VOL: 100, ISSUE: 46, PAGE NO: 59
Marion Richardson, BD, CertEd, RGN, RNT, DipN, is senior lecturer and programme leader, emergency nursing, University of Hertfordshire
A subungual haematoma is a collection of blood beneath a finger or toe nail.
It is often caused by a crush injury (Purcell, 2003) such as shutting a finger in a door or other types of trauma. Heim et al (2000) note that these haematomas can also be caused by repetitive trauma in athletes such as runners and dancers.
Systemic pathologies and medications may also cause subungual haematoma. Goodman et al (2002) cite melanoma, pemphigus vulgaris (autoimmune disease of the skin), blood dyscrasias and anticoagulant therapy as possible causes. Ghetti et al (2003) describe haematomas occurring under several nails resulting from chemotherapy. Buttaravoli and Stair (2004) mention melanoma, Kaposi’s sarcoma, and other tumours as possible causes. They note that if these are the causes, the history of the haematoma will not be consistent with a simple subungual haematoma.
Whatever the cause, subungual haematoma can be extremely painful (Heim et al, 2000) and a brief look at the anatomy of the nail will explain why.
Why is a subungual haematoma so painful?
The nail is a modification of the epidermis (the outer layer of the skin). It provides a protective covering and is very useful as a simple tool, for example when picking up small objects (Marieb, 2003). It contains keratin, which gives it its strength.
Each nail is attached to the surrounding skin by the cuticle or eponychium (Lumley, 2002), and is partly covered on three sides by nail folds (Fig 1).
Nails grow from a nail root situated proximal to the cuticle just below the skin on the dorsum of the finger or toe (Fig 1). The nail extends towards the tip of the digit over the nail bed or nail matrix (Marieb, 2003).
The nail bed has a very good arterial blood supply, which gives the nail its pinkish colour (Heim et al, 2000). There is also a very good nerve supply to the area, which allows us to feel all sorts of sensations, especially in our fingertips.
Trauma to the nail damages the tiny blood vessels and the resultant bleeding that can occur under the fingernail puts pressure on the many nerve endings in the nail bed, causing considerable local pain.
The nail is firmly attached to the nail bed and the two apposing surfaces are ridged to strengthen this bond (Goodman et al, 2002). There is no subcutaneous fat in the nail bed to cushion any trauma and because it is so close to the underlying distal phalanx (the bones of the fingers and toes), concurrent trauma to the bone is not uncommon.
A subungual haematoma causes marked tenderness as blood accumulates under tension in the nail bed (Goodman et al, 2002). Patients often present in acute care settings with pain caused by these injuries.
Views differ as to how these haematomas should be treated. The most common treatment is to trephine, or make a hole, in the nail to release the blood, reduce the pressure, and thus relieve the pain (Fig 2).
Kukula and Fell (2003) suggest that haematomas only need to be drained if they cover 25 per cent or more of the nail. They suggest leaving them to resolve spontaneously if they are smaller than this.
A number of authors, including Wang and Johnson (2001), recommend that when the haematoma covers 50 per cent of the nail or more, the nail should be removed and the nail bed repaired.
Batrick et al (2003) reviewed 312 papers to see whether research demonstrated that this additional intervention improved cosmetic and functional results. They conclude that there are insufficient studies to support nail removal and nail-bed repair, and that treatment by trephining gives a good cosmetic and functional result in adults and children who have a subungual haematoma but no other significant fingertip injury.
Buttaravoli and Stair (2004) suggest that splinting a lacerated nail bed by its own nail may be superior to suturing. They recommend that if there are obvious lacerations with open haemorrhage or broken nails, a digital block should be performed and the nail should be lifted for inspection of the nail bed and repair of any lacerations. Nails that have become loose at a nail fold, whether at the sides or the root, should be resited (Purcell, 2003).
Meek and White (1998) found that only two per cent of patients treated with simple trephining had a ‘poor’ outcome with nail splitting, and that the occurrence of these poor outcomes could not be predicted. These authors suggest that treatment with simple trephining is effective even if the haematoma is large.
Management when the terminal phalanx is fractured
There is a debate as to whether trephining should be used when the underlying terminal phalanx is fractured. Purcell (2003) reminds us that fracture should be excluded, as trephining a nail over such an injury will technically turn the fracture from a closed to an open one. This increases the risk of infection tracking down to the bone and causing osteomyelitis.
There are a number of treatment options but perhaps the best advice is that given by Buttaravoli and Stair (2004). They suggest that trephining a nail with an underlying fracture should only be carried out when there is sufficient pain to justify it.
If trephining is used, the patient should understand the potential risk of developing osteomyelitis, as well as the need to keep the finger clean and dry.
Some authors recommend the use of prophylactic antibiotics, but there is little empirical evidence to support their use.
Avulsion (tearing) of the extensor tendon from the distal phalanx of the digit is another possible complication that must not be overlooked (Buttaravoli and Stair, 2004).
Time lapse from injury
Buttaravoli and Stair (2004) suggest that 24 hours after the injury the pain will have subsided anyway so trephining may not significantly improve discomfort, but will expose the patient to the risk of infection.
Purcell (2003) says there is no benefit in trephining once the blood has congealed, but that this can take up to a week and helpful results may be achieved during that time.
Consensus on treatment
The consensus of opinion would seem to be that as long as the nail and nail margins are intact and there is no other underlying trauma, simple trephining is the preferred method of relieving pain in a traumatic subungual haematoma where the patient is experiencing pain at rest.
Practitioners should only carry out treatments for subungual haematoma following local policies and guidelines.
Methods for trephining
The haematoma should be drained under aseptic conditions. It is important to ensure that universal precautions for blood and body fluid are adhered to, as the blood is under pressure and may spurt out (Buttaravoli and Stair, 2004). Anaesthesia of the digit should not be necessary.
A number of different methods can be used to make a hole in the nail. These include:
- Hot cautery;
- A fine-point scalpel blade;
- Surgical drill;
Whatever method is used, it is essential to ensure that the hole is large enough to allow free drainage of the haematoma; it may be necessary to move the trephining instrument from side to side. Failure to do this may mean that the haematoma clots and reseals.
A very simple method involves the use of a paper clip with its tip heated in a spirit-flame lamp until it is red hot. It is extremely effective when carried out by a skilled practitioner. The procedure can be carried out quickly except when the nail is very thick (Purcell, 2003).
Bache et al (1998) describe the method in detail, noting that the hot tip of the paper clip should be applied to the central point of the haematoma.
A specially designed electronically heated cautery tip can also be used.
Buttaravoli and Stair (2004) recommend that sufficient pressure needs to be applied to melt through the nail. Simply holding the instrument in place can heat up the nail and increase the pain without making a hole in it. Pressure should be maintained until the operator feels a ‘give’ as the instrument passes through the nail. Patients may find the smell of burning nail unpleasant.
Caution should be exercised when using hot cautery trephination on a patient wearing artificial acrylic nails as these are flammable (Buttaravoli and Stair, 2004).
A special battery-powered drill can be used to make a hole in the nail. Alternatively, a large-gauge (white) hypodermic needle can be twisted back and forth between the operator’s fingers. Pressure needs to be maintained until the nail ‘gives’.
Fine-point scalpel blade
A number 11 scalpel blade can be used to cut a hole in the nail. The scalpel makes a bigger hole and this probably improves drainage, but the procedure is slower and more painful (Purcell, 2003).
Laser treatment is not commonly used to trephine nails. This method should only be performed by practitioners skilled in using laser equipment.
An article by Kaya et al (2003) describes a technique for evacuating the haematoma using a very fine 29-gauge insulin needle inserted very close to the nail plate. This method was found to be fast and simple and patients tolerated it. It is recommended for small haematomas of the second, third, and fourth toenails where trephining is more difficult. Further research is needed to confirm how useful this technique is.
Aftercare and patient advice
Once the nail has been trephined, the area should be gently squeezed to express the blood (Bache et al, 1998). A pressure dressing will continue to squeeze out the haematoma and help resite the nail on the nail bed (Goodman et al, 2002). The dressing is usually left in place for about two days.
Patients should be advised to keep the area clean and dry in order to minimise the risk of infection of the nail bed. This is particularly important if the decision has been made to trephine a nail with an underlying distal phalanx fracture.
The haematoma will usually grow out with the nail, but nail deformity and permanent abnormalities can occur (Kukula et al, 2003) and patients should be warned of this. Normally, preserving the intact nail root and nail bed will ensure growth of a normal nail, but if the bed is damaged and scarred all future nails will be deformed (Heim at al, 2000).
Subungual haematoma, an apparently minor injury, can be extremely painful. Trephining is an effective method of releasing trapped blood and relieving pain, but nurses should know the treatment options and possible pitfalls to provide optimum care for patients.