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03 / Colorectal Surgery · open

EUA and drainage of perianal sepsis

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.

Part of Colorectal Surgery →4 stages3 complications to knowopen

On the tray for this operation

Test yourself on the tray

Stage

1 / 4

Examination under anaesthesia

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

Watch for: Missing a supralevator or horseshoe extension

Why are we operating?

Incision and drainage of a perianal abscess does the one thing antibiotics cannot: it opens a closed space under pressure. The operation is quick and the judgement is everything around it, examining under anaesthesia to map the sepsis, draining completely without harming the sphincters, and resisting the temptation to fix in pus what should be staged in peace.

Pulls toward surgery

Perianal or ischiorectal abscessSevere perianal pain with fever, even without obvious fluctuanceSepsis in the diabetic or immunosuppressed perineum (front of the queue)Recurrent abscess suggesting an underlying fistula

Gives the team pause

Necrotising infection wearing an abscess's storyCrohn's disease changing every operative instinctThe sphincter: spendable exactly once

What the surgeon is thinking

  • Examination under anaesthesia

    Why is the examination under anaesthesia the real diagnostic test?

    Awake examination of a septic perineum is limited by pain and mercy: under anaesthesia the abscess's true extent, its relation to the sphincters, and any internal opening can be assessed properly. Deep ischiorectal and supralevator sepsis can look almost normal from outside, which is why severe pain plus fever earns an EUA even with an unimpressive surface.

  • Incision and drainage

    What makes a drainage adequate?

    An opening big enough, close enough to the anal verge (shortening any future fistula), with loculations gently broken and the cavity left unable to reseal: pus re-accumulates behind small, polite incisions. Cultures matter in the diabetic, the recurrent and the strange.

  • The fistula decision

    A probe finds an internal opening. Why not fix the fistula now?

    Because acute inflamed tissue lies to the probe and to the surgeon: tracks are friable, false passages are easy, and sphincter division decided in pus is regretted at leisure. A draining seton through an obvious track is the honest middle path; definitive fistula surgery belongs to a quiet, mapped, elective perineum.

  • Dressing and the plan

    What is the packing actually for?

    Haemostasis tonight, and open-wound healing after: the cavity must heal from its depths outward, not seal at the skin over persisting sepsis. Modern practice packs lightly or not at all after the first dressing; what is non-negotiable is review, because the questions (healing? recurrent? fistula?) have dates attached.

Decision points

  • Pain out of proportion, spreading induration, a septic patient: still just an abscess?

    • Treat as necrotising perineal sepsis

      Fournier's territory: broad antibiotics and radical debridement now, with the first operation opening what the infection has already claimed.

    • Simple drainage

      Only when the picture genuinely stays local: the underestimated perineum is this operation's fatal error.

    The perineum hides necrotising infection well: crepitus, dishwater fluid, and skin changes lagging the sepsis are the tells. The threshold question at every EUA is 'is this bigger than it looks?', asked before the small incision is made.

  • Antibiotics instead of, or as well as, the knife?

    • Drainage, with antibiotics as adjunct

      The treatment is the operation; antibiotics cover cellulitis, immunosuppression, prosthetics and systemic sepsis.

    • Antibiotics alone

      For cellulitis without a collection, and almost nothing else: pus under pressure does not read prescriptions.

    The specialty's oldest rule survives every new drug: where there is pus, let it out. Antibiotics alone convert a drainable abscess into a smouldering, recurring one, especially in the diabetic patient who could least afford the delay.

Leaving the OR

The handoff

Procedure
EUA and incision-drainage of right ischiorectal abscess
Findings
5 cm cavity, loculations broken; no internal opening identified; no necrosis
Wound
Left open, light dressing; cultures sent
Watch for
Fever persisting past 24h (undrained pocket), spreading induration, urinary retention

A fictional educational patient, handed over the way real ones are.

The postoperative course

  1. Day of surgeryDramatic pain relief is the norm and its absence is information; home the same day for most, with laxatives and analgesia.
  2. POD 1-7Dressings and warm baths; the wound looks worse than it feels and heals from the bottom up.
  3. Weeks 2-6Review with the fistula question open: persistent discharge suggests a track, mapped electively with MRI where needed.
  4. If recurrentRecurrence is a message, not bad luck: think fistula, Crohn's, or inadequate first drainage, and investigate accordingly.

Watch it done

Find EUA and drainage of perianal sepsis videos on YouTube

What can go wrong

Intra-abdominal abscessSurgical-site infectionPostoperative bleeding
Live this operation as a case →OR Prep this operationReview the instruments