5.2 Specimen Quality Assessment

5.2 Specimen Quality Assessment

Quick Answer: Inspect every specimen before and after centrifugation. Reject or flag hemolysis, clots in anticoagulant tubes, QNS, extreme lipemia/icterus, and IV-contaminated draws according to analyte-specific and lab policy. Document the problem and notify clinical staff—do not release results from a specimen you know is compromised.

Even with the correct tube type, a specimen can be analytically useless. Quality assessment is a core Domain II skill: the MLA is often the first person to see color, clarity, volume, and clot status after transport. Catching problems early protects patients from wrong potassiums, false CBCs, and delayed diagnosis.

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Visual Inspection: When and What to Look For

Before centrifugation

• Container integrity: cracks, leaking caps, open stoppers, grossly contaminated exterior.
• Volume vs fill line: especially light blue, pediatric microtubes, and blood culture bottles.
• Clots in anticoagulant tubes: tilt or gently rock EDTA/citrate/heparin tubes (without vigorous shaking) and look for fibrin strands or solid clots.
• Whole-blood appearance: extreme lipemia may already look milky; gross hemolysis may tint plasma layer if partially settled.
• Urine/fluids: clarity, color, unexpected stool/mucus, insufficient volume for ordered battery.

After centrifugation

Serum/plasma color and clarity become obvious:

Many chemistry analyzers also report serum indices (HIL: hemolysis, icterus, lipemia). The MLA still performs a human visual screen—indices confirm and grade what you flag, and some departments reject on visual gross hemolysis before loading.

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Hemolysis: Degrees and Affected Analytes

Hemolysis is rupture of red cells releasing hemoglobin and intracellular contents into serum/plasma.

Common causes (preanalytical)

• Traumatic stick, probing, small needle + large vacuum
• Vigorous shaking (vs gentle inversion)
• Drawing through hematoma
• Forcing blood through a needle into a tube
• Prolonged tourniquet, difficult draws
• Extreme temperatures during transport
• Delay before separation for some analytes

Analytes classically affected

Intracellular potassium is much higher than extracellular; even mild hemolysis can raise measured K+ into a critical false-high range. Other frequently elevated or altered analytes include LDH, AST, magnesium, phosphorus, iron, and sometimes troponin or other assays depending on method. Hemolysis can also dilute or interfere with spectrophotometric endpoints, lowering some results.

Exam focus: associate red/pink serum with hemolysis (not lipemia or icterus) and link hemolysis to falsely elevated potassium. Do not report a panic-high K+ from a grossly hemolyzed tube as a true patient emergency without quality review—follow critical-value and hemolysis policies together.

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Quantity Not Sufficient (QNS)

QNS means the volume is too small for the ordered tests (or for automatic reruns/reflexes).

• Pediatric tubes and capillary collections are high-risk for QNS.
• Multiple add-on orders on a single small SST commonly create QNS after primary testing.
• Blood cultures with inadequate fill reduce pathogen recovery—micro may reject or note limited sensitivity.

Actions:

1. Check whether priority tests can still be run on remaining volume (lab hierarchy / pathologist guidance).
2. Do not dilute the specimen with saline to “make volume” unless a specific validated procedure exists (rare for routine MLA workflow).
3. Request recollection for tests that cannot be completed; document QNS clearly so clinicians understand why results are missing.

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Clotted EDTA and Citrate Samples

Anticoagulant tubes must remain fluid and well mixed after collection (gentle inversions at the bedside).

Partial microclots are as dangerous as a solid plug—platelets and fibrin strands skew automated counts and coag endpoints. If you see clots, do not fish them out with an applicator stick and load the analyzer. Recollect with attention to immediate mixing, proper fill, and avoiding difficult traumatic sticks when possible.

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Lipemia and Icterus

Lipemia

• Look: milky, turbid, creamy layer.
• Cause: high triglycerides (non-fasting draw, IV lipids, metabolic disease).
• Effect: light-scatter and volume-displacement errors on many chemistry and some hematology optical methods.
• Lab handling: ultracentrifugation, lipid-clearing reagents, or method-specific dilutions per SOP; may still cancel some tests. Note non-fasting status when relevant.

Icterus

• Look: deep yellow to amber serum/plasma from bilirubin.
• Effect: spectral interference on colorimetric assays; degree-dependent cancellations possible.
• Note: icterus is often in vivo (patient disease), not a collection error—still may limit reporting. Do not confuse deep yellow icterus with hemolysis (red/pink) or lipemia (milky).

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IV Fluid Contamination Clues

Drawing above a running IV or failing to pause/discard properly contaminates blood with infusate.

Prevention belongs to collection technique (opposite arm, distal draw after pause). At processing, when results or appearance suggest dilution, escalate—do not quietly release. Recollection from a proper site is the usual fix.

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Document and Notify Per Protocol

Quality failures are incomplete until documented:

• Rejection or partial-cancel reason code (hemolyzed, clotted, QNS, lipemic, icteric, contaminated).
• Tests cancelled vs reported with comment.
• Who was notified (nurse, provider, unit clerk) and time.
• Recollection instructions if needed.

Follow your laboratory’s critical-result and problem-specimen SOPs. Some hemolyzed potassiums still trigger clinical calls after pathologist/tech review; others are cancelled without a critical alert because the result is artifactual—know which path your facility uses.

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Practical Bench Habits

1. Work under good light; use a white background to judge color.
2. Compare questionable tubes to a normal control tube when unsure.
3. Inspect gel barrier quality—incomplete separation or gel floating can indicate problems.
4. For urine, correlate dipstick vs appearance (e.g., red urine without RBCs suggests hemoglobin/myoglobin—clinical follow-up, not “normal”).
5. Never centrifuge a tube you already know is the wrong type or unlabeled—fix and labeling rules override quality cosmetics.

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Key Takeaways

• Hemolysis = pink/red; think K+, LDH, AST elevation and possible reject.
• Lipemia = milky; icterus = deep yellow—different interferences, different handling.
• Clotted EDTA/citrate and QNS → recollect; do not improvise.
• Visual checks happen pre- and post-spin; document and notify every time.