What is pruritis ani?
Pruritis ani is a Latin term meaning "itchy anus". It is a condition which produces an irritation around the anus and the desire to scratch. Scratching of the perianal skin then causes further irritation and trauma to the sensitive skin around the anus over an even wider area, worsening the problem. Then more itching occurs and more scratching. This compounds the problem further. It can be difficult to break the cycle of itch-scratch-itch.
What are the causes of pruritis ani?
Pruritis ani can be primary or secondary. The primary form does not have an identifiable cause (idiopathic). The secondary form of pruritis ani can be caused by many, many conditions, including:
- Dermatitis of many varying forms
- Infections (bacterial, viral, fungal, parasitic) including sexually-transmitted and non-sexually transmitted infections
- Anorectal disorders such as haemorrhoids, mucosal prolapse, fissures, fistulas
- Malignant and pre-malignant diseases (anal cancer, anal intraepithelial neoplasia, BCC, Bowen's disease, Paget's disease, anal melanoma
What is the treatment of pruritis ani?
If an underlying condition can be found that started the itching cycle then treatment of this can be initiated. This may be as simple as assessing and treating for worms, or prescription of a topical antifungal to manage a yeast infection. Your specialist may request a stool sample and take a biopsy of the area. Careful inspection of the anus, rectum and perianal skin will be performed in the office, along with a digital rectal examination.
A brief trial of topical steroids can be helpful to break the itch-scratch cycle, however topical steroids should not be used long term as they thin the perianal skin increasing the risk of further skin breakdown.
A regular fibre supplement to help with passive of formed soft stool is generally recommended. Excessive wiping of the area after toileting is discouraged as this further traumatises the area. A shower or bath after a bowel motion is preferred. One should avoid the use of scented toilet paper and soaps.
Coffee and excessive alcohol are a common causes of pruritis ani, and reduction or elimination of these agents from the diet can cause dramatic improvements
For refractory cases, injection of a dye called methylene blue into the perianal skin can results in ablation of the nerve endings and resolution of symptoms. The injection is a cocktail of 20ml of 0.5% Marcaine with 1:200 000 adrenaline, 1 ml methylprednisolone (40mg/ml) and 10ml of 1% methylene blue. The solution is injected intra-dermally into the area of pruritis which has been marked pre-operatively.
