Specimen requirements – Paediatric Histopathology

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All specimens should be sent to the laboratory in an appropriately labelled specimen pot that is large enough to easily accommodate the specimen. It is unsafe practice to label specimen pots in advance of a procedure.

Factors affecting performance

The following is a list of factors known to significantly affect the performance of examination and interpretation of results:

  • Failure to follow the specimen acceptance policy will result in a delay to specimen processing and reporting.
  • Failure to supply adequate clinical information may result in a delay to requesting of specimen investigations and reporting.
  • Failure to label requests as urgent or HSC205 will result in a delay to specimen processing and reporting.
  • Failure to fix specimens appropriately and in a timely manner will adversely affect specimen integrity and subsequent histological examination.
  • Failure to follow instructions for the specific specimen requirements will prevent necessary examinations from being performed.
  • Failure to disclose high risk status of the specimen will put staff at unnecessary risk of infection.
  • Specimens for frozen section placed in 10% neutral buffered Formalin will result in a frozen section not being performed and therefore a rapid report would not be possible.
  • Failure to contact consultant/laboratory in advance for a frozen section may result in a delay or even a scenario where it cannot be performed, due to a lack of availability of technical staff and/or Consultant staff.
  • Specimens for immunofluorescence placed in 10% neutral buffered Formalin will prevent necessary immunofluorescence examinations.
  • Muscle biopsies for enzyme histochemistry must be transported immediately to maintain enzyme and protein membrane integrity, failure to do so will result in poor/low diagnostic yield.
  • Muscle biopsies placed in 10% neutral buffered formalin will prevent any necessary enzyme histochemistry testing.
  • Rectal biopsies placed in 10% neutral buffered formalin will prevent any necessary enzyme histochemistry testing.

Specimen fixation

Specimens for routine histology are required to be placed into 10% neutral buffered formalin, which is available on request from the laboratory. Formalin is used to fix the specimen and preserve the tissue in as life-like state as possible. If there is a delay between the removal of the tissue and fixation in formalin, this can adversely impact the specimen integrity and therefore report.

To ensure proper specimen fixation, the following guidelines should be adhered to:

  • Specimen container – should be appropriately sized and large enough to easily accommodate the specimen
  • Formalin – ensure adequate volumes of formalin are used
    • 1:5 tissue to formalin ratio for very large specimens
    • 1:10 tissue to formalin ratio for small specimens where possible
    • Ensure the details on the specimen pot and request card match, are legible and a formalin hazard label is attached
  • Ensure the lid of the specimen container is securely fastened
  • Use a plastic biohazard sealable specimen bag (where possible) for the specimen pot and place the request card in the pocket

All specimens in formalin should be stored at room temperature and not in the fridge prior to transport to the laboratory.

High risk specimens

Specimens that potentially contain category 3 pathogens (for example, SARS-coV-2, mycobacterium, HIV, hepatitis B or hepatitis C) must be clearly labelled as HIGH RISK on both the request card and on the specimen pot to ensure the health and safety of all staff. Please refer to the Advisory Committee on Dangerous Pathogens (ACDP) website for a comprehensive list of Category 3 human pathogens.

The date and time that the specimen is taken should be recorded on the request card for all high risk specimens to enable the laboratory to calculate the fixation time on receipt. This information will minimise the infection risk to staff and prevent undue delay to processing. All high risk specimens are to be fully fixed before being processed by the laboratory.

Frozen sections, muscle biopsies and immunofluorescence investigations will not be performed on any high risk or potentially high risk specimen.

Frozen sections

All intra-operative frozen sections should be booked with the laboratory by contacting the laboratory on 0161 701 2240 to ensure the availability of the appropriate scientific and consultant staff. Every attempt will be made to provide frozen sections during the laboratory opening hours, providing appropriate clinical and technical staff are available.

Frozen sections should be booked 24 hours in advance after discussion with a Consultant Pathologist. If this is not possible, for example in an emergency, a Consultant Pathologist should be contacted as soon as possible. When booking a frozen section, please provide the following information;

  • Patient information
  • High risk status
  • Clinical information
  • Clinician name
  • Theatre number
  • Contact number

The specimen for frozen section should be transported to the laboratory in an appropriately labelled dry specimen container and must arrive by 5.00pm. Formalin must not be added. Specimens should be handed directly to the technical staff at histopathology specimen reception as a matter of urgency to ensure a timely report is issued.

Frozen sections will not be performed on any high risk or potentially high risk specimen.

When the specimen is ready to be sent to the laboratory, or if there is a delay in theatre, please contact the laboratory. If a frozen section is no longer required, please contact the laboratory immediately to cancel.

Urgent specimens

If a specimen requires an urgent report, the laboratory should be contacted on 0161 701 2240 to request this. However, it is important to state that specimens for histological analysis do need at least 24 hours fixation and a further 24 hours preparation time.  It is sometimes unwise to shorten this time, as it puts the quality of the specimen at risk.   Please liaise with us and we can advise you on the optimum way to deal with the sample, bearing in mind both the need for a rapid result and the requirement for good histology to make an accurate diagnosis.

Special specimens

In order to gain the maximum amount of information we need to treat certain specimens in a specific way.  In order to do this you need to liaise with us before you take the specimen, to discuss appropriate fixation, if any and transport.

The following specimens should be sent FRESH immediately following surgical removal and should be discussed with us in advance by telephoning the laboratory on 0161 701 2240 (fresh specimens should be refrigerated whilst awaiting porter/transport to the laboratory):

  • Tumours
  • Lymph node specimens suspicious of tumour
  • Skin biopsies for electron microscopy.
  • Skin biopsies for fibroblast culture are not for histopathology, and should be sent to either the Willink Laboratory or Cytogenetics.
  • Lung biopsies
  • Liver biopsies for metabolic disease (usually glycogen storage disease)
  • Cytology specimens
  • Renal Biopsies (see section 5.7)
  • Rectal Biopsies ( see Section 5.8)
  • Muscle Biopsies (see section 5.9)
  • Fresh Pancreatic Lesions – Congenital hyperinsulinism (see section 5.10)
  • Skin Biopsies for immunofluorescence (see section 5.11)
  • Bone biopsies for metabolic investigations (see section 5.12)

If you are unsure about anything, including whether a specimen should be sent fresh or fixed in formalin, please discuss this with us by ringing either a consultant histopathologist or a senior member of the technical staff (techniques requiring fresh specimens will not be available once the specimen is fixed)

Any other specimens should be fixed in formalin as soon as possible before transport to the laboratory. Formalin fixed specimens should be kept at room temperature.

Turnaround of specimens is at least 2-3 days for routine formalin fixed specimens. If extra specialist work is required the turnaround time will be increased. Specimens containing bone or teeth require decalcification and this can take days to weeks depending on the size of bone.

Factors that can significantly affect the interpretation of the sample results include poor fixation, drying artefact of unfixed specimens and cauterisation that occur from sampling artefact.

 

(Last reviewed May 2023)