Colorectal

Anal Fistula Surgery — Seton Insertion

OPERATION: Examination Under Anaesthesia, Abscess Drainage and Seton Insertion for Complex Anal Fistula
ANAESTHETIC: General / spinal anaesthesia
POSITION: Lithotomy
ANTIBIOTICS: Broad-spectrum IV antibiotics if sepsis present

INDICATION:
Complex anal fistula — [high trans-sphincteric / suprasphincteric / horseshoe component]. [Associated ischiorectal abscess]. [Crohn's disease / recurrent fistula]. MRI pelvis: [findings — track level, relation to sphincters, presence of secondary extensions]. Continence assessed preoperatively — patient counselled regarding seton placement and staged approach.

PROCEDURE:
WHO Checklist performed. Perineum prepared and draped. Examination under anaesthesia — bidigital assessment of sphincter tone, fistula anatomy, and degree of induration.

[ABSCESS DRAINAGE: Ischiorectal / perianal abscess drained via dependent incision. Pus evacuated and sent for MC+S. Cavity irrigated.]

Fistula track probed from external opening. Internal opening identified at [position] by digital palpation of induration and by probing with an eyelet probe under direct vision. Internal opening at [position] at [dentate line / above dentate line].

Fistula assessed as [high trans-sphincteric] — sphincter preservation required given significant muscle involvement above the dentate line.

Seton (braided / silastic / vessel loop) inserted: eyelet probe passed from external to internal opening; seton looped through the track and brought out through the anus; tied loosely to maintain drainage. Seton secured without tension — positioned as a long-term draining seton [/ cutting seton — will be tightened progressively at outpatient visits].

External wound enlarged for dependent drainage. Track curetted and irrigated. Haemostasis confirmed.

FINDINGS:
[High trans-sphincteric / suprasphincteric / horseshoe] fistula with [ischiorectal abscess]. Internal opening at [position]. Significant sphincter involvement — seton approach chosen to preserve continence. Secondary track(s): [describe].

EBL: Minimal. COMPLICATIONS: None.

POST-OPERATIVE INSTRUCTIONS:
Regular analgesia. Sitz baths. Outpatient review at 6–8 weeks for seton assessment. Further staged procedure (LIFT / mucosal advancement flap / seton tightening) to be planned at MDT review. MRI pelvis at [6 months] to reassess track response.