Leeds Children’s Hospital Paediatric Punch Skin Biopsy for Fibroblast Culture Standard Operating Procedure

• Allergies
• Background
• Procedure Method (Step by Step)

Allergies

Please check the patient’s allergy status, as they may be allergic to Chlorhexidine, and an alternative will be required.

Be aware: Chlorhexidine is considered an environmental allergen. Refer to the asepsis guidance.

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Background

Skin biopsy is used to culture fibroblasts in order to diagnose chromosomal abnormalities and metabolic disorders.  DNA may also be extracted if required.

A skin biopsy may be necessary for investigation of disease aetiology in a dying patient.

If required, a skin biopsy should be obtained within 24 hours post-mortem in cases of sudden unexpected neonatal death, or peri-mortem in the infant or older child. 

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Procedure Method (Step by Step)

1. Where possible, the procedure should be timed so that the sample reaches the laboratory between 09:00 and 16:00 Monday to Friday (excluding public holidays).

2. Telephone the Cytogenetics laboratory at least one working day before the procedure to request skin biopsy medium if possible. They may not be able to get this to you if less notice is given. When it arrives, it should be stored in the fridge until the procedure is to take place.

3. Informed consent should be obtained before undertaking a skin biopsy as an elective investigation in a living patient.

4. For post mortem skin biopsies, taken outwith an autopsy (licenced under LTHTs Post Mortem Human Tissue Act (HTA) licence), to take place in PICU, NICU and EDs only), consent should be documented in the patient notes, the local HTA Person Designated (PD) informed and the Notification form completed, as per the local HTA pathway (both documents with PD contact details are available on the relevant unit).

5. Complete genetics request available at Link  An R number for the testing is required. For this, add R322 - Skin fibroblasts to be cultured and stored, along with R346 - DNA to be stored. Other R numbers can be added later.

6. Perform Team Brief checklist with the whole team who will be present for the biopsy.

Collect equipment:
Specimen pot containing culture medium if possible or sterile 0.9% sodium chloride
Chlorhexidine skin prep (follow the Surgical Site Skin Preparation within the Perioperative Environment SOP section on children and neonates for recommended skin prepping methods). If patient is allergic to chlorhexidine, a gentle skin cleanser that does NOT include alcohol or iodine should be used. 0.9% sodium chloride may be used to prep visibly clean skin
Sterile drape
Sterile gauze
Steristrips
Biopsy punch 3-5mm dependent on patient age and tests required*
Scissors or scalpel
Dissecting forceps
Local anaesthetic
2ml syringe
Needle to draw up the local anaesthetic
Smaller needle to inject the local anaesthetic
Sterile dressing
Micropore 

*If the biopsy is being performed for a single test, a 3mm sample is fine. If multiple tests are planned or the child is unlikely to survive, consideration should be given to using a larger biopsy or taking two separate biopsies. Do not place more than one biopsy in a specimen pot. Use 2 separate pots if 2 biopsies required. If 2 pots of skin biopsy medium are not available, it is acceptable to place the second biopsy in 0.9% sodium chloride

7. Prepare skin biopsy specimen pot prefilled with medium. If the medium appears clear, not cloudy, it is appropriate to use; if not available use a universal specimen container with sterile 0.9% sodium chloride. Ensure pot is labelled with name, date of birth and NHS number

8. Call taxi (specimen collection service) stating time to collect specimen. Inform taxi to drop specimen off for cytogenetics testing at the specimen reception, Level 5, Bexley Wing, SJUH

9. Prior to starting the procedure conduct a sign in / time out checklist

10. If patient is likely to move, consider marking the site with ink in case local anaesthetic entry point is not obvious. The areas recommended to sample from are the inner aspect of the upper arm, the antero-lateral aspect of the upper thigh or from a specific lesion

11. Clean the skin for 30 seconds with a chlorhexidine based solution as per guidance. Aqueous Cetrimide 0.15% chlorhexidine 0.015% solution is the preferred skin prep however if not available Chloraprep sticks may be used followed by a skin wash with 0.9% sodium chloride to ensure any alcohol residue is removed. Alcohol and iodine should NOT be used as these adversely affect cell culture.

12. Inject local anaesthetic and wait until it has worked.

13. Stretch the skin at 90° to the tension lines around the biopsy site.

14. Place the disposable biopsy punch tool at a perpendicular angle to the skin surface, and then introduce it firmly onto the skin.

15. The punch biopsy device should be rotated back and forth to allow the cutting edge to carry the punch down through the tissue. Stop the pressure when it enters the subcutaneous fat and beware of underlying structures such as nerves or vessels. The skin biopsy should be full thickness. Be aware that the biopsy device is surprisingly sharp. It will cut through the skin very quickly and the pressure required to reach the subcutaneous fat is actually very little.

16. Try to keep the blood contamination of the specimen to a minimum.

17. Withdraw the punch biopsy device and apply pressure on the puncture site with sterile gauze to achieve haemostasis. Remove the specimen gently from the punch using a needle.

18. More commonly the skin biopsy remains in situ, gently lift it from the site using either a 21 gauge needle or by grasping gently with forceps deep to the specimen. Cut the specimen free from its base with scissors or a scalpel.

19. Place specimen in the skin biopsy medium pot or the universal pot with sterile 0.9% sodium chloride to cover the specimen. Keep it the correct way up and transfer it promptly to the laboratory. (If a biopsy has to be taken late outside working hours, it should be stored in tissue transport medium or sterile saline in an emergency, and kept in the fridge then sent to the lab as soon as possible on the next working day.)

20. Apply pressure to the site and close with Steristrips. Apply a sterile dressing over this. A roll of dressing gauze held down by Micropore gives a good pressure dressing on top of this if required.

21. Document procedure in the patient’s notes

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