & Naeem, T. (2020). Challenges in Preanalytical Phase of Laboratory Medicine: Rate of Blood Sample Nonconformity in a Tertiary Care Hospital. EJIFCC, 31(1), 21–27.
[2] Guder, W. G. (2014). History of the preanalytical phase: a personal view. Biochemia Medica, 24(1), 25–30.
[3] Tasneem, A., Zubair, M., Rasool, Z., & Tareen, F. Z. (2024). Frequency and types of pre-analytical errors in a clinical laboratory of a specialized healthcare hospital. Pakistan Journal of Medical Sciences, 40(2 ICON Suppl), S70–S74.
[4] Lippi, G., & Cadamuro, J. (2017). Novel Opportunities for Improving the Quality of Preanalytical Phase. A Glimpse to the Future? Journal of Medical Biochemistry, 36(4), 293–300. Accessed: December 10, 2025.
[5] Nordin, N., Ab Rahim, S. N., Wan Omar, W. F. A., Zulkarnain, S., Sinha, S., Kumar, S., & Haque, M. (2024). Preanalytical Errors in Clinical Laboratory Testing at a Glance: Source and Control Measures. Cureus, 16(3), e57243.
[6] Narayanan, S. (2001). Preanalytical Variables and Their Influence on the Quality of Laboratory Results. EJIFCC, 13(1), 9–12.
[7] Hawkins, R. (2012). Managing the Pre- and Post-analytical Phases of the Total Testing Process. Annals of Laboratory Medicine, 32(1), 5–16.

The information provided above is for reference purposes only and does not constitute a recommendation. Please consult a physician for detailed medical advice.