Anal Itching
Differential Diagnosis
Common Diagnoses
- Fungal Infection: Tinea, Thrush
- Threadworms
- Haemorrhoids
- Perianal Skin Tags
- Anal Fissure
Occasional Diagnoses
- Poor Hygiene
- Recurrent or Chronic Diarrhoea
- Perianal Warts
- Streptococcal Perianal Infection in Children
- Trauma from Sexual Practices: Anal Intercourse and Foreign Body Insertion
- Faecal Incontinence, Including Liquid Faecal Seepage Round Impacted Stool
- Psoriasis
- Secondary to Underlying Diabetes
- Anorectal Carcinoma
- Chemical Irritation: Defaecation after a Very Spicy Meal (Commonly Experienced, Rarely Presented in Practice), Bubble Baths, Soaps, Sexual Lubricants
Rare Diagnoses
- Irritation from Perineal Decorative Body Piercing (the ‘Guiche’)
- Lichen Sclerosus et Atrophicus (Affects 1 in 100 Women, 3 in 10 of these Have Anal Symptoms)
- Crohn’s Disease (Anal/Perianal Fistula)
- Rectovaginal Fistula
- Rectal Prolapse
- Any Other Cause of Rectal Discharge or Anal Swellings
- Any Serious Cause of Generalised Pruritus – See Chapter on Anal Itching. Rare Here because Pruritus Ani is Unlikely to be a Presenting Complaint
- STDs, e.g. Syphilis, Gonorrhoea, Chlamydia
Ready Reckoner
Key distinguishing features of the most common diagnoses
| Fungal infection | Threadworms | Haemorrhoids | Skin Tags | Fissure | |
|---|---|---|---|---|---|
| Rectal Bleeding | No | Possible | Possible | No | Yes |
| Markedly Worse at Night | Possible | Yes | Possible | Possible | No |
| Complains of Lump | No | No | Possible | Possible | No |
| Rectal Discharge | No | No | Possible | No | Possible |
| Painful Defaecation | No | No | Possible | No | Yes |
Possible Investigations
Likely:None
Possible:Skin swab, FBC, ESR, fasting glucose or HbA1c, proctoscopy
Small Print:None
- In general, unless there are obvious pointers to other more serious disease, investigations would usually only follow after failure of empirical treatment.
- Skin swab for bacteriology may help identify local infection.
- FBC, ESR: May be helpful if Crohn’s disease is suspected, but only as an adjunct to referral as the appropriate management
- Fasting glucose or HbA1c is essential in recurrent or prolonged cases to exclude diabetes.
- Proctoscopy is quick to do in general practice and can yield valuable information if there is an underlying rectal cause.
Top Tips
- Most patients will have attempted self-treatment before presenting in the surgery. This may not always have been appropriate, and could have made the problem worse.
- Unless you are absolutely sure of an obvious cause, it is wise to perform a digital rectal examination to look for rectal causes
- Perianal warts imply a sexually transmitted disease contact. Refer to GUM clinic for contact tracing and treatment.
- Anal itching is often associated with soreness. If it precludes a rectal examination but there is no obvious primary anal cause for itching, treat symptomatically and bring the patient back to complete the assessment when more comfortable to do so. The patient is unlikely to want to return for this without understanding a clear explanation of why it is necessary
Red Flags
- Four percent of women with lichen sclerosus et atrophicus go on to develop vulval cancer. Refer if the vulva is affected, or if treatment fails
- Refer any suspicious anal lesion for biopsy.
- Be confident to ask about recent sexual encounters and sexual practices if possibly relevant. Sexual history may be important.