Specimen Collection Guides
Comprehensive guide to proper collection, packaging, and transportation protocols
Important Guidelines
Proper specimen collection is critical for accurate test results. Follow the specific requirements for each tube type, including mixing protocols, filling volumes, and processing times. Incorrect collection can lead to inaccurate results and may require sample recollection.
Red Cap
Plain / Clot Activator
Additive:
None or clot activator (silica)
Specimen:
Serum
Common Tests:
- •Serology (HIV, Hepatitis, VDRL)
- •Blood bank tests (crossmatch, antibody screening – if no gel)
- •Hormone assays
- •Drug levels
- •Chemistry tests requiring serum
Special Requirements:
- ⚠Allow blood to clot 20–30 minutes
- ⚠Centrifuge before testing
- ⚠Do not mix aggressively
Yellow Cap
SST – Serum Separator Tube
Additive:
Clot activator + gel separator
Specimen:
Serum
Common Tests:
- •Routine biochemistry
- •Lipid profile
- •Liver function tests (LFT)
- •Renal function tests (RFT)
- •Thyroid function tests (TFT)
Special Requirements:
- ⚠Allow complete clotting before centrifugation
- ⚠Gel forms a barrier between serum and cells
Purple / Lavender Cap
EDTA Tube
Additive:
EDTA (K₂ or K₃)
Specimen:
Whole blood
Common Tests:
- •Complete Blood Count (CBC / FBC)
- •Peripheral blood film
- •HbA1c
- •ESR (automated methods)
- •CD4 count
Special Requirements:
- ⚠Mix gently 8–10 inversions
- ⚠Do not centrifuge for CBC
- ⚠Prevent clotting immediately after collection
Black Cap
Sodium Citrate (3.8%)
Additive:
Sodium citrate (3.8%)
Specimen:
Whole blood
Common Tests:
- •ESR (Westergren method)
Special Requirements:
- ⚠Must be filled exactly to the mark
- ⚠Blood-to-anticoagulant ratio is critical
- ⚠Mix gently
Light Blue Cap
Sodium Citrate (3.2%)
Additive:
Sodium citrate (3.2%)
Specimen:
Plasma
Common Tests:
- •Coagulation studies:
- •PT / INR
- •APTT
- •D-dimer
- •Fibrinogen
- •Coagulation factor assays
Special Requirements:
- ⚠Fill tube completely (9:1 blood-to-citrate ratio)
- ⚠Mix gently 3–4 times
- ⚠Centrifuge promptly if plasma is needed
Green Cap
Heparin
Additive:
Heparin (Lithium or Sodium)
Specimen:
Plasma
Common Tests:
- •Electrolytes
- •Blood gases (if specified)
- •Ammonia
- •Some emergency chemistry tests
Special Requirements:
- ⚠Mix immediately to prevent clotting
- ⚠Not suitable for coagulation or blood bank tests
Grey Cap
Sodium Fluoride + Potassium Oxalate
Additive:
Sodium fluoride + Potassium oxalate
Specimen:
Plasma
Common Tests:
- •Fasting blood glucose
- •Random blood sugar
- •Oral glucose tolerance test (OGTT)
- •Lactate
Special Requirements:
- ⚠Inhibits glycolysis (prevents glucose breakdown)
- ⚠Mix gently after collection
- ⚠Ideal for delayed processing
White / Pearl Cap
EDTA + Gel Separator
Additive:
EDTA + gel separator
Specimen:
Plasma
Common Tests:
- •Specialized plasma tests requiring separation
Special Requirements:
- ⚠Mix gently after collection
- ⚠Centrifuge to separate plasma from cells
Blood Collection Tubes Visual Guide
A comprehensive visual reference guide showing all blood collection tubes, their additives, sample types, common uses, and the critical order of draw for proper specimen collection.
Important: Order of Draw
The order of draw shown in the infographic is critical for preventing cross-contamination between tubes. Always follow this sequence when collecting multiple tubes from a single venipuncture.
General Collection Guidelines
- •Always label tubes immediately after collection with patient information
- •Follow the correct order of draw to prevent cross-contamination
- •Store specimens at appropriate temperatures until transport
- •Transport specimens promptly to the laboratory
- •Contact the laboratory if you have questions about specific collection requirements