Perineal Abscess + Fistula

Question 1

What is a Perineal Abscess?

Answer 1

A pus collection in the perineal region (surface region between pubic symphysis + coccyx)

Question 2

What is a Perineal Fistula?

Answer 2

an abnormal chronically infected tract communicating between the perineal skin + either the anal canal or rectum

Question 3

What causes a perineal abscess?

Answer 3

Bacterial infection

Question 4

What causes a perineal fistula?

Answer 4

Fistulae develop as a complication of an abscess

Question 5

List 4 risk factors for development of perineal abscesses and fistulas

Answer 5

IBD
Diabetes mellitus
Malignancy
Diverticulitis

Question 6

Multiple Perineal fistulae can develop as a complication of which disease? What is this called?

Answer 6

Crohn’s disease

Pepper pot perineum

Question 7

Describe the epidemiology of perineal abscesses and fistulae

Answer 7

COMMON

Question 8

Give 2 symptoms of perineal abscesses and fistulae

Answer 8

Constant throbbing pain in the perineum 
Intermittent discharge (mucus or faecal staining) near the anal region

Question 9

What may be present in the history of a patient presenting with perineal abscesses and fistulae?

Answer 9

Personal hx / FH of IBD

Question 10

List 3 signs of perineal abscesses and fistulae on examination

Answer 10

Localised tender perineal mass (may be fluctuant)
Small skin lesion near the anus (opening of the fistula)
Painful hardened tissue felt

Question 11

Describe DRE findings in perineal abscesses and fistulae

Answer 11

A thickened area over the abscess/fistula may be felt

DREs not always possible due to pain + anal sphincter spasm

Question 12

What is Goodsall’s Law?

Answer 12

Rule to correlate location of internal fistula opening based on location of external fistula opening
External opening ANTERIOR to anal canal (i.e. anterior to transverse anal line); fistula runs radially + directly into anal canal
External opening POSTERIOR to anal canal or 3 cm away follows a curved path + open internally in the posterior midline

Question 13

What bloods should be taken for perineal abscesses and fistulae?

Answer 13

FBC
CRP
ESR
Blood culture

Question 14

What may be assessed on MRI in perineal abscesses and fistulae?

Answer 14

Fstular tracts
Opening + closing of any fistulas
Location of deep abscesses
Damage to the anal sphincter

Question 15

What treatment is required for perineal abscesses and fistulae?

Answer 15

SURGICAL tx

Open Drainage of Abscess

Question 16

How are low fistulae managed?

Answer 16

Fistulotomy

Care must be taken to prevent damage to the anal sphincter

Question 17

How are high fistulae managed?

Answer 17

Seton: a non-absorbable suture that is threaded through the fistula to allow it to stay open + therefore drain
OR
Advanced flap procedure: cutting or scraping out the fistula + covering the hole where it entered the bowel with a flap of tissue taken from inside the rectum
OR
LIFT procedure: fistula sealed at both ends
OR
Endoscopic ablation to seal the fistula
Abx

Question 18

What is the prognosis for patients with perineal abscesses and fistulae?

Answer 18

High recurrence rate without complete excision

Question 19

What investigation may be performed to exclude differentials of suspected anal abscesses and fistulae?

Answer 19

Proctosigmoidoscopy