An abscess is a collection of pus in the soft tissues most commonly due to Staphylococcus aureus.
During the suppurative stage, a ‘ripe’ abscess is red, inflamed, painful, shiny and swollen. It is usually fluctuant on palpation and may be fistulated. At this stage, the abscess cavity is inaccessible to antibiotics and surgical drainage is the only effective treatment.
During the early indurated stage, that precedes the suppurative stage, medical treatment may be effective.
Children: 30 mg/kg 3 times daily
Adults: 1 g 3 times daily
+ metronidazole PO
Children: 10 to 15 mg/kg 3 times daily
Adults: 500 mg 3 times daily
amoxicillin/clavulanic acid (co-amoxiclav) PO
Use formulations in a ratio of 8:1 or 7:1 exclusively. The dose is expressed in amoxicillin:
Children < 40 kg: 50 mg/kg 2 times daily
Children ≥ 40 kg and adults:
Ratio 8:1: 3000 mg daily (2 tablets of 500/62.5 mg, 3 times daily)
Ratio 7:1: 2625 mg daily (1 tablet of 875/125 mg, 3 times daily)
– Adapt analgesics to the pain level (see Pain, Chapter 1).
– Apply compresses soaked with warm water 2 to 3 times daily.
If there is improvement after 48 hours: continue antibiotherapy for 5 days to complete 7 days of treatment.
If there is no improvement after 48 hours of correct treatment: treat surgically.
– Sterile scalpel handle and blade
– Sterile curved, non-toothed artery forceps (Kelly type)
– Sterile gloves
– 5 or 10 ml syringe
– Non-absorbable sutures
– Sterile corrugated drain
With the exception of paronychia, local anaesthesia of the abscess is usually impossible. General anaesthesia may be indicated, using:
ketamine IM: 10 mg/kg
Incision (Figure 8a)
– Hold the scalpel between the thumb and middle finger of the dominant hand, the index finger presses on the handle. Hold the abscess between the thumb and index finger of the other hand. The scalpel blade should be perpendicular to the skin.
– The incision is made in a single stroke along the long axis of the abscess. The incision must be long enough for a finger to be inserted.
– Be cautious when excising an abscess located over a blood vessel (carotid, axillary, humeral, femoral, popliteal).
Digital exploration (Figure 8b)
– Explore the cavity with the index finger, breaking down all loculi (a single cavity should remain), evacuate the pus and explore to the edges of the cavity.
– The exploration also allows an assessment of the extent of the abscess, the depth, and location with respect to underlying structures (arterial pulsation) or any possible contact with underlying bone. In this last case, seek surgical advice.
Abundant washing of the cavity using a syringe filled with antiseptic solution.
Drainage (Figure 8c)
Insert a drain (or, failing that a gauze wick) into the base of the cavity. If possible, fix it to the edge of the incision with a single suture. The drain is withdrawn progressively and then, after 3 to 5 days removed completely.