12.3 Waived Immunology, Serology, and Immunohematology Procedures
Key Takeaways
- AMT-named procedures include Strep A, HIV, RPR, RSV, influenza A and B, heterophile (mono) agglutination, rheumatoid-factor latex agglutination, and qualitative and quantitative pregnancy tests—perform only unmodified waived or point-of-care methods in CMLA scope (III.7.B.1).
- Strep A uses a throat swab; influenza A/B and RSV kits typically require the nasopharyngeal specimen the instructions for use name—throat and nasopharyngeal swabs are not interchangeable.
- A reactive waived HIV screen is preliminary and needs laboratory supplemental testing on the CDC-style algorithm; a reactive RPR is a nontreponemal screen and needs treponemal confirmation.
- Qualitative urine hCG is commonly CLIA-waived; quantitative serum hCG is often moderate or high complexity and is not a CMLA-independent assay.
- Read inside the labeled window; follow insert confirmatory language (strep culture or approved molecular testing when required) without modifying the kit.
AMT III.7.B.1 tells you to perform immunological, serological, and immunohematological procedures within the laboratory assistant’s scope of practice. Scope is unmodified waived and point-of-care (POC) methods the facility has implemented—not every immunoassay in the hospital send-out catalog. Named tests in III.7.A.1 are the exam list: Strep A test, HIV test, RPR test, RSV test, influenza A and B test, heterophile agglutination test (mono test), rheumatoid arthritis tests (latex agglutination), and qualitative and quantitative pregnancy tests. Chapter 5 already covered off-label use, timing, storage, throat versus nasopharyngeal (NP) as a specimen trap, and confirmatory names. This section applies those rules to this kit list without restaging the whole quality chapter.
Quick Answer: Run only the waived method in front of you, exactly as the instructions for use (IFU) are written. Strep A = throat. Influenza and RSV usually = NP, not a leftover throat swab. Read inside the window. HIV reactive is preliminary (laboratory supplemental algorithm). RPR reactive needs a treponemal confirmatory test. Qualitative urine hCG is commonly waived; quantitative serum hCG often is not. Do not issue blood as a “waived immunohematology procedure.”
Named kits: specimen, timing, and what the result is
The IFU of this lot always wins. Typical teaching patterns:
| Named test | What it detects | Usual waived specimen | Read-window idea | Confirmatory / next step |
|---|---|---|---|---|
| Strep A | Group A streptococcal antigen | Throat swab (tonsils/posterior pharynx) | Often minutes (for example, read at 5, not after 10)—use the insert | Negative screens, especially in children: culture or approved confirmatory molecular test when IFU/policy require it |
| Influenza A and B | Influenza A and B antigens (often separate lines) | Usually NP swab or aspirate | Labeled minutes; too late = ghost lines | Molecular influenza testing when the IFU or policy says to confirm |
| RSV | Respiratory syncytial virus antigen | Usually NP swab or wash (common in pediatrics) | Labeled minutes | Follow IFU; antigen sensitivity is limited |
| HIV | HIV antibodies and, on some 4th-generation devices, p24 antigen | Fingerstick whole blood, oral fluid, or other matrices the IFU lists | Device-specific; do not read a late window | Reactive = preliminary; laboratory supplemental algorithm—not a second waived pouch |
| RPR | Nontreponemal reagin antibodies (syphilis screen) | Serum or plasma as labeled | Rotator/read time per IFU if the method is in-scope | Reactive needs a treponemal confirmatory test (TP-PA, FTA-ABS, EIA/CIA) |
| Heterophile agglutination (mono) | Heterophile antibodies of infectious mononucleosis | Whole blood, serum, or plasma per IFU | Agglutination or cassette window as labeled | Does not by itself prove Epstein–Barr virus; send EBV-specific serology if clinically required |
| RA latex agglutination | Rheumatoid factor (RF), usually IgM | Often serum | Visible latex clumping in the labeled time | RF is not a standalone rheumatoid-arthritis diagnosis |
| Qualitative pregnancy | hCG present/absent | Commonly urine; some kits allow whole blood | Short window (often a few minutes) | Clinical correlation; order quantitative serum if the provider needs a number |
| Quantitative pregnancy | hCG concentration (mIU/mL) | Typically serum | Instrument method | Usually not waived; CMLA does not independently run it |
Traditional RPR on a rotator is often moderate complexity. Some rapid syphilis devices are waived, and not all of those are RPR. Perform RPR only when that method is waived or otherwise authorized for the assistant in the facility SOP. AMT still names RPR test, so you must know it is a nontreponemal screen and that a reactive result is not a confirmed syphilis diagnosis.
Throat versus NP, timing, and volume
AMT already used throat versus NP as the official wrong-specimen example (I.2.B.2). Apply it here:
- A Strep A kit that lists throat only does not accept the leftover influenza NP swab.
- An influenza A and B or RSV kit that lists NP only does not accept a throat swab from the strep workup.
- Do not rinse a dry swab with tap water, and do not dip a cassette into a transport medium the IFU forbids.
Read inside the labeled window. Too early misses a true line; too late produces evaporation lines. Insufficient specimen (Section 12.1) is the same invalid test as an expired pouch. Dual-swab when strep confirmation is required: one swab for the antigen cassette, one into transport for culture or molecular testing before you leave the patient. Do not try to wash a used antigen swab into a culture tube unless the IFU validates that swab for both.
HIV algorithm awareness (do not restage Chapter 5)
A waived rapid HIV result that is reactive is not a confirmed diagnosis. Current Centers for Disease Control and Prevention (CDC) laboratory testing starts with an HIV-1/2 antigen/antibody immunoassay, then an HIV-1/HIV-2 antibody differentiation immunoassay if the screen is reactive, then nucleic acid testing (NAT) if differentiation is negative or indeterminate. The CMLA job is: run the waived device per IFU, document preliminary reactive, protect privacy, and send the laboratory supplemental specimens the SOP names. Repeating the same waived pouch is not confirmation. Telling a patient “you are confirmed HIV-positive” from an oral-fluid stick is outside both the insert and assistant scope. Nonreactive waived screens still have window-period limits printed in the IFU—do not oversell a negative.
RPR needs confirmatory testing
Rapid plasma reagin (RPR) detects reagin antibodies against cardiolipin-like antigen, not Treponema pallidum itself. It is a nontreponemal screen. Pregnancy, some autoimmune diseases, and other infections can cause biologic false-positive RPR results. Very high antibody levels can cause a prozone false-negative RPR on some methods (Section 12.1)—another reason a CMLA does not invent dilutions on a waived device. A reactive RPR is not syphilis confirmed. Send a treponemal test (for example, T. pallidum particle agglutination, fluorescent treponemal antibody absorption, or a treponemal immunoassay). Do not treat RPR as the confirmatory method for HIV, mono, or pregnancy.
Strep, influenza, and RSV: confirmatory without repeating Chapter 5
Follow the insert, not hallway custom. Many Strep A IFUs still require culture or an approved confirmatory molecular test for negative antigen results in the intended population (classically symptomatic children). Influenza and RSV antigen tests have limited sensitivity; IFUs and facility policy often send selected results for molecular testing. Collect the extra swab or keep enough NP specimen so confirmation is possible. Culture workups, high-complexity molecular identification, and direct fluorescent antibody (DFA) reads are not independent CMLA testing (I.2.C).
Heterophile mono and rheumatoid-factor latex
The heterophile agglutination test (mono test) looks for heterophile antibodies associated with infectious mononucleosis. False negatives occur early, especially in young children; false positives occur. A negative mono test with high clinical suspicion is a send-out for EBV-specific antibodies, not a reason to incubate the cassette through lunch.
Rheumatoid arthritis tests (latex agglutination) detect rheumatoid factor. RF can be present in other inflammatory conditions and in some healthy older adults. Report reactive or nonreactive per IFU. Do not diagnose rheumatoid arthritis from a waived latex slide, and do not call the mono kit an RF test because both clump latex.
hCG: qualitative waived urine versus quantitative often not waived
Qualitative urine hCG cassettes are among the most common CLIA-waived serology tests. First-morning urine is more concentrated; very dilute urine and testing before missed menses can be false negative. Extremely high hCG can theoretically hook some immunoassays (antigen excess). Read only in the window; a late evaporation line is not a weak positive. Intended use is pregnancy detection in the labeled population—not a tumor-marker protocol you invent.
Quantitative serum hCG reports a number used for serial trends (viability, ectopic evaluation, some oncology protocols). Those immunoassays are typically moderate or high complexity. A CMLA does not convert urine-line darkness into a serum quantitative value, and does not independently operate the quantitative analyzer unless that specific method is waived—which it usually is not. If the provider wants a number, collect the serum tube the directory names and send it.
Immunohematology procedures still inside assistant scope
III.7.B.1 includes immunohematology, but Section 12.2 already drew the bright line: collect and label pink/lavender EDTA for type and screen; do not independently perform AHG crossmatches or issue units. If a facility ever uses a waived ABO grouping device for a non-transfusion purpose, it remains waived only if unmodified—and it still does not authorize hanging blood.
Scenario
A nurse hands you an NP swab and asks for Strep A, influenza A and B, and a “quick HIV.” The Strep A IFU lists throat only; the influenza IFU lists NP; the HIV device is waived for fingerstick whole blood, not a respiratory swab. You collect a throat swab for Strep A (plus a second swab if backup is required), run influenza on the NP specimen if it matches that IFU, and collect the fingerstick the HIV insert names. You do not “make one swab do all three.”
Exam traps
- Running an NP swab on a throat-only Strep A kit, or a throat swab on an NP-only flu/RSV kit.
- Calling a reactive waived HIV pouch a confirmed diagnosis.
- Treating RPR as treponemal confirmation, or as confirmation for HIV.
- Reporting quantitative hCG from urine-line intensity.
- Issuing O-negative blood as a waived immunohematology procedure.
- Reading cassettes after the stop time because a faint line “showed up later.”
Perform the named waived tests as written. Everything else on the outline is recognition, collection, and send-out—not a personal high-complexity license.
A waived Strep A kit lists throat swab as the only approved specimen. The collector submits a nasopharyngeal swab leftover from influenza testing. What should the CMLA do?
A waived rapid HIV test is reactive. What is the correct CMLA understanding?
Which statement about pregnancy testing and the other named waived kits is correct?