7.7 Point-of-Care Testing Procedures

7.7 Point-of-Care Testing Procedures

Point-of-Care Testing (POCT) Protocols

Point-of-Care Testing (POCT)—also known as bedside testing, near-patient testing, or decentralized testing—refers to diagnostic testing conducted at or near the site of patient care, outside the physical central laboratory.

                 POINT-OF-CARE TESTING (POCT) HIGHLIGHTS
  ┌────────────────────────────────────────────────────────────────────────┐
  │ CLINICAL ADVANTAGES:                                                   │
  │ • Drastically reduces Turnaround Time (TAT) from hours to minutes.     │
  │ • Enables rapid clinical triage and real-time medical interventions in │
  │   high-acuity settings (ED, ICU, Trauma Bay, Operating Room).         │
  │ • Requires minimal blood specimen volume (single capillary drop).     │
  ├────────────────────────────────────────────────────────────────────────┤
  │ COMMON POCT ANALYTES:                                                  │
  │ • Capillary Blood Glucose (bedside glucometers).                       │
  │ • Arterial / Venous Blood Gases (i-STAT, handheld analyzers).          │
  │ • Coagulation: Prothrombin Time / INR (CoaguChek).                     │
  │ • Cardiac Biomarkers: Rapid Troponin I / T, CK-MB, BNP.                │
  │ • Urinalysis: Automated dipstick chemistry and pregnancy (hCG).        │
  │ • Infectious Disease: Rapid Strep A, Influenza A/B, COVID-19 antigen.  │
  └────────────────────────────────────────────────────────────────────────┘

Standardized POCT Operating Workflow for Phlebotomists

1. Operator Identification & Barcode Security:
   • Phlebotomists must log into the POCT device using their unique operator ID badge barcode. Never share passwords or scan another staff member's badge; all testing actions are audited for quality and competency tracking.
2. Positive Patient Identification:
   • Scan the patient's hospital identification wristband barcode and verify two independent identifiers (full legal name and date of birth) verbally with the patient.
3. Quality Control Verification:
   • The operator must verify that daily liquid Quality Control (high and low levels) has been run and passed on the analyzer before testing patient specimens. Modern POCT devices feature electronic lockouts that prevent patient testing if QC is overdue or failing.
4. Reagent Integrity & Calibration:
   • Ensure test strips or micro-cuvettes are within their expiration date and stored in sealed, desiccant-lined vials at the manufacturer-specified temperature. Check that the strip lot code matches the meter's active calibration profile.
5. Specimen Collection & Application:
   • Perform skin puncture following CLSI standards (allow 70% alcohol to dry completely, wipe away the first drop of capillary blood to prevent interstitial fluid contamination, and apply the second drop smoothly to the test strip).
6. Infection Control & Instrument Disinfection:
   • Between every patient encounter, the POCT meter must be thoroughly wiped down and disinfected using an EPA-registered hospital disinfectant wipe (with required wet contact time) to prevent cross-contamination and healthcare-associated transmission of bloodborne pathogens (such as Hepatitis B virus).

What Makes Point-of-Care Testing Different

DTP task 3.13 is "perform point of care testing (e.g., urinalysis, glucose, pregnancy test)." Notice where it sits: in Domain 3, Specimen Collection — because POCT is something the technician performs, not merely something the laboratory does elsewhere. When you run a bedside glucose, you are simultaneously the collector, the analyst, and the person responsible for the quality of the result.

Common Point-of-Care Tests

• Blood glucose meters. The most frequently performed POCT. Use a capillary sample from a properly warmed, cleansed, and dried finger, and wipe away the first drop — residual interstitial fluid or alcohol will skew the reading.
• Urinalysis dipsticks. Timing is the whole method: each pad is read at its manufacturer-specified interval. Reading late produces false positives as reagents continue to react.
• Pregnancy testing (urine hCG). A first-morning specimen is the most concentrated and therefore most sensitive.
• Hemoglobin and hematocrit. Used for donor screening and anemia assessment.
• Point-of-care INR. Used for warfarin management; results are method-specific and not always interchangeable with laboratory INR.
• Rapid infectious disease tests. Strep, influenza, and similar antigen tests, where a negative result frequently requires confirmatory culture.
• Activated clotting time. Used during procedures requiring heparin monitoring.

Quality Control Obligations for POCT

The most common exam misconception is that "CLIA-waived" means "no rules." It does not. Waived status means the test is simple enough that the risk of an erroneous result is low when the manufacturer's instructions are followed exactly — and following them exactly is the obligation.

1. Run controls as the manufacturer specifies — typically at minimum with each new lot, each new shipment, when a new operator begins, if the device is dropped, and at defined intervals.
2. Document every QC result before patient testing. Undocumented QC is treated as QC never performed.
3. Do not test patients when QC is out of range. Investigate: expired or improperly stored strips, a device needing recalibration, or an environmental issue.
4. Check strip and reagent expiration dates and storage conditions. Test strips are humidity-sensitive; leaving a vial open degrades them.
5. Maintain operator competency records. Facilities must document that each operator was trained and periodically re-assessed.

[!WARNING] Never report a POCT result that contradicts the patient's clinical picture without confirmation. A glucose meter reading of 25 mg/dL on an alert, conversational patient is far more likely to be a meter or specimen problem than genuine profound hypoglycemia. Confirm with a laboratory glucose — and never simply re-run the same specimen on the same meter and accept the second number.

Documentation and Result Reporting

POCT results are patient results and belong in the medical record with the same elements as any other: patient identifiers, date, exact time, the result, the device or lot identification, and the operator. A result written on a paper towel and reported verbally is not documented. Critical values discovered by POCT follow the same critical-value notification process as laboratory results — immediate communication to the responsible clinician with read-back confirmation.