8.6 Processing Non-Blood Specimens & Routing to Laboratory Departments
Key Takeaways
- Hematology performs the CBC, differential, ESR, and coagulation studies in many facilities.
- Chemistry performs electrolytes, metabolic panels, enzymes, and therapeutic drug levels.
- Microbiology processes cultures and requires specimens in transport medium delivered promptly.
- Blood bank (immunohematology) performs type and screen and crossmatch and enforces the strictest identification rules.
- Urinalysis specimens should be tested within 2 hours or refrigerated, because delay changes cells, casts, and chemistry.
8.6 Processing Non-Blood Specimens & Routing to Laboratory Departments
Quick Answer: DTP tasks 3.19 (process standard non-blood specimens) and 3.22 (deliver specimens to the correct department) require you to know the laboratory's internal map. The Essential Knowledge Base lists "clinical laboratory departments" as an integrated concept for exactly this reason.
The Clinical Laboratory Departments
| Department | What it tests | Common specimens you deliver |
|---|---|---|
| Hematology | Formed elements of blood — cells and coagulation | Lavender EDTA (CBC, differential, ESR, HbA1c), light blue citrate (PT/INR, aPTT, D-dimer) |
| Chemistry | Analytes dissolved in serum or plasma | Gold SST and green heparin (metabolic panels, enzymes, lipids), gray (glucose tolerance, alcohol), plus most urine chemistry |
| Microbiology | Detection and identification of organisms | Blood culture bottles, urine cultures, throat and wound swabs, sputum, stool cultures, ova and parasites |
| Blood Bank / Immunohematology | Compatibility and antibody testing | Pink or lavender EDTA (type and screen, crossmatch, direct antiglobulin test) |
| Urinalysis | Physical, chemical, and microscopic urine examination | Random and first-morning urine |
| Serology / Immunology | Antigen and antibody testing | Serum for infectious disease serology, autoimmune panels |
| Histology / Cytology | Tissue and cell morphology | Tissue in fixative, Pap specimens, body fluids for cell analysis |
| Molecular / Reference send-out | PCR, genetics, esoteric assays | Specialized tubes per the reference laboratory's requirements |
[!IMPORTANT] Coagulation is sometimes a separate department rather than a hematology subsection, and serology is frequently folded into chemistry. Department boundaries vary between facilities, so learn your own laboratory's map. What does not vary is the principle: the specimen goes where the test is performed, promptly and in the required condition.
Why Routing Matters
Delivering a specimen to the wrong bench is not a harmless detour:
- Stability windows are consumed. A urine specimen that spends 90 minutes at the chemistry bench before reaching urinalysis may exceed the 2-hour limit for microscopic examination.
- Turnaround times slip, which matters most for the STAT specimens where turnaround was the point.
- Temperature-controlled specimens lose their condition. A chilled ammonia specimen routed to the wrong department warms while it waits.
- Blood bank specimens have the strictest handling of all, and a misrouted crossmatch specimen delays a transfusion.
Processing Standard Non-Blood Specimens
Urine
- Test or refrigerate within 2 hours. Left at room temperature, urine undergoes predictable deterioration: bacteria multiply, pH rises as urea converts to ammonia, glucose falls from bacterial and cellular consumption, ketones and bilirubin degrade, and casts and red cells lyse.
- Refrigeration preserves most analytes but can precipitate amorphous urates and phosphates, which obscure the microscopic examination.
- Chemical preservatives are used for timed collections; the preservative must match the test.
- For culture, deliver promptly or use a boric acid transport tube, which holds the bacterial count stable.
- Mix the specimen before aliquoting, because cells and casts settle.
Stool
- Ova and parasite specimens go into the specified preservative vials promptly.
- Culture specimens require prompt transport in a transport medium.
- Occult blood cards are handled per manufacturer instructions and are not refrigerated.
Sputum and Respiratory
- Transport promptly; refrigerate if delayed.
- Microbiology assesses specimen adequacy microscopically — a specimen that is mostly squamous epithelial cells is saliva and is rejected, which is why patient instruction matters so much.
Swabs and Cultures
- Place into transport medium immediately; a dried swab is a dead specimen.
- Deliver to microbiology promptly. Most bacterial transport media hold organisms viable at room temperature for a limited window.
- Anaerobic cultures require specific anaerobic transport systems and must not be exposed to air.
Body Fluids
Cerebrospinal fluid, synovial fluid, pleural, peritoneal, and pericardial fluids are typically collected in numbered sterile tubes distributed across departments — commonly tube 1 to chemistry or serology, tube 2 to microbiology, tube 3 to hematology for cell count. CSF is an irreplaceable specimen and is delivered immediately, never refrigerated when culture is ordered, and never delayed.
Transport Practices
- Secondary containment. Sealed biohazard bag with the requisition in the outer pocket, so a leak does not destroy the paperwork.
- Stopper up. Transport tubes vertically to promote complete clotting and prevent stopper contact, which causes hemolysis and aerosol on opening.
- Maintain the required condition end to end. Chilled specimens stay in the slurry; warmed specimens stay at 37 °C; light-protected specimens stay covered.
- Do not use pneumatic tube systems for specimens prone to hemolysis or where policy prohibits it — blood bank specimens, some coagulation studies, and manually collected syringe specimens are common exclusions.
- Hand off, do not abandon. A specimen left on a counter with no one notified is a specimen at risk. Delivery means transferred into the receiving department's process.
[!WARNING] A leaking specimen is both a biohazard and a compromised specimen. Do not attempt to salvage a leaking container by transferring the contents. Report it, decontaminate, and arrange recollection.
A random urine specimen for routine urinalysis sits at room temperature for four hours before testing. Which changes would be expected?
To which department is a light blue sodium citrate tube for a PT/INR normally delivered?
A cerebrospinal fluid specimen arrives in three numbered sterile tubes with cell count, chemistry, and culture ordered. What handling is appropriate?