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Epic Code LAB2111047 Electron Microscopy, Varies

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Useful For

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

Specimen Type


Ordering Guidance

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


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


For muscle specimens, see MBX / Muscle Pathology Consultation.


For CADASIL (cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy) genetic testing on blood, call 800-533-1710 for options.


For cardiac biopsy disorders, see 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

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.

Specimen Minimum Volume

See Specimen Required

Specimen Stability Information

Specimen Type Temperature Time Special Container
EM Ambient (preferred)

Reject Due To

Muscle tissue
Fat pads
Hair shaft
Liver/gastrointestinal tissue


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 Information

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.

Method Name

Electron Microscopy

Report Available

5 to 10 days

Reporting Name

Electron Microscopy

Reference Values

An interpretive report will be provided.


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.

Method Description

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)

Day(s) Performed

Monday through Friday

Clinical Reference

Schroder JA: Diagnostic transmission electron microscopy. Imaging and Microscopy. 2012. Accessed January 20, 2022. Available at

Test Classification

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


LOINC Code Information

Test ID Test Order Name Order LOINC Value
EM Electron Microscopy 34166-9


Result ID Test Result Name Result LOINC Value
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