Anal pruritus (also known as “pruritus ani”) is persistent itching of the skin around the anus. This desire to itch can be further exacerbated by increases in moisture, pressure, and rubbing caused by clothing and sitting. It is a benign condition but can cause intolerable discomfort. Regardless of cause, the problem is exacerbated by a self-escalating “itch-scratch-itch” cycle.
Figure 1. Anal Pruritus with redness and pain in the anal region
In over 75% of cases of pruritus, the cause of the pruritus is not known (i.e. idiopathic pruritus).
Skin conditions such as dermatitis or psoriasis also can irritate the anus and result in anal pruritus. These may respond to corticosteroid creams.
Anal itching can be caused by irritating chemicals in the foods consumed, such as those containing spices, hot sauces, and chilli.
Moisture due to excessive perspiration, frequent liquid stools (diarrhoea), or a degree of faecal incontinence where there is a weak anal sphincter leading to seepage can exacerbate this condition. Moisture can also result from an abnormal passageway communicating between the anus and external skin (anal fistula). A fistula brings contaminated and irritating fluids to the anal area. Moisture can also result from excessive mucous discharge, a common problem with haemorrhoids and rectal prolapse, where the mucous secreting mucosa of the anus drops below the anal sphincter (prolapses) .
Infection with pinworm is common in those with young children and household pets. Less common is infestation with scabies or mites. These can all be tested for with skin scrapings or the “sellotape test” which are then sent off for viewing under microscopy.
Yeast or fungal infections may occur if there is moisture around the anus. They more often occur in people who are immune-compromised including diabetics, transplant recipients, those taking chemotherapy, and those with HIV.
Anal cancer is uncommon, as are precancerous lesions (Bowen’s and Paget’s disease). However, when present, they may first present as a perianal itch. It is therefore important for your colorectal surgeon to examine the area, and on occasions a biopsy if required to exclude anal cancer.
Management must be directed at breaking the “itch-scratch-itch” cycle as well as identifying causes and irritants and treating or avoiding these. It is important to clean and dry the anus thoroughly and avoid leaving soap in the anal area. Cleaning efforts should include gentle showering without direct rubbing or irritation of the skin with either the washcloth or towel. After bowel movements, wet cleaning of the perianal region either with a bidet or with moist wipes may be preferable to toilet paper.
Scratching the affected area is to be resisted, as it only aggravates the problem and can lead to bleeding from the anal area.
Synthetic underwear should be avoided. Irritant washing powders can also aggravate the problem.
A gauze pad or combine, folded in half and placed between the buttocks so that it is in close proximity to the anus, is an effective way of reducing moisture to the region.
BABY WIPES OR BIDET
Baby wipes may be preferable to abrasive toilet paper and can help reduce friction, however perfumed baby wipes should be avoided.
The French bidet used to wash the anal region after a bowel movement is an alternative to baby wipes. The conventional toilet can also have a bidet appliance attached to it.
Anal pruritus is often exacerbated by watery stools. A tablespoon or sachet of ispaghula husk (Metamucil® or Fibogel®) twice a day, can firm loose stools.
TOPICAL CREAMS AND OINTMENTS
There are many over-the-counter creams or ointments that can be applied to the anus to reduce itch. Most of these creams have a barrier compound such as petroleum jelly (Vasoline®) or zinc oxide that acts as a protectant and should be applied as a thin film to avoid excessive moisture. In addition they usually contain a small amount of one or more active ingredients. The active ingredients include an antiseptic (chlorhexidine), a local anaesthetic agents (lignocaine, benzocaine, cinchocaine) that numb the area, corticosteroids (hydrocortisone, fluocortolone, prednisolone) that reduce inflammation in the area, and vasoconstrictors (adrenaline) that make the blood vessels in the area become smaller, which may reduce swelling and help dry the area.
Most creams just contain a corticosteroid with a local anaesthetic (Proctosedyl®, Rectinol HC®, Scheriproct®, Ultraproct®), others contain a vasoconstrictor with local anaesthetic (Rectinol®). Some creams have all four active ingredients.
Antihistamines have been shown to reduce itch. However most are sedative, and are best taken in the evening.
Stronger 1% corticosteroid ointments containing hydrocortisone (Egorcort® Sigmacort®) betamethasone (Diprosone®) may be obtained with a prescription, and have been shown to reduce inflammation and relieve itching [2-3]. They should not be used long term (i.e. more than a few days to two weeks), as chronic use can cause permanent damage to the skin.
Topical capsaicin cream (Zostrix) is a novel agent that has achieved success rates of up to 70%. It causes a low grade burning sensation, that over time, produces inhibitory neural feedback at the spinal cord level which decreases the perception of itch. It comes in a 45g .075% and 0.05% and .025% strength and is quite affordable costing approximately $20.00-$25.00.
ANAL TATTOOING WITH METHYLENE BLUE
For severe intractable cases that have not responded to the above measures, anal tattooing with intradermal injection of methylene blue has been described with success rates of 80%. Significant adverse outcomes including skin necrosis have been reported. Good results, free of complication, have been achieved with a more dilute injection of methylene blue mixed with local anaesthetic agent and steroid . The mechanism of action is thought to be due to destruction of nerve endings in the peri-anal skin.
INVESTIGATIONS FOR PERSISTENT ITCHING
For persistent anal itching, efforts are directed toward identifying an underlying cause. An examination by your GP can rapidly identify most causes of anal itching. Adjustments in diet, treatment of infections, or surgical procedures to correct the underlying cause may be required.
WHAT TO EXPECT PRE AND POST OPERATIVELY FOLLOWING ANAL TATTOING
Fasting & Bowel Preparation
Unless you are also having a colonoscopy, a normal diet without bowel preparation, is required the day before surgery. You need to fast from midnight the night before if your surgery is scheduled for the morning, or from 7am if scheduled for the afternoon. You will be admitted as a day-stay procedure.
Recovery & transport
Following your procedure, you will recover for a hour until the effects of sedatives have worn off. You should not drive yourself home after your procedure and should have someone organised (a friend or relative) to accompany you.
Spotting of blood will occur from the injection sites. Blue discoloration to the perianal region will persist for some time. A sanitary napkin will be needed to prevent staining of your underwear.
For pain, a non-steroidal is recommended such as 400mg of ibuprofen (Brufen®) along with 2 tablets of paracetamol. This should only be taken if needed, and can be taken up to three times a day for five days. Opioid medications (Endone®) may sometimes be needed, but should be used sparingly as they cause constipation.
Excessive cleaning or scratching with abrasive toilet paper should be avoided. Washing with water or using baby wipes is preferable.
You should follow up with your colorectal surgeon in 6-8 weeks following your surgery to review your condition and discuss further management if indicated.