Point of Care Testing in Phlebotomy: POCT Basics

What Point of Care Testing Is

Point of care testing (POCT) is laboratory testing performed at or near the site of patient care rather than in a central laboratory. The results are available in minutes rather than the hour or more required for central lab processing. Bedside glucose meters, portable coagulation analyzers, and rapid strep tests are all examples of POCT.

POCT has expanded significantly in clinical settings because fast results drive faster clinical decisions. A patient in the emergency department with possible sepsis benefits from a blood gas result in 2 minutes, not 45. A patient adjusting their warfarin dose benefits from a bedside INR rather than waiting for a lab result to post.

Phlebotomists increasingly perform POCT in addition to traditional venipuncture, particularly in outpatient and clinic settings. The NHA CPT exam tests POCT basics including the types of tests available, CLIA classifications, quality control requirements, and the limitations of bedside testing.

Common POCT Tests

The following tests are routinely performed as POCT in clinical settings:

• Blood glucose — The most widely performed POCT. Handheld glucometers use a drop of capillary blood from a fingerstick. Results in under a minute. Used for diabetic monitoring and hypoglycemia detection.
• PT/INR (prothrombin time) — Tests anticoagulation status in patients on warfarin. Portable coagulation analyzers use fingerstick blood. Common in anticoagulation clinics.
• Hemoglobin and hematocrit — Portable devices assess anemia quickly. Used in blood donation settings and some clinical environments before procedures.
• Pregnancy (urine or blood hCG) — Lateral flow immunoassay. Rapid qualitative result. Used in emergency departments and clinics.
• Rapid strep A — Throat swab test for group A Streptococcus. Results in 5-10 minutes.
• Rapid influenza — Nasal swab detection of influenza A and B antigens. Results in 10-15 minutes.
• Urinalysis dipstick — Semi-quantitative analysis of urine for glucose, protein, blood, ketones, leukocytes, nitrites, pH, and specific gravity.
• Blood gases (ABG/VBG) — Portable blood gas analyzers provide pH, pO2, pCO2, bicarbonate, and electrolytes from small blood volumes. Common in critical care.
• Cardiac troponin — Rapid troponin assays help rule in or out myocardial infarction in the emergency department.
• Electrolytes — Sodium, potassium, chloride, and bicarbonate via portable analyzers. Common in critical care and dialysis settings.

CLIA and Test Complexity Categories

The Clinical Laboratory Improvement Amendments (CLIA) of 1988 regulate all laboratory testing performed on humans in the United States. CLIA classifies tests into three complexity categories based on the difficulty of performing the test and the potential for error:

Waived Tests

Waived tests are tests that are simple to perform, have a low risk of error, and pose an insignificant risk of harm to the patient if performed incorrectly. They are FDA-approved for home use or have been determined to be of low complexity.

Examples: blood glucose with approved meters, urine dipstick for certain analytes, rapid strep, rapid flu, qualitative pregnancy, fecal occult blood, spun hematocrit.

A CLIA certificate of waiver is all that is required to perform waived testing. No proficiency testing or personnel standards beyond following manufacturer instructions. Most POCT in physician offices and clinics falls in this category.

Moderate Complexity Tests

Most laboratory tests fall in this category. Performance requires more training, quality control is more rigorous, and CLIA sets specific personnel qualifications. Examples include many chemistry and hematology tests, some POCT devices, and most immunoassays that are not waived.

High Complexity Tests

Tests requiring significant judgment, interpretation, or technical skill. Includes most molecular testing, cytology, and complex microbiology. Highest level of CLIA oversight, most stringent personnel requirements.

For the NHA CPT exam, focus on knowing the waived category, what it means, and examples of waived POCT tests.

Quality Control in POCT

Quality control (QC) is one of the most heavily tested POCT topics on certification exams. QC verifies that the testing system is functioning correctly before results are reported on patient samples.

QC materials are solutions with known concentrations of the analyte being tested. When you run QC on a glucometer, you use a control solution with a defined glucose range. If the meter reads within that range, it is performing correctly. If the result is outside range, you do not report patient results until you identify and correct the problem.

QC Requirements for POCT

• Run QC at the frequency specified by your facility protocol and the manufacturer's instructions
• Typically includes at least a low and high control level (normal and abnormal ranges)
• Document all QC results with the date, time, control lot number, operator ID, and whether the result passed or failed
• Do not use a device that has failed QC to test patient samples until corrective action has been taken and QC passes
• Follow the manufacturer's instructions for reagent storage, expiration, and handling

Common reasons QC fails: expired reagents, reagent strips stored improperly (humidity, temperature), control solutions stored incorrectly, device malfunction, or operator technique errors.

Other QC Considerations

Reagent strips (for glucometers and urinalysis) must be stored according to manufacturer instructions. Most require storage in their original container with the cap sealed, away from light and moisture. Using strips from an opened bottle that was left uncapped or stored in a humid area can cause false results even when the strip is not expired.

Operator training and competency verification is required. POCT operators must demonstrate they can perform the test correctly and interpret results. This is especially important for waived tests, where the regulatory burden is lower but errors still cause patient harm.

Who Performs POCT

POCT is performed by a range of healthcare professionals depending on the setting:

• Phlebotomists (particularly in outpatient labs, clinics, and some hospital settings)
• Nurses and nursing aides (bedside glucose, urinalysis in inpatient units)
• Medical assistants (clinic settings)
• Respiratory therapists (blood gases in critical care)
• Emergency medical technicians (some pre-hospital settings)
• Physicians (some high-complexity POCT)

Each operator must be trained and have documented competency for each POCT device they use. Training is not transferable from one device to another without specific training on the new device.

Advantages of POCT

• Rapid results that accelerate clinical decision-making
• Small sample volumes (often a drop of capillary blood)
• No specimen transport time or handling requirements
• Convenient for patients who cannot travel to a central lab
• Reduces time-to-treatment in critical situations

Limitations of POCT

• Less accurate than central laboratory methods for most analytes
• Limited test menu compared to a full-service laboratory
• Highly operator-dependent: technique errors directly affect results
• QC and maintenance burden falls on non-laboratory personnel who may have less training
• Device-to-device variability: results from different glucometers may not be directly comparable
• Interference from hematocrit, medications, or sample quality can affect POCT accuracy

Hematocrit is a specific known interference for many glucometers. At very high or very low hematocrit levels, glucose results can be falsely elevated or depressed. Most modern meters have corrected algorithms for this, but it remains a documented limitation.

Practice Questions