Specimen Collection & Processing Flashcards

Which type of specimen typically requires transport on ice to preserve analyte integrity?

Answer: Ammonia, lactic acid, or arterial blood gas specimens

Ammonia, lactic acid, and arterial blood gases are labile analytes that continue to be metabolized by cells at room temperature; ice slows this process and preserves accurate results.

What does hemolysis in a blood sample indicate, and which test result is most critically affected?

Answer: Rupture of red blood cells; most critically affects potassium levels

Hemolysis releases intracellular contents (particularly potassium) from red blood cells into the serum, falsely elevating serum potassium and several other analytes.

What is the correct antiseptic used to prepare the skin site before drawing blood cultures?

Answer: Povidone-iodine or chlorhexidine gluconate scrub followed by 70% alcohol

Blood cultures require a two-step antiseptic preparation (povidone-iodine or chlorhexidine followed by alcohol) to reduce skin flora and minimize the risk of false-positive contamination.

What is the proper handling procedure for a urine culture specimen once collected?

Answer: Refrigerate at 2–8°C and process within 2 hours, or within 24 hours if refrigerated

Urine culture specimens must be refrigerated at 2–8°C to inhibit bacterial overgrowth; they should be processed within 2 hours at room temperature or within 24 hours if refrigerated to ensure accurate colony counts.

How many times should most anticoagulant blood tubes be gently inverted after collection, and why?

Answer: 8–10 times, to thoroughly mix the additive with blood

Gentle inversion 8–10 times ensures the anticoagulant or additive is evenly distributed throughout the blood sample without causing hemolysis from vigorous shaking.

What additive is found in gray top tubes, and what is it primarily used to test?

Answer: Sodium fluoride and potassium oxalate; glucose and blood alcohol levels

Gray top tubes contain sodium fluoride (glycolytic inhibitor) and potassium oxalate (anticoagulant), which together inhibit glucose metabolism, making them the standard choice for fasting glucose and forensic blood alcohol testing.

When collecting a 24-hour urine specimen, what should the patient do with the first morning void on day one?

Answer: Discard it and note the time, then collect all urine for the next 24 hours

The first morning void is discarded to establish a clean starting point (empty bladder at time zero); all urine produced over the next 24 hours, including the final void the following morning, is then collected.