Domain 6.3Point of Care Testing and Laboratory Procedures
Specialty Examinations
Last updated June 16, 2026
Overview
This guide covers specific diagnostic procedures often performed by Medical Assistants in specialty or primary care settings. These include vision and hearing screenings, dermatologic exams, allergy testing, pulmonary function tests, and TB skin testing.
1. Vision Screening
Key Tools
| Tool | Function | Key Details |
|---|---|---|
| Snellen Chart | Distance Acuity | Patient stands 20 feet away. Test one eye at a time (O.D./O.S.). |
| Jaeger Chart | Near Acuity | Patient holds chart 14-16 inches away. Screens for presbyopia. |
| Ishihara Test | Color Vision | Detects color blindness using colored dot plates. |
| Pelli-Robson Chart | Contrast Sensitivity | Uses fading letters (dark to pale) to detect low contrast issues (e.g., cataracts, macular degeneration). |
| Tonometer | Intraocular Pressure | Screens for Glaucoma. |
Documentation Abbreviations
- O.D. (Right Eye)
- O.S. (Left Eye - Sinister)
- O.U. (Both Eyes)
2. Hearing Screening
Tuning Fork Tests
- Weber Test: Fork placed on midline (top of head). Checks if sound is heard equally in both ears.
- Rinne Test: Compares Air Conduction (AC) vs. Bone Conduction (BC).
- Stem on Mastoid (Bone) -> Tines in front of ear (Air).
- Normal: Air conduction should be heard longer/better than bone.
Tympanometry
- Measures movement of the tympanic membrane (eardrum) to diagnose fluid in the middle ear.
3. Dermatologic Examination: Wood's Light
A Wood's Light (or Wood's Lamp) is a handheld device that uses UV light to detect bacterial or fungal skin infections.
- Preparation: The examination room must be completely dark.
- Procedure: The provider shines the light on the patient's skin.
- Interpretation: Infected areas (e.g., Ringworm/Tinea Capitis) will fluoresce (glow) under the light.
4. Allergy Testing
| Test | Purpose | Procedure Notes |
|---|---|---|
| Scratch (Prick) | Immediate reaction (pollen/dander) | Space sites 1.5 - 2 inches apart. Read in 15-20 mins. |
| Intradermal | Immediate reaction (more sensitive) | Injected into dermis. Read in 15-20 mins. |
| Patch Test | Delayed reaction (Contact dermatitis) | Patches worn for 48 hours. Keep dry. |
Reading Results (The Rule of 3 and 5): Always measure the Wheal (the raised bump), NOT the erythema (redness).
- < 3 mm: Negative Reaction
- 3 mm - 5 mm: Questionable/Moderate Reaction
- > 5 mm: Strongly Positive Reaction
5. Pulmonary Function Testing (Spirometry)
Spirometry measures the volume and speed of air exhaled to assess lung function.
Patient Coaching (Critical):
- No smoking 1 hour prior.
- Tight seal around mouthpiece.
- "Blow out HARD, FAST, and for at least 6 SECONDS."
6. Tuberculin (TB) Skin Testing
Also known as the Mantoux or PPD test.
- Injection: Intradermal (forearm).
- Reading Window: Patient must return in 48 to 72 hours (2 to 3 days).
- Interpretation: Measure the INDURATION (hard, raised area), not the redness.
7. Final Key Takeaways
- Snellen: Distance (20 ft). Jaeger: Near (14-16 in).
- Pelli-Robson: Contrast sensitivity (cataracts).
- Wood's Light: Dark room, check for fluorescence (fungus).
- Weber: Midline. Rinne: Air vs. Bone.
- Allergy: Measure the Wheal. >5mm is strongly positive.
- Spirometry: Requires a blast of air for 6 seconds.
- TB Test: Read within 48-72 hours. Measure induration.