Pathology tests database

Sample and container requirements

o Specimens from outside the department requiring EM should be sent in a small sample container (e.g. bijou or Eppendorf tube) containing at least 2ml of an EM fixative. o A glutaraldehyde-based fixative such as 2.5% glutaraldehyde in phosphate buffer is ideal but 10% buffered formalin is also acceptable if material is immersed for only a short period of time and preferably for less than two weeks. o Where material available is insufficient for EM, tissue can be extracted from wax blocks. The quality of these preparations is suboptimal however some useful information may be obtained. The material in the wax block should be fixed and processed in line with standard histological methods meeting internal quality control criteria.

Minimum volume required

The optimal size of diagnostic tissue requiring processing for electron microscopy is as follows: the largest dimension should be no greater than 5mm and the smallest dimension no less than 1mm. Any specimen with the smallest dimension less than 1mm may not survive tissue processing. In larger tissue samples individual pieces should be no larger than 3 mm cubed and should be completely submersed in fixative.

Special requirements

N/A

Patient preparation

N/A

Sample viability

N/A

Turnaround time

• Renal and cardiac turnaround times are up to 28 days, but this could extend up to 6 weeks as this is a specialist service. • Muscle and nerve biopsies 10 to 14 weeks

Reference range

N/A

Clinical guidance

The Electron microscopy unit provides a regional, national and international service for the examination and diagnosis of renal, cardiac, muscle, skin and occasionally tumour biopsies at the ultrastructural level of cells. Electron microscopy is performed routinely at magnifications between 1500 and 70,000 times to examine the ultrastructure of cells and their surroundings which are invisible at magnifications achievable by light microscopy. The EM service is supported by outsourcing when required to the specialist EM facility at Leicester Royal infirmary. This facility is fully accredited by United Kingdom Accreditation Service (UKAS) ISO 15189:2022, reference number 8608.

Notes

Participant in UK NEQAS CPT Transmission Electron Microscopy scheme