Specimen Collection, Transport, Preservation, and Processing Flashcards

Flashcards covering pre-analytical specimen collection, venipuncture protocols, equipment, additives, urine, semen, body fluids, and processing guidelines.

What pre-analytical processes determine the integrity of clinical laboratory specimens?

Specimen collection, transportation, preservation, and processing.

How is a specimen defined in contrast to a sample in laboratory testing?

A specimen is the substance collected from a patient for analysis, whereas a sample is the specific portion of that specimen that is eventually subjected to analysis.

How is error defined within the clinical testing process?

Error is the discrepancy between the result obtained in the testing process and its True Value.

What three elements constitute a proper three-way match for in-patient identification?

Matching the information on the patient's ID bracelet, the test requisition form, and the patient stating their own name.

What are the three veins in the antecubital fossa listed in order of preference for venipuncture?

1. Median cubital, 2. Cephalic, 3. Basilic.

What four key components of the air-evacuated blood collection apparatus are labeled 1 through 4 in this diagram?

1. Double-Ended Needle, 2. Tube Holder, 3. Air-Evacuated Tube (Purple Top), 4. Assembled Vacutainer System.

Based on the Vacutainer blood collection system color coding, which tube colors correspond to EDTA, Citrate, Fluoride, Heparin, and SPS/ACD additives?

Purple top (EDTA), Blue top (Citrate), Grey top (Fluoride), Green top (Heparin), and Yellow top (SPS/ACD).

What angle of needle entry and anchoring technique are required during venous access in venipuncture?

The needle should enter at an angle of 15^\n\circ\text{ to }30^\circ depending on vein depth, centered over and aligned with the vein, while anchoring the vein to prevent movement and reduce pain.

What is a Serum Separator Tube (SST) and what internal components does it contain?

An SST is a collection tube with a gold or red/black speckled top containing a clot activator to induce blood clotting and an inert gel barrier that moves between serum and blood cells upon centrifugation.

Why must skin-cleansing alcohol be allowed to air dry completely prior to venipuncture?

To prevent hemolysis, which can cause spurious elevation of analytes such as potassium, lactate dehydrogenase (LDH), iron, phosphate, and magnesium.

Which skin disinfectant must be used when drawing blood for ethanol estimation, and why is povidone-iodine avoided?

Benzalkonium chloride solution must be used for ethanol estimation. Povidone-iodine is avoided because it interferes with most analytes.

What are the tourniquet application guidelines, and what occurs if tourniquet application exceeds one minute?

The tourniquet should be applied $3\text{ to }4\,\text{inches}$ above the site for no longer than $1\,\text{minute}$ ($60\,\text{seconds}$). Exceeding this time causes hemoconcentration, increasing serum protein, potassium, and lactate.

What biochemical alterations occur when a patient pumps their fist prior to venipuncture?

Fist pumping increases plasma potassium, phosphate, and lactate concentrations; the resulting decrease in blood pH causes ionized calcium to increase.

How does Heparin act as an anticoagulant in blood collection?

Heparin activates antithrombin III, which then forms complexes with activated coagulation factors IIa and Xa.

How does EDTA function as an anticoagulant, and for which assays is it unsuitable?

EDTA chelates calcium ions to form soluble calcium complexes, preserving cellular components; it is unsuitable for alkaline phosphatase (ALP), calcium, and iron assays.

How does Fluoride Oxalate function as a blood preservative and anticoagulant for glucose analysis?

Fluoride inhibits the enzyme enolase to stop glycolysis, while oxalate precipitates calcium into insoluble complexes to prevent clotting.

What effect does hemolysis have on plasma analyte concentrations?

Hemolysis causes a dilutional decrease in analytes present at lower concentrations in red blood cells than in plasma (sodium, chloride, calcium) and elevates analytes concentrated inside red blood cells (LDH, potassium, magnesium, phosphate).

What are the maximum depth specification and technique restriction for performing a skin puncture?

Puncture depth must be less than $2.5\,\text{mm}$ to avoid contact with bone. The finger should not be massaged, as massaging causes an outflow of tissue fluid and debris.

Why are evacuated tubes prohibited for arterial blood gas sampling, and how must drawn arterial samples be handled?

Evacuated tubes contain residual air. Drawn samples must have trapped air eliminated, be sealed, placed in a plastic bag with melting ice (to inhibit WBC metabolism, prevent pH changes, and stop gas expansion), and transported immediately.

What is a double-void urine specimen and what is its clinical purpose?

A specimen obtained by having the patient empty their bladder completely, discard that urine, and collect a second sample $30\text{ to }45\,\text{minutes}$ later; it assesses current metabolic activity, such as glucose excretion during a glucose tolerance test.

What procedure is required to collect a sterile urine sample from an indwelling catheter as illustrated?

Clamp the tubing below the sampling port for $15\text{ to }30\,\text{minutes}$, clean the port with an alcohol wipe, withdraw $10\text{ to }20\,\text{mL}$ of fresh urine using a sterile syringe/adapter, and transfer to a sterile container.

What are the required sexual abstinence duration, transit time, and transit temperature for semen specimen collection?

Abstinence: minimum of $2\,\text{days}$ ($48\,\text{hours}$) to a maximum of $7\,\text{days}$. Transit time: within $30\text{ to }60\,\text{minutes}$. Transit temperature: body temperature ($20^\circ\text{C}\text{ to }37^\circ\text{C}$).

What is semen liquefaction, and what is indicated if liquefaction is delayed beyond 60 minutes?

Liquefaction is the conversion of fresh gelatinous semen into a liquid state by prostatic enzymes ($15\text{ to }60\,\text{minutes}$). A delay beyond $60\,\text{minutes}$ indicates a prostatic enzyme deficiency.

How are CSF collection tubes allocated between laboratory sections during a lumbar puncture?

The first tube collected is used for chemical analysis, and the second tube is used for microbiological analysis.

How must amniotic fluid be stored when collected for lecithin-sphingomyelin ratio versus bilirubin assay?

For lecithin-sphingomyelin ratio, place immediately on ice. For bilirubin assay, transfer to a brown tube or wrap in aluminum foil to prevent photo-degradation.

Why is chorionic villus sampling (CVS) advantageous over amniocentesis for early fetal genetic testing?

CVS can be performed earlier, between $10\text{ and }12\,\text{weeks}$ of gestation, compared to weeks $15\text{ to }20$ for amniocentesis.

What three layers compose the packaging system required for long-distance transport of biohazardous specimens?

1. Primary receptacle (containing sample and absorbent material), 2. Secondary receptacle, 3. Tertiary receptacle (outer biohazard packaging box).

Why must blood specimen tubes be centrifuged with their stoppers in place?

To avoid aerosolization of infectious particles, maintain anaerobic conditions (vital for $CO_2$ and ionized calcium measurement), and reduce sample evaporation.

What is stated as the Golden Rule of Specimen Collection?

"The Patient's Test Result is Only as Good as the Specimen We Get."