Specimen collection and fixation – Histology
Specimens for histology analysis must be placed in 10% formal saline fixative (known as ‘fixed’) at room temperature.
All sample containers must be clearly labelled with a minimum of 3 patient identifiers (Patient first name, surname, date of birth and/or hospital number) and state the type of sample on the label.
If more than one specimen from the same patient attributed to a case is sent they should be clearly indicated as part 1, 2, 3 etc with a note on the request form as to what each part is and where it has come from anatomically e.g. 1. Gastric, 2. Duodenal or 1. Skin from upper back, 2. Skin from leg.
Samples sent over as ‘fixed’ specimens must be in a suitable sized, leakproof sterile container with a suitable volume of fixative, so that the whole sample is immersed, sent to the laboratory as soon as possible. Ideally there should be at least 3 times the volume of fixative in ratio to the size of the sample to ensure adequate fixation.
All samples from known or potential carriers of Hazard Category 3 pathogen (TB, Hepatitis B, Hepatitis C or HIV) MUST be clearly labelled with ‘HIGH RISK’ stickers on both the request form and the sample container and sealed in a separate specimen bag. If there is any doubt as to whether a specimen is high risk, please contact laboratory.
The sample types listed below have specialised collection requirements:
Frozen sections
These should be pre-booked with the laboratory at least 3 working days in advance and should be immediately transported directly to the laboratory as fresh and unfixed tissue in a sterile container. They MUST NOT be left at the pathology reception area.
Urgent requests for frozen section MUST always be discussed with a Consultant Pathologist. Otherwise a telephone call or email to the laboratory requesting a frozen section will be accepted provided the letter states;
– Date of Biopsy and time
– Specimen type
– Clinical suspicion
– Consultant in charge
– Ward/Area frozen section will take place and extension number,
Please note that samples with known Hazard Category 3 infections e.g. High TB risk, known HIV, Hepatitis B or C sent for frozen sectioning will not be accepted or processed. Samples of this high-risk nature will be placed in a formalin fixative and processed as a routine Histology sample. If such a sample is inadvertently processed, full decontamination of the equipment used will be required, and during this time no further frozen sections can be performed for at least 24hrs. Such instances will be recorded as clinical incidents.
The frozen section should arrive with:
– Accompanying Histology request form with details to allow patient identification
– Clinical Details
– Extension Number for result
– Consultant in charge
The result of the frozen section is telephoned by the consultant pathologist to the consultant in charge.
Immunofluorescence (IMF) studies
These should be sent to the laboratory in a special transportation fluid called ‘Michel’s medium’, which can be obtained from the laboratory. These samples are sent to an external referral laboratory for testing.
Muscle biopsies
These are to be sent fresh and unfixed in a sterile container and pre-booking is required with the laboratory in advance as these sample are sent to an external referral laboratory for testing.
Skin biopsies for Intra-Epidermal Nerve Fibre Density (IENFD)
this requires a specialist fixative kit and must be pre-ordered with the laboratory at least 5 working days in advance. Pre-booking is required with the laboratory in advance as these sample are sent to an external referral laboratory for testing.
Testicular biopsies
These should be placed in a special pre-fixative called ‘Bouin’s fluid’ available from the laboratory on request.
Formalin-fixed tissue is unsuitable for Microbiology bacteriological examination. If this is required then please send two separate pots with two separate request forms, one with fresh tissue in a sterile container and an accompanying Microbiology request form and one formalin fixed tissue sample with an accompanying Histopathology request form.
Buffered formal saline, Gynae and Non-Gynae PreservCyt vials and small pre-filled specimen pots are available from the department on request. Large specimen buckets and 30ml universal containers are available from our stores department and must be ordered directly from them.
To ensure the prepared microscopic slides are available for our pathologists to report on the next day, fixed specimens need to be received before 4:30pm and labelled as urgent, if clinically required, for next day reporting.
If samples are very urgent and for same-day processing, we will need to receive these samples by 10am. (This is not recommended for samples that may require further molecular testing). To arrange this service please contact the department directly and in advance of sending the sample.
Larger specimens or bone samples requiring decalcification or further fixation may require a longer reporting time period. Samples requiring specialised molecular tests may require a longer reporting time period.
