Nail Trephination

Bleeding under the nail from blunt trauma can be very painful. Lucky we have the tools on hand to ease some of that pain.

Bleeding from the vascular nail bed results in increased pressure, the creation of a hole (or window) through the nail allows for the bleeding, release of pressure and reduced pain.

This technique should be used only in the case of confirmed and simple trauma.

If there is significant trauma to the nail, nail bed or digit then,

you probably have better things to worry about,
trephining the nail is likely not going to be very effective.

The digit should be assessed as usual. Special care taken to rule out extensor tendon rupture.

X-ray to rule out distal phalanx fracture should be considered and is recommended in haematoma over 50% of the nail bed.

There is a belief that trephination shouldn’t be undertaken if there is an underlying fracture. There is good evidence that this is not the case, and there is no need to prescribe prophylactic antibiotic in this case.

There are a number of techniques available, the most common are use of a high temperature cautery or trephining pen, and use of a needle to”drill” the nail. However the recommended method is the use of a cautery pen or similar.

This is has a number of benefits

It is quicker, taking only a few seconds in most cases, especially useful in children and other anxious patients.
It should cause less pain. The downward force need to drill the nail increases the pressure on the nail bed and the patients pain.
You are less likely to cause further trauma to the nail bed (e.g. from the needle breaking through the nail and hitting the nail bed.
There is less chance of injury to the clinician. The needle slipping when initially performing the procedure is a real risk. And at the end you have a contaminated sharp to dispose of.

Of course there are some disadvantages too

They are expensive.
Not as widely available / need specially supplying in most situations.
Patients can complain of discomfort from the heat of the pen.
There is a risk of thermal injury to the nail bed if the pen tip does ‘break through’

Technique

Make a hole at the base of the nail or in the centre of the haematoma. This hole must be large enough for the haematoma to drain. Using a cautery pen, apply gentle pressure with repeated, quick motions until blood drainage is observed. Applying prolonged constant pressure with heat can result in pain and/or burns.

Once the nail has started to bleed, some gentle pressure to the base of the nail maybe of help in expressing the haematoma, dress the wound as appropriate and encourage the patient to allow the digit to hang down for a couple of hours to allow it to drain before the usual elevation. Usual wound care advice should be given, though warn the patient the nail may well come away.

PEARLS

Cautery pen is preferred method.
When appropriate, take an x-ray of the finger to rule out an underlying fracture that may require splinting.
No need to prophylactic antibiotic in associated simple distal phalanx fractures.
Always check for an associated extensor tendon injury.
The nail may fall off during the week following haematoma drainage but should regrow as long as the germinal matrix is intact.
Multiple holes may be necessary for adequate drainage.
Drainage of the subungual haematoma does not accelerate healing or prevent infection.
Use of paperclips or other objects heated with an open flame should not be practiced.

https://emedicine.medscape.com/article/82926

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