CKS Clinical Solutions - Pruritus ani

The case: A 55-year-old man presents complaining of a perianal itch for the past four to six weeks.

Haemorrhoids may cause pruritus (Photograph: Dr P Marazzi / Science Photo Library)
Haemorrhoids may cause pruritus (Photograph: Dr P Marazzi / Science Photo Library)

What is pruritus ani?
Pruritus ani is a symptom, defined as an unpleasant sensation to scratch the skin around the anal orifice.

Pruritus ani may be idiopathic (primary) or secondary to an identified cause.

How do I know my patient has it?
People usually have an irresistible urge to scratch the anus; more common after a bowel movement and at night. Itching may be exacerbated by heat, moisture, soiling, stress and anxiety.

What causes pruritus ani?
Primary pruritus ani has no identifiable cause, but is thought to be the result of small amounts of faecal leakage (with inadequate cleaning) and excessive moisture perianally.

Secondary pruritus ani may be caused by infections (such as candida, threadworms, scabies), gastrointestinal pathology (for example, fistula, fissure, piles); dermatological conditions (such as psoriasis, contact dermatitis); local malignancy; systemic disease and medications.

How should I assess the patient?
Ask about hygiene practices; irritants (creams and soaps); diet (citrus fruits and spicy foods); chronic diarrhoea; and increasing anxiety or stress. Then examine the perianal skin and perform a digital rectal examination to look for secondary causes.1,2

How should I manage pruritus ani?
Treat any underlying secondary cause. If no cause is identified, offer a soothing ointment (such as zinc oxide) if the skin shows excoriation; and a short course (five to seven days) of a mildly potent topical corticosteroid if inflammation is present.

Do not use topical corticosteroids long term as this may lead to contact dermatitis and skin atrophy. Consider giving a sedating oral antihistamine at night if the patient has disturbed sleep due to itching.3

What lifestyle advice should I offer?
Advise the patient to avoid irritants such as soap, perfumes, scented toilet paper, and topical medications. Explain to the patient to wash the perianal area gently with water after a bowel movement and at bedtime, and pat dry with a soft towel. If moisture is a problem, advise the patient to wear cotton underwear instead of nylon, or consider placing a cotton tissue on the area to absorb moisture throughout the day.3

If the patient can relate itching to certain food or drinks, then dietary avoidance may be of value.4 Otherwise advise a high-fibre diet and fibre supplements to keep stools soft, formed and regular, minimising faecal leakage.3

When should I refer someone with idiopathic pruritus ani?
If treatment for three or four weeks is unsuccessful, further investigations to exclude a secondary cause may be needed. Refer to a dermatologist, colorectal surgeon, or colorectal specialist nurse depending on the suspected underlying cause.3,5

Evidence
The evidence for the management of pruritis ani is poor; therefore CKS have based most recommendations on expert opinion. Case series have shown topical corticosteroids provide temporary relief of pruritus ani when inflammation is present.2 In addition, CKS identified one small RCT which showed hydrocortisone was more effective than placebo at reducing itch over a two-week period.6

References
1. Kranke B, Trummer M, Brabek E. Wien Klin Wochenschr 2006; 118(3-4): 90-4.

2. Hanno R and Murphy P. Dermatol Clin 1987; 5(4): 811-6.

3. Hardy A and Acheson AG. Surgery 2006; 24(4): 145-7.

4. Chardhry V and Bastawrous A. Semin Colon Rectal Surg 2003; 14(4): 196-202.

5. Dasan S, Neill SM, Donaldson DR. et al. Br J Surgery 1999; 86(10): 1337-40.

6. Al-Ghnanhiem R, Short K, Pullen A et al. Int J Colorectal Dis 2007; 22(12): 1463-7.

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