7.4 Preparing Non-Blood Specimens for the Lab
Key Takeaways
- Prepare urine with adequate volume, correct preservatives when ordered, and refrigeration (about 2°C–8°C) when testing will be delayed—especially for 24-hour collections.
- Transfer stool into appropriate fixative vials promptly and at the correct fill ratio for parasitology pathways.
- Handle AFB sputum in leak-proof containers with biohazard bagging and prompt microbiology delivery per TB precautions.
- Match swab transport media to the order—bacterial transport systems versus viral VTM/UTM are not interchangeable.
- Label the specimen container body (never lid-only), bag as biohazard, and verify requisition/order matching before dispatch.
7.4 Preparing Non-Blood Specimens for the Lab
Task 6.04 shifts from collecting non-blood samples to preparing them so the laboratory can accept and test them. Preparation includes verifying volume, applying the correct preservative or transport medium, refrigerating when required, labeling the container (not only the lid), matching the requisition, and bagging as biohazard material. Many rejections occur after a perfect collection instruction session because the handoff packaging failed.
Urine: Volume, Preservatives, and Refrigeration
| Urine Situation | Preparation Rule | Common Failure |
|---|---|---|
| Random / UA cup | Adequate volume for UA + possible reflex culture (often ≥10–12 mL when possible; follow SOP) | Nearly empty cup submitted “because patient tried” without noting QNS |
| Culture | Sterile container or urine culture preservative tube (e.g., boric acid gray-top urine tube) filled to fill-line | Nonsterile transfer; underfilled preservative tube |
| 24-hour collection | Verify entire timed volume, mix, measure/record total volume, aliquot per lab instructions; keep jug refrigerated or on ice during collection | Missing total volume on requisition; warm jug left on counter |
| Delayed testing | Refrigerate at about 2°C–8°C if analysis will exceed ~2 hours (or use approved preservative) | Room-temperature overnight urine with bacterial overgrowth |
For 24-hour urine, preparation is more than accepting the jug: confirm start/stop times, that the first void was discarded at start, that the ending void was included, and that any required acid/preservative was handled per chemistry instructions (some preservatives are pre-added and hazardous—do not dump or smell contents). Aliquot into labeled pour-off containers only after mixing the full collection so analytes are uniform.
Stool Fixatives
Parasitology and some GI pathogen pathways require immediate transfer into fixative vials (commonly dual-vial systems such as formalin and PVA, or newer single-vial fixatives per kit).
Preparation rules:
- Transfer the directed stool amount into each vial promptly; seat caps tightly.
- Do not overfill beyond the fill line—ratios matter for fixation.
- Keep patient instructions attached if dietary restrictions apply to companion occult-blood cards.
- Label vials with patient identifiers and collection date/time; place vials and requisition together.
Unfixed stool left warm for hours can destroy trophozoites and invalidate O&P examination even if the patient collected an excellent sample.
Sputum for AFB (Acid-Fast Bacilli)
Mycobacterial (AFB/TB) sputum handling emphasizes early morning deep specimens, sterile leak-proof containers, and prompt delivery.
Preparation / transport points:
- Verify the material looks like sputum, not saliva, when policy asks collectors to screen gross quality.
- Tighten lids to prevent leakage—AFB specimens are high-consequence biohazards.
- Bag as biohazard; follow facility rules for negative-pressure / TB transport pathways and do not leave cups on open counters.
- Deliver promptly; refrigeration may be used if delay is unavoidable per microbiology SOP—never incubate in a warm pocket.
Communicate to microbiology if the specimen is induced sputum versus expectorated, when that distinction is documented.
Swab Media: Bacterial vs Viral Transport
| Target | Typical Medium | Preparation Checkpoint |
|---|---|---|
| Bacterial culture | Bacterial transport swab/system appropriate to site (e.g., Amies) | Swab tip immersed/broken into medium per kit; do not let dry |
| Viral PCR / culture | Viral Transport Medium (VTM) / Universal Transport Medium (UTM) | Synthetic swab in VTM; avoid cotton/calcium alginate when prohibited for PCR |
| Wrong medium | e.g., dry swab for virus, or bacterial swab submitted for viral PCR | Lab rejection or false negatives |
Preparation means matching the order to the medium. A beautifully collected NP swab in the wrong tube is still a failed submission. Check expiration dates on media tubes before handing the kit to a patient or provider.
Label the Container—Not Only the Lid
Lids get swapped. Primary rule: place the permanent label on the specimen container body.
- Lid labeling alone is unacceptable.
- Labels must include patient name, second identifier, date/time, and specimen type/source when required (e.g., “clean-catch urine,” “wound—left shin”).
- Position labels so barcodes scan and volume windows remain visible when applicable.
+-------------------------------------------------------------------------+
| LID LABEL ONLY → HIGH MISID RISK IF LIDS EXCHANGED |
| CONTAINER BODY LABEL → REQUIRED SAFE PRACTICE |
+-------------------------------------------------------------------------+
Biohazard Bagging and Requisition Matching
Before leaving the collection area or receiving desk:
- Confirm requisition/electronic order matches every labeled container (name, MRN/DOB, tests, source).
- Place specimen in a leak-proof biohazard bag; put paperwork in the outer pouch (not soaked with specimen).
- Add ice packs or cold packs only when the analyte/SOP requires chilling—do not freeze urine solid unless directed.
- Flag special microbiology routes (AFB, viral) per courier rules.
- If anything mismatches (extra cup, missing label, wrong medium), stop and correct before dispatch—do not “send it anyway.”
| Hand-Off Check | Pass | Fail Example |
|---|---|---|
| Identity | Container label = requisition = order | Cup labeled, requisition for different patient |
| Medium | Matches ordered test | Dry swab for viral PCR |
| Volume / fill | Meets minimum or documented QNS pathway | Preservative tube far below fill line |
| Packaging | Biohazard bag, no leakage | Wet requisition fused to unlabeled lid |
Preparing non-blood specimens is the last chance to catch pre-analytical errors before they become resulting errors.
A 24-hour urine jug arrives for creatinine clearance. Which preparation step is essential before aliquoting for the chemistry bench?
A nasopharyngeal swab is ordered for influenza PCR. Which transport preparation is appropriate?
Why must non-blood specimen labels be placed on the container body rather than only on the lid?