Study guide
14.3 Microscopy Parts, Magnification, Wet Prep, and Cleaning
AMT Certified Medical Laboratory Assistant CMLA
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1 Introduction
1.1 Current Exam Facts 1.2 Blueprint Weights and Study Strategy
2 Chapter 2: Safety Terminology and Infection Control
2.1 Safety, Infection, and OSHA Terminology 2.2 Chain of Infection and Precautions 2.3 Isolation, Aseptic Technique, and Disease Prevention
3 Chapter 3: OSHA, HazCom, and Public-Health Reporting
3.1 OSHA Bloodborne Pathogens and Needlestick Safety 3.2 Hazard Communication, SDS, and GHS 3.3 Mandated Safety Rules and Public-Health Reporting
4 Chapter 4: Quality Assessment and Quality Control
4.1 Quality Control and Assessment Terminology 4.2 QC vs QA, Internal vs External QC, and Proficiency Testing 4.3 Daily QC, Temperature Logs, and Corrective Action 4.4 Instrument Maintenance and Calibration in CMLA Scope
5 Chapter 5: Waived-Test Integrity and Confirmatory Testing
5.1 Off-Label Waived Testing and High-Complexity Default 5.2 Following Manufacturer Instructions for Waived Tests 5.3 Confirmatory and Supplemental Testing
6 Chapter 6: Phlebotomy Foundations
6.1 Phlebotomy Terminology and Equipment 6.2 Serum, Plasma, Whole Blood, and Anticoagulation 6.3 Patient Identification and Container Identification
7 Chapter 7: Venipuncture, Order of Draw, and Specimen Integrity
7.1 Patient Preparation and Physiologic Effects 7.2 Vein Selection and Venipuncture Technique 7.3 Order of Draw and Tube Additives 7.4 Short Draws, Hemolysis, and Plasma-on-Cells Limits
8 Chapter 8: Capillary Collection, Processing, and Legal Specimens
8.1 Capillary Puncture Including Infants 8.2 Post-Care, Labeling, Transport, Processing, and Send-Outs 8.3 Specimens Used as Legal Evidence
9 Chapter 9: Non-Blood Collection and Preanalytical Errors
9.1 Urine Collection Types and Patient Instruction 9.2 Urine Suitability, Storage, Preservatives, and Rejection 9.3 Other Specimens and Time/Temperature Requirements 9.4 Shipping, Slide Prep, Preanalytical Errors, and Complications
10 Chapter 10: Clinical Chemistry
10.1 Clinical Chemistry Terminology and Test Families 10.2 Chemistry Instrumentation, Cleaning, and Maintenance 10.3 Point-of-Care and Waived Chemistry Testing 10.4 Toxicology Within CMLA Scope
11 Chapter 11: Hematology and Coagulation
11.1 Hematology Terminology, Blood Functions, and Cell Types 11.2 Hematology Instrumentation, QC, and Calibration 11.3 Coagulation: PT, PTT, INR, Heparin, and Warfarin 11.4 Point-of-Care and Waived Hematology Tests
12 Chapter 12: Immunology, Serology, and Immunohematology
12.1 Antigen-Antibody Principles 12.2 Blood Types, Rh, and Immunohematology Basics 12.3 Waived Immunology, Serology, and Immunohematology Procedures
13 Chapter 13: Microbiology
13.1 Microbiology Terminology and Specimen Appropriateness 13.2 Aseptic Processing, Storage, and Transport of Micro Specimens 13.3 Media, Cultures, and Procedure Matching 13.4 Stains, KOH, Wet Preps, Reagents, and Controls
14 Chapter 14: Urinalysis and Microscopy
14.1 Urinalysis Terminology 14.2 Waived Urinalysis Procedures and Specimen Handling 14.3 Microscopy Parts, Magnification, Wet Prep, and Cleaning
15 Chapter 15: Basic Anatomy and Physiology
15.1 Anatomy Relevant to Laboratory Testing 15.2 Physiology Relevant to Laboratory Testing
16 Chapter 16: Legal, Ethical, and HIPAA Foundations
16.1 Consent, ABN, Test Ordering, and PPM Restrictions 16.2 Patient's Bill of Rights, Refusal, and Medicolegal Risk 16.3 Professional Appearance, Conduct, and Social Media 16.4 HIPAA Confidentiality and Record Release
17 Chapter 17: Clerical Skills, Communication, and Critical Values
17.1 Reports, Abnormal Results, and Critical-Value Notification 17.2 HIT Data, Inventory, Expirations, and Billing/Coding 17.3 Patient Instruction, Communication, Telephone, and Time Management
14.3 Microscopy Parts, Magnification, Wet Prep, and Cleaning
Key Takeaways Explain This Topic AI
Total magnification equals ocular times objective; a 10× ocular with a 40× objective is 400×, not 50× (AMT III.9.C.1).
Immersion oil is used only with the 100× oil-immersion objective; never oil the 40× high-dry lens used to count urine cells.
Scan urine sediment for casts on 10× (100× total) and identify cells, organisms, and crystals on 40×; use coarse adjustment on low power only.
CLIA provider-performed microscopy (PPM, 42 CFR 493.19) is restricted to providers; a CMLA must not independently sign out wet mounts, KOH, fern, or pinworm.
Clean objectives with lens paper, wipe oil off the 100× the same day, and never drag the 40× objective through leftover oil.
Last updated: August 2026
AMT III.9.C requires microscopy terminology , microscopic urinalysis procedures within the laboratory assistant’s scope , and general cleaning of the microscope . III.9.B.2 adds prepare slides for microscopic examination . CLIA provider-performed microscopy (PPM) (42 CFR 493.19) is a moderate-complexity subset restricted to providers . A CMLA may prepare slides and perform sediment microscopy only when the laboratory’s certificate, SOP, and competency checklist authorize that assistant-level work. A CMLA must not independently sign out PPM procedures .
Quick Answer: Total magnification = ocular × objective. A typical ocular is 10× . Scan casts on 10× ; count cells on 40× high dry. Immersion oil belongs only on the 100× oil objective—never on 40×. Light travels lamp → diaphragm → condenser → specimen on the stage → objective → ocular . PPM (wet mounts, KOH, fern, pinworm, and the rest of the federal list) is provider work. Clean optics with lens paper; wipe oil off the same day.
Parts you must name
- Part What it is CMLA use
- Base Bottom support; often houses the lamp Stable platform; do not slide a wet scope
Light source Lamp in the base (or a mirror on old teaching scopes) Adjust brightness; do not crank to maximum as a focusing trick
Diaphragm Iris that sets the diameter of the light cone Open or close for contrast; wide open washes detail
Condenser Lens under the stage that focuses light on the specimen Raise for high-power work; center it; do not remove it because “it looks brighter”
Stage Platform with clips or a mechanical holder Move the slide with the stage knobs, not your fingers on a wet coverslip
- Objectives Lenses on the nosepiece (commonly 10×, 40×, 100×) Click each into place; start on low power
- Lens Any glass element (objective, ocular, condenser) Touch only with lens paper
- Ocular Eyepiece, usually 10× (binocular scopes have two) If you wear glasses, use the eye cups as trained
- Magnification How many times larger the image is Product of ocular and objective
Coarse adjustment Large knob; large focus travel Use on 10× to find the plane; never coarse-focus on 40× or 100× into the slide
- Fine adjustment Small knob; tiny focus travel Use on 40× and 100×
- Immersion oil Oil that matches glass refractive index at 100× 100× only ; oil on 40× ruins the high-dry lens
AMT’s outline spells “fine/course.” The knob is coarse (large movements), not “course work.” Exam stems may use either spelling; the function does not change.
Total magnification = ocular × objective. 10× ocular × 10× objective = 100× . 10× × 40× = 400× . 10× × 100× = 1000× . You do not add the numbers (10 + 40 is not 50×), and you do not oil a 40× lens “to get 1000.”
Light path
Light is born in the base , shaped by the diaphragm , focused by the condenser onto the specimen on the stage , collected by the objective , and magnified again by the ocular . If the field is dark, check the lamp, the diaphragm, the condenser height, and whether an objective is clicked in—before you twist coarse adjustment through the slide.
Prepare a urine sediment slide (assistant scope)
Follow the laboratory SOP. Classic manual teaching (volumes and g-force are SOP numbers, not improvisation):
Mix the specimen. Pour a measured volume (often about 12 mL) into a labeled centrifuge tube.
Centrifuge at the SOP relative centrifugal force and time (classic teaching is about 400–450 × g for 5 minutes). Too hard packs casts into a button you then dump; too light leaves cells in the supernatant.
Decant or pipette off supernatant, leaving a uniform small residual volume. Do not drain dry and then “add a drop of water to save it.”
Gently resuspend the button. Place one drop on a labeled slide and add a coverslip for a wet preparation . Avoid bubbles (artifacts).
Optional supravital stains (for example Sternheimer-Malbin) only if the SOP uses them. Do not invent a Gram stain on a UA cup and call it C&S.
Examine sooner rather than later . Casts dissolve in alkaline dilute urine; trichomonas motility fades; bacteria multiply in delayed unpreserved sediment.
What you look at, at which power:
10× objective (100× total): scan the entire coverslip for casts , large crystals, mucus, and to find a representative area. Casts are easy to miss if you jump straight to 40× in one corner.
40× objective (400× total): identify and count cells , bacteria, yeast, crystals, trichomonas, and spermatozoa. This is high-dry . No oil.
100× oil: not the routine UA counting objective. Oil is for stained smears (Gram stain is Chapter 13), not for a wet coverslip you still need to scan on 40×.
Brightfield is the default teaching method. Some laboratories use phase contrast for hyaline casts. Use what the SOP validates. Report using the laboratory’s format (cells per high-power field, casts per low-power field). Do not upgrade a wet drop into a species-level microbiology identification.
PPM is not a CMLA sign-out category
Provider-performed microscopy is moderate-complexity testing that CLIA allows certain licensed providers to perform under a PPM certificate (42 CFR 493.19). AMT IV.11.A.6 states the same restriction: PPM is providers only . The federal PPM procedure list includes:
- Direct wet mounts (bacteria, fungi, parasites, cellular elements)
- KOH preparations
- Pinworm examinations
- Fern tests
- Post-coital mucus examinations
- Urine sediment examinations when performed as PPM
- Nasal smears for granulocytes
- Fecal leukocyte examinations
- Limited qualitative semen analysis (presence or absence of sperm and motility)
A CMLA does not independently perform or sign out PPM procedures because “I can use a microscope.” Wet mounts, KOH, fern, and pinworm are the favorite exam names.
Separate idea: a laboratory with a Certificate of Compliance or Accreditation may assign manual urine microscopy to testing personnel who are trained, competency-assessed, and listed in the SOP. That is still not a personal PPM license. If you are in a Certificate of Waiver site, manual sediment microscopy is not a waived dipstick. Do not turn a closet microscope into an uncertified moderate-complexity department.
You may prepare the slide for a provider or a qualified analyst. Preparing is not signing the report.
General cleaning
Switch to 10×, lower the stage, remove the slide.
Oil: wipe 100× with lens paper immediately after use. Do not leave oil overnight. Never drag the 40× objective through leftover oil when you spin the nosepiece.
Optics: lens paper (or manufacturer wipes). Facial tissue and paper towels scratch coatings. A tiny amount of manufacturer-approved lens cleaner if SOP allows—not alcohol dumped on the ocular, not a xylene bath you invented.
Stage and base: disinfectant compatible with the instrument after a urine splash. Do not soak the electrical housing.
Cover the microscope. Carry it with two hands (base and arm), never by the oculars.
Do not use coarse adjustment as a bottle opener. Document lamp failures and damaged objectives instead of “making do.”
In practice
A waived clinic wants you to “just KOH that discharge and fern that mucus” because the microscope is already on. Those are PPM procedures. You do not independently examine or sign them, and you route the request to a provider credentialed for PPM or to the main laboratory. For a hospital UA with micro that your competency list includes, you spin the measured aliquot, coverslip a wet drop, scan on 10× for casts, identify on 40×, never oil the 40×, and clean the 100× only if you actually used it for a stained smear elsewhere.
- Exam traps
- Adding 10 + 40 = 50×, or oiling 40× to “get 100×.”
Coarse-focusing on high power through the slide.
Calling wet mount, KOH, fern, or pinworm CMLA-independent work.
Reporting unspun urine as a complete microscopic.
Cleaning optics with gauze, or leaving oil on the 100× so the 40× wades through it tomorrow.
Name the part, multiply the lenses, keep oil on 100×, and keep PPM on the provider’s side of the line.