La recolección y el manejo adecuados de las muestras son parte integral para obtener un resultado de prueba de laboratorio válido y oportuno. Las muestras deben obtenerse en tubos o recipientes adecuados, etiquetarse correctamente y luego transportarse rápidamente al laboratorio.
Obtaining reliable and accurate laboratory test results
Physicians and others responsible for obtaining specimens and transporting them to the laboratory have a vital role in ensuring that laboratory test results are valid. The following are essential safeguards for your patients.
1. Avoid patient identification errors
Use at least two patient identifiers when administering medications, blood, or blood components.
Label containers used for blood and other specimens in the presence of the patient.
–Joint Commission National Patient Safety Goal 1, Elements of Performance, 2015.
Identify the patient prior to collecting a sample. Check armbands. Acceptable identifiers may include the patient’s full name, date of birth, or medical record number.
2. Dibuja los tubos en la secuencia adecuada
When multiple tubes are to be drawn from a single venipuncture using an evacuated tube system (e.g. BD Vacutainer® or Greiner Vacuette®), there is a correct sequence for blood collection that prevents cross-contamination of tube additives that could cause erroneous test results. The following should be used for both plastic and glass blood collection tubes.
The order of draw:
- Cultivo de sangre
- Coagulation tube (blue top) (1)
- Tubo de suero con o sin activador de coagulación, con o sin gel (tapa roja o dorada)
- Tubo de heparina con o sin separador de plasma en gel (tapa verde)
- EDTA (parte superior morada, parte superior rosa)
- Oxalato y flúor (tapa gris)
- Otros tubos especiales
(1) All blue tops collected for coagulation assays which do not have a blood culture collected first must have a discard tube collected prior to filling. Discard tube should be another blue top in which greater than 1 mL of blood is collected.
Todos los tubos deben invertirse suavemente 10 veces de extremo a extremo inmediatamente después de la recolección.
3. Utilice contenedores adecuados para la recogida.
Ciertos análisis requieren recipientes con conservantes y/o anticoagulantes, mientras que otros no. El uso del contenedor incorrecto a menudo conduce a resultados erróneos. Consulte el catálogo de pruebas para conocer los requisitos exactos.
4. Mezcle todos los tubos diez veces mediante una inversión suave inmediatamente después de la recolección
5. Do not decant specimens from one type of container into another
Specimens must be submitted to the laboratory in the container used originally for collection.
6. Deliver specimens to the laboratory promptly
Valid measurement of analytes in serum or plasma requires prompt separation from the blood cells. When left unseparated, analytes shift between the cells and the plasma or serum and glucose is consumed. Some analytes are unstable at room temperature. Drawing extra tubes of blood on patients and holding them as a contingency against some unforeseen need for more tests can lead to erroneous results and is a dangerous practice that should be avoided.
For specimens drawn off campus
Red and gold top tubes must stand for 30 minutes to allow for complete clotting. They must then be centrifuged and the serum separated and refrigerated until delivered to the laboratory. Check specific test information in the manual to determine if serum should be frozen.
Purple top tubes for CBCs may be kept at room temperature for up to 8 hours. After 8 hours, refrigerate until delivery. Stable 36 hours refrigerated. For tests drawn in purple top tubes other than CBCs, please check specific test stability.
Green top tube handling depends on the specific test ordered. Check specific test directions.
Laboratory specimen storage temperature requirements
| Storage Method | Centigrade (Celsius) Temperature Range |
| Refrigerated | 2 – 8 º C |
| Frozen | less than or equal to -20 º C |
| Room/ Ambient | 20 – 25 º C |
7. Evite la hemólisis
Erythrocytes contain certain analytes (LD, AST, K, ALT) in concentration many times higher than in plasma. When red cells are hemolyzed, there is a release of these analytes and dilution of plasma, resulting in erroneous laboratory values. Also, hemolysis may interfere in analytical methodologies.
8. Dibujar muestras de una línea
Si la muestra se va a extraer de una línea, asegúrese de extraer aproximadamente 5 a 10 ml para adultos en una primera jeringa de “lavado” (20 ml para eliminar cualquier heparina de la línea si se desean realizar pruebas de coagulación). A continuación, extraiga la jeringa para las pruebas deseadas. Si es necesario, se le puede devolver el “flush” al paciente.
