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Time Constraints for Specimens

• Time constraints for specimens refer to the limited window of time within which samples must be collected, transported, and processed to ensure accurate and reliable test results.
• These constraints vary depending on the type of specimen, the tests to be performed, and the stability of analytes within the sample.
• Examples of time-sensitive tests include glucose, ionized calcium, LD or LDH, and potassium, which have a 2-hour limit.

Hematology Specimens

• Hematology specimens (EDTA) require:
  • Blood smears within an hour
  • CBC within 6 hours
  • ESR (EDTA) 4 hours at room temperature, and 12 hours in the fridge
• If blood is drawn in an SST/PST tube, it is stable for 24 hours after centrifugation and 48 hours if stored at 4°C.

Serum Specimens

• Once separated from the red blood cell, serum samples are stable at room temperature for 8 hours and up to 48 hours at 2-4°C.
• After 48 hours, serum specimens should be frozen at –20°C in an aliquot tube.

Molecular Testing Specimens

• Molecular testing specimens (RNA testing) should be transported, processed as soon as possible due to the instability of RNA substances.
• If not possible, they can be stored at 4°C for 48 hours, or frozen at –80°C in an aliquot tube.

Urine Specimens

• Urine specimens (C&S and UA) are dependent on timelines, as urine components change, and cellular elements decompose.
• Urine specimens can be tested within 2 hours at room temperature, or refrigerated if not possible.

Exceptions

• STAT and ASAP tests have different time constraints.
• Some anticoagulated tubes, such as sodium fluoride tubes for glucose and EDTA tubes, can keep blood stable for up to 24 hours at room temperature.
• Anything on ice should be processed immediately, and tissue specimens should be processed in microbiology immediately.

Aliquot Preparation

• Aliquot preparation refers to the process of dividing a larger volume of a specimen into smaller, standardized aliquots for storage, analysis, or distribution.
• Aliquoting is a common practice in laboratory settings to ensure sample integrity, facilitate efficient testing, and support future testing needs.

Post-Analysis Storage

• Anticoagulated venous specimens should be stored at 2–8°C if they will not be tested within 4 hours.
• Serum specimens should be separated from whole blood before being refrigerated.
• Specimens should be capped to minimize evaporation and contamination.

Rejecting Specimens

• Reasons for rejecting specimens include:
  • Clotted additive tubes or fibrin clots
  • Hemolysis
  • Lipemia
  • Specimens not protected from light
  • Specimens collected in the wrong tube
  • Unlabelled tubes
  • Not at body temperature
  • Chilling requirements not met
  • Contaminated specimen
  • Delay in processing
  • Wrong time, wrong tube, or wrong order

Disposal of Waste

• Dispose of laboratory waste in a safe and environmentally responsible manner.

Aliquotting

• Aliquotting involves transferring a portion of a specimen into one or more tubes labeled with the same ID information as the specimen tube.
• Each aliquot tube should be capped as soon as it is filled.
• Serum/plasma aliquots can remain at room temperature for no longer than 8 hours.

Temperature Considerations

• Temperature considerations in lab specimens are crucial to maintaining the integrity, stability, and quality of biological samples throughout the testing process.
• Different types of specimens require specific temperature conditions to preserve their characteristics and ensure accurate test results.

Protection from Light

• Some specimens, such as bilirubin, vitamin B12, and vitamin C, require protection from light to prevent degradation.

CSF

• CSF is used to diagnose meningitis infections and other brain disorders.
• This specimen is delivered STAT, and routine tests performed include cell counts, chloride, glucose, protein, and microbiology.
• Most tests require a minimum of 1 ml, and there are usually 3–4 tubes collected.

Transportation Off-Site

• The procedures for transporting specimens off-site involve several key steps to ensure the safe and timely delivery of samples to the testing facility while maintaining sample integrity.
• Transportation of Dangerous Goods Regulations (TDG) apply to the transportation of chemicals and specimens.

Phases of Laboratory Testing

• Laboratory testing involves three phases: pre-analytical, analytical, and post-analytical
• Pre-analytical phase includes sample collection, transportation, and processing
• Analytical phase includes laboratory analysis of samples
• Post-analytical phase includes result interpretation, reporting, and data management

Accessioning

• Accessioning is the process of receiving and processing specimens in the laboratory
• It involves verifying specimen integrity and labeling, assigning unique accession numbers, and entering patient and test information into the Laboratory Information System (LIS)

Distribution of Specimens

• Specimens are distributed to various departments, including Hematology, Clinical Chemistry, Blood Bank, Microbiology, Immunology/Serology, Coagulation, Urinalysis, and Send Out Dept
• STAT specimens should be delivered immediately and the technologist should be informed

Time Constraints for Specimens

• Molecular testing specimens (RNA testing) should be transported and processed as soon as possible due to the instability of RNA substances
• Urine specimens (C&S and UA) are dependent on timelines, and should be tested within 2 hours at room temperature or refrigerated
• Cytology specimens should be examined ASAP, and if not possible, ethanol should be added to preserve the cells

Aliquot Preparation

• Aliquot preparation involves dividing a larger volume of a specimen into smaller, standardized aliquots for storage, analysis, or distribution
• Aliquoting is done to ensure sample integrity, facilitate efficient testing, and support future testing needs

Sources of Preanalytical Errors

• Before collection: altitude, dehydration, duplicate test orders, exercise, not fasting, incomplete requisition, medication, patient stress, pregnancy, smoking
• At time of collection: misidentified patient, not letting the alcohol dry, expired tubes, not mixing properly, faulty technique, improper vein selection, incorrect order of draw, wrong tube, mislabeled tube, NSQ, wrong time, tourniquet left on too long
• During specimen transport: delay in transportation, agitation of specimen, exposure to light, wrong temperature, transport method (pneumatic tube vs. hand delivery)
• During specimen processing: contamination, delay in testing, delay in centrifugation, failure to centrifuge at the right speed, failure to separate the cells from fluid, mislabeling aliquot, multiple centrifugation, rimming clots
• During specimen storage: exposure to light, wrong temperature