Perineal abscesses and fistulae

Question 1

Define:

Answer 1

Perineal abscess - a collection of pus in the perineal region

Perineal Fistula - abnormally chronically infected tract communicating between the perineal and the anal canal or rectum

Question 2

Aetiology:

Answer 2

Bacterial infections

Fistula form as a complication of abscesses or as a complication of Crohn’s (multiple fistulae in Crohn’s is known as pepper pot perineum)

Question 3

Risk factors:

Answer 3

IBD
Diabetes mellitus
Malignancy

Question 4

Symptoms:

Answer 4

constantly throbbing pain in perineum

Intermittent discharge (mucus or faecal staining near the anal region)

Personal or family history of IBD

Question 5

Signs:

Answer 5

Small skin lesion the perineal area (opening of the fistula)

localised tender perineal mass (may be fluctuant)

DRE (may to be painful to carry out but may show thickening of skin above the fistula/abscess)

Goodsall’s law (this helps to estimate the location of the internal opening of the fistula based on the external –> If it is anterior in the perineum it will open straight into the anal canal. If it is posterior or 3cm away it will be a curved line to the posterior midline)

Question 6

Investigations:

Answer 6

Bloods:

• CRP
• ESR
• FBC
• Blood culture

Imaging:

• MRI
• Endoanal US (less useful)

Question 7

Management:

Answer 7

needs surgical intervention

Abscesses need open drainage

laying open of the fistula - probe inserted to explore the fistula (dye interested at external opening to locate internal opening)

Low fistula- fistulotomy

High fistula - Seton (non-absorbable suture)
DO NOT DO FISTULOTOMY AS WILL LEAD TO INCONTINENCE

Question 8

Complications:

Answer 8

Recurrence

Incontinence

Damage to internal anal sphincter

persisting pain

Question 9

prognosis:

Answer 9

high recurrence rate without complete excision