How should blood be collected for analysis after a tick bite? - briefly
Obtain a venous sample using aseptic technique, drawing blood into EDTA tubes for PCR detection of Borrelia DNA and serum tubes for serologic testing, with the initial draw as soon as possible after the bite and a repeat specimen 2–4 weeks later to assess seroconversion; label, store at 4 °C, and ship promptly to the laboratory.
How should blood be collected for analysis after a tick bite? - in detail
Collect the specimen using a sterile venipuncture technique. Begin with confirming patient identity and documenting the date and time of the bite. Apply a tourniquet, locate an appropriate vein, and disinfect the site with an approved antiseptic. Insert the needle at a 15‑30° angle, collect the required volume, and release the tourniquet promptly to minimize hemoconcentration.
Select tubes according to the intended analyses:
- Serum: Use a serum separator tube (SST) without additives for antibody detection (e.g., Lyme disease ELISA, immunoblot). Allow clotting for 30 minutes at room temperature, then centrifuge at 1,300–2,000 g for 10 minutes.
- Plasma: Use an EDTA tube for PCR assays targeting Borrelia, Anaplasma, Ehrlichia, or Babesia DNA. Mix gently by inversion 8–10 times to prevent clot formation.
- Whole blood: Use a heparinized tube if culture or flow cytometry is required.
Label each tube with patient name, medical record number, collection date, and specimen type. Record the exact time of draw, as timing influences serologic interpretation; acute-phase samples are typically obtained within 2–4 weeks post‑exposure, with a convalescent specimen 2–4 weeks later for seroconversion assessment.
Transport the specimens to the laboratory under temperature‑controlled conditions:
- Serum and plasma: keep at 2–8 °C if processing is delayed beyond 2 hours; avoid freezing before centrifugation.
- Whole blood for molecular testing: maintain at ambient temperature (15‑25 °C) and process within 24 hours.
Maintain a chain‑of‑custody log for any specimens destined for reference laboratories. Dispose of sharps in approved puncture‑resistant containers and follow institutional bio‑hazard protocols.
If multiple pathogens are suspected, consider drawing separate tubes for each test to prevent cross‑interference. Document any concurrent medications, especially anticoagulants, as they may affect test results. Ensure the patient remains seated for several minutes after the draw to reduce the risk of vasovagal reactions.