EUA and drainage of perianal sepsis

Why are we operating?

The abscess around the anus: examine properly under anaesthesia, drain completely, and hunt the fistula gently or not at all.

Indication: Perianal or ischiorectal abscess; the diabetic patient with pain out of proportion is an emergency.

The operation in 4 steps

1. 01Examination under anaesthesia

   Inspection, palpation and proctoscopy with the patient relaxed, mapping induration and looking for an internal opening.

   Why: Awake examination of perianal sepsis is neither kind nor accurate. The EUA is the diagnostic half of the operation: it distinguishes simple abscess from horseshoe extension, and looks for the cryptoglandular origin most of these share.

2. 02Incision and drainage

   Cruciate or elliptical incision over the point of maximal fluctuance, close to the anal verge, pus cultured and loculations broken.

   Why: Keeping the incision near the verge keeps any future fistula tract short. Loculations are opened because an abscess drained in part is an abscess treated in name only.

3. 03The fistula decision

   If an internal opening declares itself, a loose draining seton may be placed; aggressive probing is avoided in the acute setting.

   Why: Half of these abscesses are the acute face of a fistula, but forcing a probe through inflamed tissue manufactures false tracts through sphincter. The seton drains and marks; definitive fistula surgery is an elective conversation.

4. 04Dressing and the plan

   The cavity is dressed open; the patient leaves with follow-up arranged and clear instructions.

   Why: These wounds heal from the base by secondary intention. The complication to prevent at discharge is the missed recurrence, so review is part of the operation.

Anatomy you need

The anorectum from above; the sphincter complex around it is what the drainage incision must respect.

What can go wrong

• Intra-abdominal abscess

  Swinging fevers, malaise, and localized pain from day 5 onward, classically after perforated appendicitis.

• Surgical-site infection

  Wound erythema, warmth, discharge, and pain out of proportion, typically from postoperative day 4–7.

• Postoperative bleeding

  Tachycardia first, hypotension late; falling urine output; a distending abdomen or rising drain output.