Hihi to all. Sorry for the late posting as I couldnt log in due to the cookies. It is the 6th week of SIP, time really fly. For the past 6 weeks I been went to Processing, Biochemistry and Immunoassy Section. For the biochemistry and immunoassay section, all of the tests is done by analyser. While processing is understandable is to order entry
For this sharing, I will talk more about immunoassay section. I will be sharing some guideline on HIV screening & confirmation tests and BDvacutainer uses.
In the immunoassay section, the analyser use is the Architect ci2000. This machines uses the chemiluminescent microparticle immunoassay technololgy to determine the presence of Ag, Ab and analytes in the sample.
The BDVacutainer SystemCap Colour: Red
Additives: None
Effects on Specimen: Blood clots, and the serum is separated by centrifugation
Uses: Chemistries, Immunology and Serology, Blood Bank (Crossmatch)
Cap Colour: Gold
Additives: Separating gel and clot activator
Effects on Specimen: Serum separator tube (SST) contains a gel at the bottom to separate blood from serum on centrifugation
Uses: Serology, endocrine, immunology, including HIV
Cap Colour: Light green
Additives: Plasma Separating Tube (Na Heparin)
Effects on Specimen: Anticoagulants with lithium heparin; Plasma is separated with PST gel at the bottom of the tube
Uses: Chemistries
Cap Colour: Lavender/PurpleAdditives: EDTA (liquid form)
Effects on Specimen: Forms calcium salts to remove calcium to prevent clotting and platelet clumping
Uses: Hematology
Cap Colour: Light blue
Additives: Sodium citrate (Na Citrate)
Effects on Specimen: Forms calcium salts to remove calcium
Uses: Coagulation tests (PT, PTT)
Cap Colour: Dark green
Additives: Sodium heparin or lithium heparin
Effects on Specimen: Inactivates thrombin and thromboplastin
Uses: Ammonia, lactate, HLA typing
Cap Colour: Dark Blue
Additives: Sodium heparin
Effects on Specimen: Forms calcium salts. Tube is designed to contain no contaminating metals
Uses: Toxicology and trace element testing (zinc, copper, lead, mercury) and drug level testing
Cap Colour: Light Gray
Additives: Sodium fluoride and potassium oxalate
Effects on Specimen: Antiglycolytic agent preserves glucose
Uses: For lithium level, use sodium heparin. Glucose test.
Guideline to interpretation of result of HIV Screening and Western blot confirmation tests
HIV Screen: Non-reactive
Interpretation: A non-reactive HIV Ab screening test does not necessary exclude the possibility of infection with HIV. If exposure to HIV is suspected and thus serum is taken less than 3 months after this exposure, this should be retested after that time.
HIV Screen: Reactive
HIV Ab Confirmation: Negative
Interpretation: This result is commonly due to the presence of non-specific Ab, but occasionally may be seen in very early HIV infection. If exposure to HIV is suspected, 10ml blood in EDTA is send in 2-4 weeks time for repeat screening. For female patients in late pregnancy, the repeat sample is sent immediately.
(Rationale: HIV Ag is detected 1 to 2 weeks earlier than HIV Ab, thus making HIV screening test more sensitive than the western blot in the window period)
HIV Screen: Reactive
HIV Ab Confirmation: Indeterminate
Interpretation: This reactivity pattern commonly occurs in uninfected individuals due to the presence of non-specific Ab but may also be observed in early HIV infection. If exposure to HIV is suspected, 10ml blood in EDTA is send in 2-4 weeks time for repeat screening. Otherwise, another serum sample taken 6 weekslater will permit diagnosis in the majority cases.
Note: If a second sample is taken after 6 weeks and the western blot remain unchanged(still indeterminate), the following will be the interpretation applies:
- This indeterminate western blot profile has remain unchanged over 6 weeks. This may indicate a negative HIV Ab status associated with the lack of clinical signs and symptoms and/or supported by a negative history of exposure. If repeated exposure is suspected after the first sample is collected, send another sample for repeating screening.
HIV Screening: Reactive
HIV Ab Confirmation: Inconclusive
Interpretation: This is an indeterminate profile that include Ab to envelope and/or polymerase genes, which one often more sensitive indicators of earlu seroconversion. This profile may however also be due to non-specific Ab. 10ml blood in EDTA is send in 2-4weeks time to resolve the result.
HIV Screening: Reactive
HIV Ab Confirmation: Positive
Interpretation: Patient is consider HIV Ab positive
To confirm whether HIV positive or negative take a long procedure. And HIV Ab confirmation is negative does not mean negative too. As to test for HIV Ab confirmation take a period of time after exposure.
Feel free to ask qn but pls be mercy.
Juexiu Tg02