Abscess Incision & Drainage

Assessment and technique for draining a cutaneous abscess in general practice and urgent care. See Local Anaesthesia for infiltration dosing and Cellulitis & Skin/Soft-Tissue Infection for the non-purulent end of the same spectrum.

Clinical presentation

A cutaneous abscess is a localised collection of pus in the dermis and subcutaneous space. It occurs anywhere on the body but most often in the groin, buttocks, axillae and extremities. The classic findings are erythema, induration, tenderness and fluctuance. Fluctuance is the feature that distinguishes an abscess from cellulitis, which is treated with antibiotics alone and does not need drainage. When overlying induration makes fluctuance hard to assess clinically, bedside ultrasound helps confirm the collection and its size before deciding to proceed.

Purulent infection — an abscess or boil — is typically caused by Staphylococcus aureus, including MRSA. Cellulitis surrounding a drained or draining abscess still needs the same organism coverage as any other purulent skin infection.

Indications and contraindications

Most abscesses need incision and drainage: antibiotics alone are not sufficient treatment for an established collection. A small fluid collection can sometimes be managed conservatively with antibiotics and manual expression instead.

Avoid bedside drainage, and refer instead, for:

• A large or deep abscess, or one with a pulsatile mass suggesting proximity to a major vessel.
• Perirectal or periareolar abscesses — surgical referral, given the risk of fistula formation.
• Neck abscesses that may have arisen from a pre-existing cystic lesion — refer for specialist assessment.
• Abscesses in technically difficult sites such as the palms, soles or face.
• A collection needing surgical drainage in a patient who is systemically unwell — this is an admission, not an outpatient procedure.

Before proceeding, ask about bleeding disorders and allergy to lidocaine, adrenaline or latex (if latex gloves will be used), and consider whether prophylactic antibiotics are needed first in a patient with an abnormal or prosthetic heart valve.

Equipment

Cleansing solution (povidone-iodine or chlorhexidine), local anaesthetic (1% or 2% lidocaine, with or without adrenaline), a syringe and fine needle for infiltration, gauze, a scalpel with blade, a curved haemostat for blunt dissection, normal saline with a syringe for irrigation, packing material if needed, swabs for culture, and dressing supplies. Oral or parenteral analgesia may be needed in addition to local anaesthetic — I&D is a painful procedure.

Technique

Infiltrate local anaesthetic around and over the abscess (see Local Anaesthesia for agent choice and maximum doses). Make the incision directly over the centre of the collection, parallel to skin tension lines to limit scarring, and continue until pus is expressed. Use a curved haemostat for blunt dissection to break up loculations within the cavity, and manual expression to complete drainage. Irrigate copiously with normal saline once drained.

Routine packing is not recommended for an abscess 5 cm or smaller — it has not been shown to improve outcomes or reduce recurrence, and adds pain. Reserve packing for larger cavities where haemostasis or continued drainage is a concern. Cover with a sterile dressing; the wound is then left to heal by secondary intention.

Loop drainage is an alternative technique — two small stab incisions at either end of the cavity with a vessel loop or similar drain threaded through — associated with less pain and scarring and a lower failure rate than conventional incision and packing, though it is less widely used and needs more practice to perform confidently. Needle aspiration is not recommended as a substitute for formal drainage: it is more invasive to perform well and considerably less effective, with roughly a third the success rate of incision and drainage at producing adequate drainage.

Wound culture

Send pus for culture and susceptibility, particularly where MRSA is a possibility — recurrent abscesses, prior MRSA colonisation, injecting drug use, close-contact settings — or where the patient does not respond to first-line empirical therapy.

Antibiotics

Drainage is the primary treatment. A small, uncomplicated abscess in an otherwise well patient can be managed with drainage alone.

Add antibiotics for any of:

• Surrounding cellulitis
• Systemic features — fever, tachycardia
• Significant comorbidity or immune compromise
• Multiple or recurrent abscesses
• A high-risk site: face, hands, genitals

Empirical choice should cover S. aureus, including MRSA where risk factors are present. Follow the current Therapeutic Guidelines skin and soft-tissue infection recommendations, and adjust to culture results.

Follow-up and safety-netting

Review at 2–3 days if packing was used, for removal and reassessment. A patient managed without packing should still return if pain, spreading erythema or fever develop.

Recurrent abscesses, particularly if MRSA-associated, warrant hygiene counselling (hand hygiene, not sharing towels or razors, covering wounds) and consideration of decolonisation (topical mupirocin, chlorhexidine washes) once drainage and any active infection have settled.