Anal Fistulas Flashcards
Definition
Anal fistulae are abnormal communications, hollow tracts lined with granulation tissue connecting the primary opening inside the anal canal to a secondary opening in the perineal skin. They are usually associated with anorectal abscesses (obstruction of ducts leading to infection).
Clinical Presentation
- Intermittent purulent discharge ± bleeding
- Pain – which increases till temporary relief occurs with pus discharge
Associated conditions
- Crohn’s disease
- Unusual Infection (i.e. TB, Actinomycosis, Chlamydia, HIV)
- Systemic disease (i.e DM)
- Hidradenitis suppurativa
- Malignancy
- Radiation
- History of trauma to anal region
PE
- Assess for external opening on perineum seen: may be open, covered in granulation tissue
- Assess for fibrous tract that can be felt underneath skin on DRE
What is Goddsall’s Rule
Goddsall’s Rule
- For fistula within 3cm of the anal verge and posterior to line drawn through ischial spines if
▪ Anterior to transverse anal line: straight radially directed tract into anal canal
▪ Posterior to transverse anal line: curve tract open into anal canal midline posteriorly (at level of dentate line)
- Exception: anterior external opening is >3cm from the anal margin – such fistula usually tack to the posterior midline
What is the classification
What investigations?
- Endoanal U/S (H2O2 aided for hyperechoic effect) – to view course of fistula tract – more accurate than Goodsall’s Rule
- MRI – able to visualise entire pelvis, beyond the sphincter complex (gold standard)
- CT/fistulography (in emergency situation) – for complex fistulas / unusual anatomy
What is the management?