Specimens may require special handling or collection in order to be accurate. Pre-analytical errors can occur before, during, and after collection when these procedures are not followed exactly.
Blood cultures must be drawn under strict aseptic technique to prevent false positives. Every set of cultures has one aerobic and one anaerobic specimen, and more than one set of cultures are frequently taken to ensure against false negatives.
When using a Unopette®, collect the specimen with the pipette. Place a gloved finger over the reservoir and mix by inversion, then carefully squeeze the reservoir to mix the specimen.
To perform a microhematocrit, you must obtain blood in a capillary tube and spin in a microhematocrit centrifuge. The cells separate from the plasma in the tube and the tube is compared to a scale on the machine or portable scale to determine the patient's hematocrit.
Peripheral blood smears require a drop of blood on a slide that is spread across the slide using a spreader slide. When complete, the smear is a thin tongue or bullet shape, does not go to the edge of the slide, and is feathered.
Point-of-care tests are obtained and tested immediately at the point of care or near the patient. CLIA waived tests are performed in a certified laboratory, are FDA approved, and pose a minimal risk of harm to the patient. Strict regulations including frequent calibration of test machines is mandated.
A urine specimen can be collected from a catheter or from a patient using the clean-catch method. When dipped in urine, the reagent strip changes color to indicate the presence and/or concentration of a substance in a urine specimen.
When using a centrifuge make sure the load is balanced. If it makes noise turn it off immediately to prevent breakage. Wait until the centrifuge has stopped completely before opening and use a shield or mask, as required, when opening.
