Parasite blood smear examination

TEST DESCRIPTION

Preparation and examination of thick and thin blood smears for bloodborne parasites, including Plasmodium (malaria), Babesia, and Trypanosoma species. Differential staining uses a modification of the classical Wright’s staining procedure.

Methodology

Microscopic examination of stained blood smear

Reference range

Negative (no blood parasites seen)

TEST FREQUENCY & RESULT AVAILABILITY

Performed daily. Results are typically available within one business day after specimen receipt.

ACCEPTABLE SPECIMEN TYPES AND COLLECTION

• Blood in EDTA tube (lavender-top)
• Thick and thin blood smears, 2 of each (stained or unstained)
  • Smears should be prepared as soon as possible after blood collection.
  • Unstained thin smears must be fixed or received by the laboratory within 4 hours of preparation (preferably within 1 hour).
    • To fix thin smears, dip the slide or completely submerge the smear area in 100% methanol for 30 seconds to 2 minutes. Remove from methanol, then allow to completely air dry.
  • Unstained thick smears must not be fixed.
• Collection instructions appear below

SPECIMEN STORAGE

• Blood in EDTA: store at room temperature (15–25°C/59–77°F) for up to 6 hours.
• Unstained smears (thick smear unfixed, thin smear fixed): store at room temperature (15–25°C/59–77°F) for up to 7 days.
• Stained smears: store at room temperature (15–25°C/59–77°F). Stained slides must demonstrate undistorted WBC and RBC morphology and have been prepared within 6 hours of blood collection.

SPECIMEN TRANSPORT

Shipping conditions should follow the temperature and time requirements outlined above.

REJECTION CRITERIA

• Hemolyzed specimens
• Blood in EDTA stored at refrigerated temperature
• Blood in EDTA stored for longer than 6 hours before thick and thin smears can be prepared
• Fewer than 2 thick and 2 thin blood smears
• Unstained thick (unfixed) and thin (fixed) blood smears stored for longer than 7 days prior to staining
• Thin smears that have not been fixed or stained within 4 hours of preparation
• Stained blood smears showing distorted WBC or RBC morphology
• Stained blood smears that were prepared more than 6 hours after blood collection

CODES

CPT: 87207

LOINC: 17784-0

Test code: 4040

TEST FEE

Refer to the current fee schedule.

SPECIMEN COLLECTION INSTRUCTIONS

1. Collect venous blood in an EDTA tube, with the draw date and time as well as the patient’s name marked on the tube.
2. Optional: Make a minimum of two (2) thick and two (2) thin smears as soon as possible or WITHIN 6 HOURS OF COLLECTION.
   1. Information on smear preparation may be found on the CDC DpDx website.
   2. Smears may be prepared from venous or capillary blood. 
   3. Unstained thin smears must be fixed with 100% methanol within 4 hours of preparation.
   4. Unstained thick smears must not be fixed.
   5. Stained smears (e.g., Giemsa) may also be submitted.