Perineal abscesses & fistula Flashcards
Define perineal abscess
Pus collection in perianal region
Define perineal fistula
Abnormal chronically infected tract communicating between the perineal skin & either the anal canal or the rectum
Aetiology of perineal abscess -> fistula
3
Bacterial infection
Fistula develops as complication of an abscess
Fistula can develop as complication of Crohn’s disease
Risk factors for perineal abscess/fistula
3
IBD
Diabetes mellitus
Malignancy
Epidemiology of perineal abscess/fistula
COMMON
Presenting symptoms of perineal abscess/fistula
3
Constant throbbing pain in perineum
Intermittent discharge (mucus or faecal staining) near anal region
Personal or FH of IBD
Signs of perineal abscess/fistula on physical examination
4
Localised tender perineal mass (may be fluctuant)
Small skin lesion near the anus (opening of fistula)
DRE
thickened area over abscess/fistula may be felt
may not be possible due to pain & anal sphincter spasm
Goodsall’s law
Goodsall’s law
define + 2
Rule allows estimation of location of internal fistula opening based on external opening
If external fistula opening is ANTERIOR to anal canal, fistula runs RADIALLY & DIRECTLY into anal canal
An external fistula opening 3cm away or POSTERIOR to the transverse anal line will follow a curved path & open internally in POSTERIOR MIDLINE
Investigations for perineal abscess/fistula
2
Bloods
Imaging
Investigations for perineal abscess/fistula - bloods
4
FBC
CRP
ESR
Blood culture
Investigations for perineal abscess/fistula - imaging
2
MRI
Endoanal US less useful
Management of perineal abscess/fistula
type + 1 + 4 + 1
Requires SURGICAL treatment
Open drainage of abscess
Laying open of abscess
Probe inserted to explore fistula
Dye can be inserted into external opening to allow you to find the internal opening
Low fistula
fistulotomy
care must be taken to prevent damage to anal sphincter
High fistula
fistulotomy would cause INCONTINENCE so not performed
seton (non-absorbable suture) is threaded through fistula to allow drainage
Antibiotics
Complications of perineal abscess/fistula
4
Recurrence
Damage to internal nail sphincter
Incontinence
Persisting pain
Prognosis of perineal abscess/fistula
High recurrence rate without complete excision
