Pruritis Ani

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DEFINITION
Irritation / discomfort / itch of the anus that causes an urge to scratch.
Both a symptom and a diagnosis.

D I A B M I M

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INCIDENCE

Common 1-5% of people;
Primary / idiopathic in >50%.
M>F
most common 40-70y
Worse in hot humid climates.
D I A B M I M

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AETIOLOGY

Primary
Idiopathic
Diagnosis of exclusion; must rule out serious causes

Secondary

1. Anal precursors
May be initially incited by basically any other perianal condition:
Chronic diarrhoea
Chronic constipation
Colorectal or anal cancer
Haemorrhoids
Anal dyskinesia
Skin tags
Anal fissure
Adenomatous polyps
Rectal prolapse
Sphincter weakness
Fistula-in-ano
Fecal leakage / soiling
- exotoxins from stool can cause irritation and breakdown, then scratching begins...

These problems may cause irritation of nerve fibres, or scratching, initiating the vicious cycle.

2. Dermatologic precursors
Basically any perianal dermatological problem, e.g:
Psoriasis, seorrhoeic keratosis, integrigo
Dermatitis, atopy, vitiligo, Paget, Bowen
Also allergies: soaps, detergents, toilet papers, clothing
Also infective: staph, strep, herpes zoster
Parasites
STDs and anal warts

3. Food and Drug precursors
Coffee, tea, beer, chocolate
Colchicines, quinidine.
D I A B M I M

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BIOLOGICAL BEHAVIOUR

Pathophysiology
Intense itch mediated by nociceptive C fibres; high density at dermal-epidermal jx.
Irritants such as histamine, kallikrein, bradykinin, serotonin, prostaglandins --> stimulated.
- pain fibres but conveyed to thalamus; perceived as itch.

When scratched, skin breakdown occurs
--> vicious cycle; worse irritants, worse pruritis, worse impulse to scratch.
Can lead to social embarrassment.

D I A B M I M

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MANIFESTATIONS

Symptoms / Signs
Intense itchiness
Burning sensation in perianal skin.
Scratching makes it worse
- and results in excoriation, bleeding, pain.
Often the pt tries to make it worse with regular cleaning
- unfortunately this also makes it worse.

Inquire as to:
- toilet habit, problems.
- perianal hygeine
- perianal problems
- over the counter meds
- diet
- incontinence

Examine under bright light.
Anoscopy
Proctoscopy
Get them to strain
--> reveals haemorrhoids,prolapse, other secondary causes of perianal irritation
Inspect lymph basis for chronic inflammation / infection node reaction.

D I A B M I M

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INVESTIGATIONS

Clinical
As per suspected causes.
top D I A B M I M P home

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MANAGEMENT

1. Treat any underlying causes.

2. Key Principle
Interrupt the vicious cycle.

3. Reassure and educate
- toilet habits, diet (remove potential inciting foods one by one at 2 week intervals)

4. Simple remedies
- anal drying lotions, anti-inflammatories

5. Remove all possible irritants
- stop using soaps / lotions.
- avoid scrubbing / scratching.
- don't be fastidious with hygeine thinking it will help; it will be making it worse.
- instead, gently clean bd with plain showers and no chemicals.

6. If reqd : control seepage and leakage
- bulking agents, high-fibre diet
- antimotility agents may prolong transit.

If not successful, move to next level:

7. Topical hydrocortisone may help in more extreme cases.
- controversial but bottom line is do not use for extended periods; 1 week then taper down
- else atrophy of perianal skin may result, breakdown and worse problems
- introduce a barrier cream during this time.

8. Topical capsaicin has been shown to possibly work in small trials.

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