This document discusses fistula in ano, which is commonly caused by a previous anorectal abscess. It describes the anatomy of the anal canal and lists common causes of fistula in ano such as obstruction of the anal gland or iatrogenic, Crohn's disease, or anorectal trauma. Clinical features include perianal discharge, pain, swelling, and bleeding. Assessment involves physical examination under anesthesia and investigations like digital rectal exam, anoscopy, and MRI. Management depends on the complexity and location of the fistula, and may involve laying it open, probing and setting, or an anorectal advancement flap.

1. Fistula In Ano
Kishore SR
Oman Medical College

2. Contents
• Anatomy
• Etiology
• Clinical features
• Assessment and Investigations
• Management

3. Anatomy of the Anal Canal

5. Etiology
• Obstruction of the Anal Gland
▫ In the vast majority of cases, fistula-in-ano is caused by a previous
anorectal abscess. (cryptoglandular infection)
• Iatrogenic
• Crohn’s disease
• Anorectal trauma
• Anorectal Carcinoma
• Others (radiation therapy, actinomycoses, tuberculosis, and
lymphogranuloma venereum secondary to chlamydial infection)

6. Clinical Features
• Patients often provide a reliable history of previous pain, swelling,
and spontaneous or planned surgical drainage of an anorectal
abscess. Signs and symptoms of fistula-in-ano, in order of
prevalence, include:
• Perianal discharge
• Pain
• Swelling
• Bleeding
• Diarrhea
• Skin excoriation
• External opening

7. Assessment and Investigations
• Physical examination under Anesthesia
is the mainstay of diagnosis.
• Digital rectal examination (DRE) may
reveal a fibrous tract or cord beneath
the skin
• Anoscopy is usually required to identify
the internal opening.
• Proctoscopy is also indicated in the
presence of rectal disease (e.g., Crohn
disease or other associated
conditions).
• MRI for high complex fistulas

8. • Goodsall’s Rule

9. Management
• Low lying fistulas can be simply laid
open and allowed to heal.
• In complex ones involving the
sphincter, it can be probed using a
lacrimal probe and seton is passed
and allowed to drain.
• A tighter seton will gradually cut
through the sphincters and allow to
heal behind the seton.

10. • High fistulas can be treated with an anorectal
advancement flap.

11. Thank you