A subungual haematoma (pronounced sub-UNG-gwal HEE-mah-toe-ma) is a bit like a blood blister. It results when there is bleeding under the nail. This blood causes a painful build up of pressure. It is also a sign that tissues under the nail have been torn or broken.
This photo shows a finger with a subungual haematoma – see the discolouration under the nail and the swelling of the finger? Compared to the normal finger, the injured finger has a convex surface to the nail. This patient had a crush injury to the finger that broke the bone under the nail (the "distal phalanx"). When the bone broke the nail bed also tore, causing bleeding under the nail. The nail stayed in place.
The broken bone didn’t require an operation, because the fragments of the bone were in a satisfactory position. The tear in the nail bed didn’t require an operation, because the nail held the nail bed edges together satisfactorily.
We did fix the subungual haematoma, draining the blood out from under the nail. We do this because the pressure caused by the build up of blood can be very painful and it may cause problems with future nail growth. Plus, it is easier for our hand therapist to make a protective plastic finger splint if the finger is not unduly swollen. In such instances the broken bone will need to be protected against further injury for 6 weeks, either with a plastic splint (a bit like a long thimble) or a bulky bandage.
If your finger looks like this please seek medical treatment.
Why is it called "subungual haematoma"?
Sub = under
Ungual = pertaining to the nail
Haematoma = collection of blood
Draining a Subungual Haematoma
Video warning: the following video contains footage of a subungual haematoma being drained. I do not recommend self-treatment and this procedure should be performed under sterile conditions to reduce the risk of infection. Keeping those caveats in mind, if you are not squeamish about blood you may find this interesting viewing: