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Trucut needle biopsy

From Mediwikis

A guide to the Trucut Needle Biopsy procedure by Michael Edwards FRCS. None of the information in this masterscript should be used without the agreement of a trained practising surgeon.



Contents

Aim

The user of the Trucut needle aims to provides the pathologist with a core of undamaged tissue from the lesion.

There should be sufficient tissue for the pathologist to make an accurate histological diagnosis based on the architecture as well as the cells in the specimen.

  • A fine needle aspirate will only provide cells.

The lesion is usually a swelling or thickened area.

It may be a suspicious area on an ultrasound scan.

The procedure is performed using a specially designed needle.

The use of a Trucut needle is described here.

Details of using alternative wide bore needles will be found in their packages.

Principle of Trucut biopsy (free needle technique)

Trucut image principle.png


The principle is very simple. A needle with a gap near its tip is passed into the lesion.

A surrounding sheath with a cutting tip is passed down the needle.

The sheath cuts a specimen corresponding to the gap in the needle.

The needle and sheath, with the specimen, are then removed from the patient.

Method

The success rate of Trucut biopsy is very user dependent.

The surgeon needs to perform several essential moves in addition to understanding the principle.

However, with a correct technique and attention to detail, the clinician can provide satisfactory tissue samples easily and consistently.

Case Selection

Trucut needle biopsy is often the second step in making a pathological diagnosis if, for instance, a fine needle aspiration is inconclusive.

It is preferable to fine needle aspiration if:

  • The pathologist wishes to obtain extra information. Eg Tissue typing of lymphomas.
  • The pathologist may not have sufficient experience with eg Thyroid swellings.
  • The lesion sampled may not be suitable. Eg Inflammatory v neoplastic lymph nodes.

A few minutes discussing the case with your pathologist will clarify the best method of making a diagnosis.

Unsuitable patients

  • Very nervous.
  • Low pain threshold.
  • Previous bad experience of needle biopsies.
  • Child.
  • Anticoagulated.
  • Bleeding disorder.
  • Dangerous site EG Near eye, major blood vessels or nerves.
  • Tender site EG Nose, Perianal, Perineal, Penis, Female genitalia, Digits
  • Unsuitable lesion
  • Tender tissue. Eg Tender breast fibroadenosis

Equipment, materials and spares  list

  • 1 x  equipment, materials and spares list
  • 1 x instrument tray
  • 1 x sterile disposable gloves to fit
  • 1 x trucut biopsy needle
  • 1 x propanol skin swab (eg mediswab)
  • 1 x  5 ml syringe
  • 1 x orange 25 swg 0.5mm. Diameter needle
  • 1 x 5ml. Plain 2% lignocaine
  • 1 x disposable no 11 scalpel with a straight blade
  • 1 x packet of 5 gauze swabs
  • 1 x skin plaster (eg elastoplast spot dressing)
  • 1 x packet of steristrips
  • 1 x suture pack with suture eg vicryl ethicon w9890
  • 1 x formaldehyde fixative specimen pot  ( from pathology laboratory).
  • 1 x histology form
  • 1 x waste bin
  • 1 x sharps bin
  • 1 x examination couch which can be tilted head down in case of fainting (trendelenburg manoeuvre)

Skills to Learn

There are several skills which the trainee needs to master before performing a Trucut biopsy on a patient.

Finding and fixing the lesion with the non-dominant hand

This is likely to be most unfamiliar.
Start by finding the lesion using the digits of both hands.
Make sure that you can feel the area of interest.
Localise and fix the area of interest with the digits of your non-dominant hand (left hand in this script).
Practice this on 20 patients with, for instance, breast swellings.

Handling the Trucut Needle

The Grip

When pushing the needle and sheath through the skin:
First check that the distal end of the sheath lies in line with the point of the needle.
The sheath will give a click as it reaches position.
The hand grip of the sheath will now be at a maximum distance from the hand grip of the needle.
Place your dominant hand firmly over both hand grips so that the sheath cannot move on the needle.

Bracing

Trucut biopsy requires a strong force of 1000gm or more to pass through the tissues.
At the same time:
The needle and sheath have to be manipulated one against the other in a smooth, controlled fashion.
The patient has to be protected from sudden uncontrolled lurches of the instrument.
This requires very controlled strong bracing of the surgeon’s body.
ie A strong stance with the feet shoulder-width apart.
Knees slightly flexed.
Body slightly crouched.
Elbows held closely to the sides of the body.
Wrists firm.

The Moves

The Starter Grip
This grip is used when pushing the needle through the skin and subcutaneous tissues to the lesion.
The sheath needs to cover the needle end completely.
The hand grips of the needle and sheath will be at maximum separation.
Grasp the handle of the instrument firmly with your right hand so that the needle and sheath hand grips stay apart.
Brace yourself.
Grip Change
Without moving the handle of the instrument:
Hold the sheath hand grip with your left hand.
Move your right hand so that it holds the needle hand grip only.
Push the Needle out
Use your right hand.
Prevent the sheath moving by bracing yourself and holding the sheath grip firmly with your left hand.
Push the needle out until the needle hand grip hits the hand grip of the sheath.
Slide the Sheath down the needle
Use your right hand.
Feel the sheath sliding.
Make the movement smoothly..
The end point is a click, heard and felt when the sheath reaches the very end of the needle.
At this point, the needle and sheath hand grips are apart.
Repeat 10 times.
Slide the sheath down with 3 or 4 small, controlled jerks.
This will simulate cutting through a tough lesion.
Repeat 10 times
Withdraw needle and sheath
Hold the hand grips of needle and sheath firmly in your right hand.
Pull the instrument away to the right.
It is helpful to chant the sequence as you are doing the procedure.
Chant it to yourself when performing the procedure on a patient.
ie PUSH – SLIDE - WITHDRAW

Preliminaries of Procedure

Checking equipment, materials and spares

Check against the equipment and materials list.

Assembling Equipment and Spares

Check the Trucut Biopsy

Check the sheath will completely cover the needle

Check Local Anaesthesia

Check the agent, strength and expiry date.

Check Scalpel

Check the correct blade is present.
Eg Swann-Morton no 11 .
For a non-disposable scalpel:
Check the blade is correctly attached.

Check Fixative

Check the fixative is formaldehyde.
Check that the fixative is at least 5cm. deep to allow the specimen to be shaken off the needle later.

Check the Patient

  • Check you have discussed the case with the pathologist
  • Check you have the correct patient
  • Check you have the correct side
  • Check the consent form
  • Check the lesion is still palpable
  • Check the patient has not found another lesion
  • Check the patient is not anticoagulated or has a bleeding disorder
  • Check there is no other procedure to do

BIOPSY PROCEDURE

Position the patient

Remove enough of the patient’s clothing so that there is no risk of blood staining.
Position the patient so that the lesion is accessible.
For breast, thyroid and most lymph node lesions:
Supine (Ed face up).
Ideally, position the patient horizontal, to minimise the effects of a faint.

Stance

Stand on the side of the patient that is most familiar to you and in reach of the lesion.
This will usually be on the patient’s right hand side.

Explain each clinical step before you do it

Swab the skin

Use a propanol swab (eg a Mediswab).
Sterilise a 10 cm. diameter area centred on the site of clinical interest.
Do not inject local anaesthesia into the lesion, because it will disappear into the infiltrated tissue.
EMLA cream can be used to reduce surface pricking sensation.

Fix the lesion

Use the fingers of your left hand to surround the lesion.
Do not touch the skin over the centre of the lesion.

Choose the needling point

This will usually be in the centre of the site of the lesion.

Warn the patient

Tell the patient that there will be a slight sting as the anaesthetic needle goes into the skin.
Be prepared for the patient to jump or make a sudden movement as the needle is inserted.

Inject the local anaesthetic

Raise a bleb of local anaesthetic in the skin.

Incise the skin

Use the no 11 scalpel.
Make a 6mm. incision through the skin.
This will allow a 4mm. needle and sheath to pass through the skin.
(Length of incision is Π times the diameter of the round bodied needle and sheath.)

Grasp the trucut hand grips

Use your right hand.

Brace yourself

Push the needle and sheath into the skin

Push the needle through the skin and subcutaneous fat to the edge of the lesion.

Change your grip

Hold the sheath hand grip in your left hand and the needle hand grip in your right.
Make sure the needle and sheath do not lose their place at the edge of the lesion.

Hold the sheath and the grip motionless

Using your left hand.

Push the needle into the lesion

If the lesion is a carcinoma:
The tissue grates slightly, like an unripe pear.
If the lesion is benign:
The tissue (eg Breast fibroadenosis) feels more rubbery.
If the needling is too painful:
Stop the procedure.
Consider doing a Trucut or drill biopsy under sedation at a later date.
If the lesion is tougher:
Push with a more jerky action.
Push with up to 1500gm. of force.

If the lesion is so tough that more than this amount of force is needed:

Bent needle.png

The needle may bend.
If the needle bends:
Pull the needle out.
This is painful for the patient.
Repeat the procedure using the Sheathed Needle Technique.

Sheathed needle.png

If needle cannot be pulled out:
Consider giving sedation or even a general anaesthetic
Do not try to push the sheath over the bent needle tip.
This may break the needle.
If you feel the lesion is too tough for the Free Needle technique from the outset:
Consider the Sheathed Needle Technique.
Consider a drill biopsy or open biopsy.
FOR EITHER THE FREE OR SHEATHED NEEDLE TECHNIQUE:
Make sure you hear and feel the click as the sheath reaches the end of the needle.
If there is no click:
The sheath may not cut the specimen completely.

Incomplete cutting.png

On withdrawing the needle and sheath, the specimen will remain in the lesion.
If there is no specimen:
Repeat the needling using a proper click.

Place a gauze swab on the wound

Inspect the specimen

Slide the sheath off the needle
If there is a specimen at least half the length of the gap in the needle:
Place the end of the needle and the specimen in the formaldehyde bottle.
Shake the needle end in the formaldehyde solution to free the specimen.
Do not use forceps to pick up the specimen.
This may crush the specimen and make the assessment difficult for the pathologist. (Crush artefact).
If the specimen sinks in the fixative:
It is likely to be tumour or other pathological breast tissue.
Send the specimen for histological examination.
If the specimen floats:
It is likely to be fat.
Obtain another specimen.
If the specimen that half floats and half dangles downwards:
It is likely to be part fat and part pathological tissue.
Send the specimen to the laboratory, but also obtain another specimen.

Final Touches

Check all sharps are in the sharps bin

Check all swabs

Label the fixative bottle

Write the patient’s name, hospital number, date of birth, date of aspiration and site of aspiration.

Fill in the histology request form

Write the patient’s name, hospital number, date of birth, date of aspiration, site of biopsy, referring consultant, address, referring hospital/clinic.

Write to the patient’s general practitioner and referring physician

Check the patient’s wound

Check that there is no bleeding.
Continue pressure with a swab for 3 minutes until the bleeding stops.
If the bleeding continues:
Close the needle site with a Steristrip.
If this does not work:
Insert a stitch.

Check there is no further procedure to perform

Thank the patient

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