Pnuritus ani.

Pnuritus ani. 

Anal itch, also known as pruritus ani, is an irritating, itchy sensation around the anus (the opening through which stool passes out of the body). Anal itch is a symptom, not an illness, and it can have many different causes. In most cases, a person with anal itch does not have a disease of the anus or rectum. Instead, the itchy sensation is a sign that one or more of the following has irritated the skin in the area: 

There are two main types of anal itching:

Primary (idiopathic) pruritis ani: This type of anal itching has no obvious cause. It’s the most common type of pruritus ani.

Secondary pruritis ani: This type of anal itching may have many different causes. Causes may include infections, systemic diseases, contact dermatitis and other dermatological conditions.

Causes 

There are many different possible causes for having an itchy anus, such as:

• leakage of poo (stool) from the rectum as a result of diarrhoea, constipation, diet, food intolerance or tears in the rectum
• infections such as herpes, bacteria or tinea
• intestinal parasites such as threadworms. The itch is usually worse at night, and you might be able to see small, white worms that are around 8-13 mm long
• haemorrhoids (piles), warts, and in extremely rare cases, cancer of the anus
• excessive sweating
• a health condition like diabetes or underactive thyroid
• skin conditions like psoriasis and contact dermatitis, which can occur when your skin is irritated by soaps, creams or perfumed or bleached toilet paper
• a health problem like diabetes or underactive thyroid
• One of the most common causes of pruritis ani is overcleaning. Try to avoid using soap, shampoo or bubble baths in this area as they remove the natural protective oils. Long hot baths or showers can also be problematic.

Symptoms

In addition to anal itching, you may also experience:

• burning
• soreness
• visible redness
• swelling
• ulcers
• a rash

Diagnosis 

Pruritus ani is diagnosed on a normal examination of perianal skin apart from possible secondary excoriations and lichenification. The cause of secondary itchy anus is usually established on history and examination. Investigations may be required to confirm the cause.

• Skin swab for bacteriology
• Skin scraping for mycology
• ‘Sticky tape’ test for pinworm ova
• Patch testing for allergic contact dermatitis
• Skin biopsy for inflammatory disorders or skin cancer