Test Catalog

Test Id : EM

Electron Microscopy, Varies

Useful For
Suggests clinical disorders or settings where the test may be helpful

Providing information to aid in the diagnosis of medical disorders such as storage diseases, CADASIL (cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy), and primary ciliary dyskinesia


For more information see Primary Ciliary Dyskinesia.

Special Instructions
Library of PDFs including pertinent information and forms related to the test

Method Name
A short description of the method used to perform the test

Electron Microscopy

NY State Available
Indicates the status of NY State approval and if the test is orderable for NY State clients.


Reporting Name
Lists a shorter or abbreviated version of the Published Name for a test

Electron Microscopy

Lists additional common names for a test, as an aid in searching

Electron Microscopy (Tissue)

Electron Microscopy, Not Renal

EM (Electron Microscopy-Tissue)

Immotile Cilia Syndrome


Primary Ciliary Dyskinesia (PCD)

CADASIL Tissue Only

Electron Microscopy WBC

NCL (Neuronal Ceroid Lipofuscinosis)

Cerebral Autosomal Dominant Arteriopathy with Subcortical Infarcts and Leukoencepholopathy

Specimen Type
Describes the specimen type validated for testing


Ordering Guidance

For nontumorous renal specimens, order RPCWT / Renal Pathology Consultation, Wet Tissue.


For platelet disorders, order PTEM / Platelet Transmission Electron Microscopic Study, Whole Blood.


For muscle specimens, order MBX / Muscle Pathology Consultation.


For CADASIL (cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy) genetic testing, order NTC3Z / NOTCH3 Gene, Full Gene Analysis, Varies.


For cardiac biopsy disorders, order ANPAT / Anatomic Pathology Consultation, Wet Tissue.


For neuronal ceroid lipofuscinosis (NCL) testing, see TPPTL / Tripeptidyl Peptidase 1 and Palmitoyl-Protein Thioesterase 1, Leukocytes or NCLGP / Neuronal Ceroid Lipofuscinosis (Batten Disease) Gene Panel, Varies

Shipping Instructions

Whole blood specimens must arrive within 48 hours of collection.


Necessary Information

Failure to supply the following documentation will result in a testing delay:

1. Completed Electron Microscopy Patient Information must be submitted with each specimen.

2. Tissue source required and reason for electron microscopy must be indicated for testing to be performed.

3. Tumor biopsies must be accompanied by a history, hematoxylin and eosin-stained slides and a paraffin block.

Specimen Required
Defines the optimal specimen required to perform the test and the preferred volume to complete testing

Specimen Type: Fixed wet tissue

Supplies: Electron Microscopy Kit (T660)

Container/Tube: Electron Microscopy Kit or leak-proof container

Specimen Volume: Entire specimen

Collection Instructions: Collect specimen according to the instructions in Electron Microscopy Procedures of Handling Specimens for Electron Microscopy. Do not place on ice, dry ice, or freeze.

Additional Information:

1. PATHC / Pathology Consultation may be added if deemed necessary by the reviewing pathologist.

2. Liver/gastrointestinal and hair shaft specimens are not acceptable. Testing will be canceled if one of these specimen types is received.


For neuronal ceroid lipofuscinosis (NCL) testing only

Specimen Type: Whole blood

Container/Tube: Green top (sodium heparin) or yellow top (ACD solution B)

Specimen Volume: 5 mL

Collection Instructions: Send whole blood specimen in original tube. Do not aliquot.

Additional Information: If test indication is for NCL, whole blood may be submitted in lieu of fixed wet tissue. This is only applicable for a presumptive diagnosis of NCL; whole blood specimens submitted for any other reason will be rejected.

Special Instructions
Library of PDFs including pertinent information and forms related to the test


Specimen Minimum Volume
Defines the amount of sample necessary to provide a clinically relevant result as determined by the Testing Laboratory

See Specimen Required

Reject Due To
Identifies specimen types and conditions that may cause the specimen to be rejected

Muscle tissue
Fat pads
Hair shaft
Liver/gastrointestinal tissue

Specimen Stability Information
Provides a description of the temperatures required to transport a specimen to the performing laboratory, alternate acceptable temperatures are also included

Specimen Type Temperature Time Special Container
EM Ambient (preferred)

Useful For
Suggests clinical disorders or settings where the test may be helpful

Providing information to aid in the diagnosis of medical disorders such as storage diseases, CADASIL (cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy), and primary ciliary dyskinesia

Clinical Information
Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

Transmission electron microscopy is an important diagnostic tool used in the comprehensive assessment of human disease and is most often used in conjunction with other methods such as light microscopy and immunohistopathological techniques. This fundamental technology can provide both confirmatory and diagnostic value to the pathologist and clinician.

Reference Values
Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.

An interpretive report will be provided.

Provides information to assist in interpretation of the test results

The images and case histories are correlated and interpreted by a pathologist who is an expert in the field of the suspected diagnoses.


Results will be provided by telephone. If requested, representative images showing diagnostic features will be sent.

Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

Certain factors are necessary for interpretation of electron microscopic images as follows:

-Optimal fixation of viable and representative tissue is imperative.

-The tissue submitted must have been viable at the time of fixation.

-Selection of tissue representative of the lesion is essential.

Clinical Reference
Recommendations for in-depth reading of a clinical nature

Schroder JA: Diagnostic transmission electron microscopy. Imaging and Microscopy. 2012. Accessed October 14, 2022. Available at www.imaging-git.com/science/electron-and-ion-microscopy/diagnostic-transmission-electron-microscopy

Special Instructions
Library of PDFs including pertinent information and forms related to the test

Method Description
Describes how the test is performed and provides a method-specific reference

The fixed tissues received are postfixed and stained in osmium tetroxide, dehydrated, and embedded in epoxy resin. Resin blocks are trimmed and semithin (1-micron) survey sections stained with toluidine blue are viewed using a light microscope. Blocks of interest are re-trimmed and the area for observation is then ultrathin sectioned, placed on copper mesh grids, and stained with lead citrate. The sections are examined with a transmission electron microscope operated at an appropriate kV. Images are digitally captured and stored electronically.(Winey M, Meehl JB, O'Toole ET, Giddings TH Jr: Conventional transmission electron microscopy. Mol Biol Cell. 2014 Feb;25(3):319-23. doi: 10.1091/mbc.E12-12-0863)

PDF Report
Indicates whether the report includes an additional document with charts, images or other enriched information


Day(s) Performed
Outlines the days the test is performed. This field reflects the day that the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time before the test is performed. Some tests are listed as continuously performed, which means that assays are performed multiple times during the day.

Monday through Friday

Report Available
The interval of time (receipt of sample at Mayo Clinic Laboratories to results available) taking into account standard setup days and weekends. The first day is the time that it typically takes for a result to be available. The last day is the time it might take, accounting for any necessary repeated testing.

5 to 10 days

Specimen Retention Time
Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded

Residual tissue: 2 months

Performing Laboratory Location
Indicates the location of the laboratory that performs the test


Several factors determine the fee charged to perform a test. Contact your U.S. or International Regional Manager for information about establishing a fee schedule or to learn more about resources to optimize test selection.

  • Authorized users can sign in to Test Prices for detailed fee information.
  • Clients without access to Test Prices can contact Customer Service 24 hours a day, seven days a week.
  • Prospective clients should contact their Regional Manager. For assistance, contact Customer Service.

Test Classification
Provides information regarding the medical device classification for laboratory test kits and reagents. Tests may be classified as cleared or approved by the US Food and Drug Administration (FDA) and used per manufacturer instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR) product.

This test has been cleared, approved, or is exempt by the US Food and Drug Administration and is used per manufacturer's instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.

CPT Code Information
Provides guidance in determining the appropriate Current Procedural Terminology (CPT) code(s) information for each test or profile. The listed CPT codes reflect Mayo Clinic Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.

CPT codes are provided by the performing laboratory.


LOINC® Information
Provides guidance in determining the Logical Observation Identifiers Names and Codes (LOINC) values for the order and results codes of this test. LOINC values are provided by the performing laboratory.

Test Id Test Order Name Order LOINC Value
EM Electron Microscopy 34166-9
Result Id Test Result Name Result LOINC Value
Applies only to results expressed in units of measure originally reported by the performing laboratory. These values do not apply to results that are converted to other units of measure.
71033 Interpretation 59465-5
71034 Participated in the Interpretation No LOINC Needed
71035 Report electronically signed by 19139-5
71037 Material Received 81178-6
71788 Case Number 80398-1

Test Setup Resources

Setup Files
Test setup information contains test file definition details to support order and result interfacing between Mayo Clinic Laboratories and your Laboratory Information System.

Excel | Pdf

Sample Reports
Normal and Abnormal sample reports are provided as references for report appearance.

Normal Reports | Abnormal Reports

SI Sample Reports
International System (SI) of Unit reports are provided for a limited number of tests. These reports are intended for international account use and are only available through MayoLINK accounts that have been defined to receive them.

SI Normal Reports | SI Abnormal Reports

Test Update Resources

Change Type Effective Date
Test Changes - Specimen Information 2021-07-14