Incision & Drainage of Abscess

WHO Sign In

Before induction, confirm patient identity, consent, the marked site, allergies and that anaesthetic equipment is ready. Abscesses are commonly associated with diabetes, confirm status and check glucose.

• Bloods: FBC, CRP, glucose, check HbA1c (undiagnosed diabetes is very common in abscess presentations), U&E.
• Blood cultures if systemically unwell (temp >38°C, HR >90, WCC >12).
• USS if deep or uncertain, differentiates cellulitis from collection and identifies a multi-locular abscess.
• MRI pelvis if complex perianal sepsis is suspected.
• Mark the site pre-operatively.
• IV antibiotics only if systemically unwell (co-amoxiclav, or piperacillin-tazobactam if immunocompromised), antibiotics do not replace surgical drainage.

Brachial plexus & axillary vessels

Lie deep to an axillary abscess. At risk with blind deep dissection beyond the cavity walls, stay within the abscess cavity during deloculation and never probe beyond the walls.

External anal sphincter

Voluntary striated muscle surrounding the anal canal. Fistulotomy risks dividing the sphincter and causing permanent faecal incontinence, never perform fistulotomy at first presentation; place a loose seton and refer to colorectal.

Intercostobrachial nerve

Crosses the axilla and provides sensation to the upper inner arm. At risk during dissection of an axillary abscess, stay within the cavity and avoid wide lateral dissection.

Vas deferens & testicular vessels (perianal/scrotal)

At risk in large ischiorectal or scrotal abscesses; Fournier’s gangrene can involve scrotal structures. If there is crepitus or spreading necrosis, this is Fournier’s, not a simple abscess, escalate immediately.

Early

• •Incomplete drainage, the most common error (incision too small, loculations missed)
• •Wound infection / cellulitis
• •Bleeding
• •Recurrence from premature skin closure
• •Faecal incontinence if fistulotomy performed inappropriately (perianal)
• •Fournier’s gangrene, rare, life-threatening; return to theatre immediately if suspected

Late

• •Fistula-in-ano, up to 50% after a perianal abscess
• •Chronic pilonidal sinus requiring definitive excision
• •Hidradenitis suppurativa progression (axillary I&D is temporising only)
• •Scarring and chronic wound
• •Recurrent abscess, especially in diabetics, immunocompromised, or Crohn’s

You perform I&D of a perianal abscess and identify a clear fistula tract during probing. What should you do?

What is the most common technical error when draining an abscess?

A 45-year-old man with poorly controlled type 2 diabetes presents with a perianal abscess. Which investigation is most important pre-operatively?

A patient returns 48 hours after perianal I&D with worsening perineal pain, scrotal swelling, and crepitus on examination. What is the diagnosis?

Which position is used for pilonidal abscess drainage?

Immediate

• ›Regular paracetamol + ibuprofen
• ›Leave packing in situ, do not disturb for 24–48 hours
• ›Arrange dressing changes before discharge (district nurse, GP practice nurse, or stoma nurse for complex wounds)

Discharge

• ›Most patients same day
• ›Discharge with wound care instructions
• ›Laxatives if perianal (to soften stool)
• ›Antibiotics ONLY if systemically unwell / diabetic / immunocompromised / facial or hand abscess (co-amoxiclav 5 days)
• ›Safety-net: return immediately if fever + worsening pain + crepitus (Fournier’s), spreading redness, or inability to open bowels

Follow-up

• ›Wound check 1–2 weeks
• ›Pilonidal, review at 6 weeks; hair removal advice; consider referral for definitive excision if recurrent
• ›Perianal, colorectal outpatient follow-up if a fistula was identified
• ›Histology review for all specimens

Sick note

• ›Office work 1–2 weeks
• ›Manual labour 2–4 weeks
• ›Perianal wounds may take 6–8 weeks to fully heal with dressing changes throughout