The journey of a blood sample—from the moment it's collected to its analysis in a laboratory—is critical for ensuring accurate diagnostic results. The way blood samples are collected, transported, stored, and processed significantly impacts their viability and the integrity of the test results obtained.
For accurate analysis and test reliability, collecting the correct volume of blood is crucial:
Optimal Volume: Blood samples should be substantial enough to conduct two separate tests, either duplicate or distinct, of the intended analyses. Typically, blood draws collect approximately 2 to 2.5 times the required test volume, ensuring test repeatability and confirmation.
Waste Reduction: Although traditional blood draws often collect excess blood, much of which is ultimately discarded, dried blood testing generally requires much smaller volumes, minimizing waste and discomfort.
Proper labeling of blood samples, whether tubes, devices, or filter papers, ensures accurate tracking and identification:
Identification Methods: Samples can be labeled with pre-printed labels containing the individual's name and patient identification number or with unique barcodes incorporating the individual's pertinent information.
Home Collection: For at-home self-collected samples using finger-stick microsampling, it is essential to label the device or filter paper before it leaves the individual's possession to ensure proper matching and tracking.
Adhering to proper storage conditions is essential for maintaining sample integrity. Blood sample storage temperatures vary based on intended use:
Room Temperature: 15° to 30°C
Refrigerated: 2° to 10°C
Frozen: At or below -20°C
Blood samples intended for specific molecular genetic tests can remain stable for several days across varying temperatures. DNA, for instance, remains stable at room temperature for up to a month. Conversely, live blood cells begin losing viability within two days unless cultured or frozen using liquid nitrogen for prolonged storage.
Whole blood samples, commonly referred to as "wet blood," have limited shelf life:
Standard Shelf Life: Six weeks is typically the maximum shelf life for blood donations intended for transfusions.
Optimal Effectiveness: After three weeks, blood's efficiency in oxygen delivery significantly decreases, affecting its ability to navigate the smallest capillaries, especially if not properly refrigerated.
Flexibility and Viability: Blood stored unrefrigerated beyond three weeks permanently loses flexibility, underscoring the need for swift testing or appropriate storage methods such as refrigeration or freezing.
Specific guidelines outline the timeframe for processing wet blood samples:
Room Temperature Stability: Samples kept at room temperature (approximately +15°C to +30°C) must be analyzed within eight hours.
Refrigerated Storage: Samples stored between +2°C and +8°C remain viable for up to seven days.
Frozen Storage: If analysis occurs beyond seven days, samples must be frozen at temperatures between -15°C and -20°C.
Blood tests sometimes necessitate incorporating additives like anticoagulants, clot accelerators, or heparin. The specific additive used depends on the test specifications and significantly influences the testing and storage conditions of the sample.
Laboratory processing methods vary depending on the required analysis:
Whole Blood Analysis: Whole blood samples often require minimal preparation, possibly just dilution, for direct analysis.
Plasma and Serum Tests: Many tests require plasma or serum, obtained through centrifugation. Plasma, the liquid blood component, is separated from cells using anticoagulants, while serum results from blood clotting, leaving clear liquid for analysis.
Dried Blood Samples: Dried blood samples, collected from finger or heel sticks onto microsampling devices or dried blood spot (DBS) cards, undergo extraction processes tailored to the analysis requirements. Although capillary blood differs slightly from venous blood, dried capillary samples provide equivalent scientific and clinical results.
Technological advancements have significantly shortened the turnaround time for blood tests, with most results available within days. Once analyzed, lab technicians deliver the results electronically to the relevant healthcare professional, concluding the blood sample's journey.
Dried blood microsampling provides an innovative solution to traditional blood collection and storage issues:
Efficient Field Collection: Samples are easily collected and transported without specialized conditions.
Simplified Storage: Eliminates the need for refrigeration, reducing logistical complexities.
Enhanced DNA Longevity: Research indicates dried blood DNA remains viable for months, even under harsh conditions such as elevated temperatures or humidity.
Cost and Convenience: Reduces shipping costs, expands study participant pools, and facilitates remote sampling.
Microsampling represent the future of blood collection, providing practical, precise, and minimally invasive methods for gathering viable samples.
These technologies facilitate remote and simplified sample collection, offering robust alternatives to traditional blood draws, especially suitable for longitudinal studies and resource-limited environments.
In essence, proper handling, labeling, storage, and processing of blood samples are crucial for ensuring the reliability and accuracy of laboratory outcomes.
Adhering strictly to established guidelines guarantees sample integrity and optimal test results, promoting advancements in healthcare and research.
Sources:
https://labtestsonline.org/articles/laboratory-tour-blood%20sample