Anal Pruritus

Anal pruritus (also known as “pruritus ani”) is persistent itching of the skin around the anus. It affects 1- 5% of the population with men more often affected than women. Many present late due to severe embarrassment. It is important not to trivialise the symptoms of this debilitating condition.

This desire to itch can be further exacerbated by increases in moisture, pressure, and rubbing caused by clothing and sitting. Regardless of cause, the problem is exacerbated by a self-escalating “itch-scratch-itch” cycle.

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Over time chronic pruritus due to scratching leads to lichenifucation (thickening) of the skin with leathery induration. Radial grooves cracks or ulcers can develop.

CAUSES

Idiopathic

Pruritus ani can be divided into two types: secondary to another condition, and idiopathic, which cannot be attributed to a specific cause [1]. Ideopathic pruritus accounts for more than 50% of patients with this condition.

Dermatitis

Skin conditions such as dermatitis, psoriasis and lichen sclerosis have typical plaque appearance and also can irritate the anus and result in anal pruritus. These need to be considered in the differential diagnosis and usually respond to corticosteroid creams. Sometimes punch biopsy is required to get a definitive diagnosis .

Foods

Anal itching can be caused by irritating chemicals in the foods consumed, such as those containing spices, hot sauces, and chilli. Excesses in caffeine can also stimulate secretions and bowel function causing loose motions, thereby exacerbating pruritus ani.

Moisture

Moisture due to excessive perspiration, frequent liquid stools (diarrhoea), or a degree of faecal incontinence or anal 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 and/or rectum drops (prolapses) below the anal sphincter allowing mucous contact with the perianal skin. This mucous is extremely irritant to the skin and causes intense itching. Large external skin tags and external component of haemorrhoids can also interfere with perianal hygiene, exacerbating pruritus ani.

Infections

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 and give a characteristic white film appearance overlying the skin. They more often occur in people who are immune-compromised including diabetics, transplant recipients, those taking chemotherapy, and those with HIV. A simple wound swab or scrapings will confirm the presence of hyphae (fungus) on microscopy. Treatment is topical 1% clotrimazole (Canesten®) or 1% terbinafine (Lamisil®) cream.

Anal Cancer

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 of any suspicious area may be needed to exclude anal cancer.

TREATMENT

Some colorectal surgeons take a nihilistic approach to the management of pruritus, considering it “incurable”. This is not the case and there is hope even for the most belligerent of cases. Treatment needs to be aimed at identifying & treating reversible causes, and getting severe intractable cases out of the itch-scratch cycle. Correcting maladaptive behaviour with the provision of clear achievable supportive guidelines plays an important role.

Cleaning

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. A “dabbing” action rather than “rubbing” action should be used for drying. Use of a hair dryer is also an option.

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. Even supposed “flushable” wipes have the potential to block sewer pipes with simple water the best option.

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. If bidet or wipes are not available or convenient, water or sorbolene cream or water based lubricant placed on toilet paper before wiping will reduce abrasion.

Behaviour modification

A small group with pruritus ani may have a degree of obsessive compulsive personality, and this group may require more targeted cognitive behaviour therapy to avoid ritualistic repetitive cleaning practices.

An even smaller group may have acquired their chronic itch through ano-neurotic acts of pleasure. To be fair, everyone with an itch gets immediate pleasure or relief in scratching. It must be emphasised that scratching the affected area is to be resisted, no matter how tempting it may be, as it only aggravates the problem and can lead to bleeding from the anal area and a delay in the recovery process.

Underwear

Synthetic underwear should be avoided. Firm supportive cotton underpants are recommended. Initially these may need to be changed more often then once daily if there is significant perianal moisture or exudate. The alternative is to line underwear with an adhesive thin panty liner. 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.

Bulking agents

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. Ointments contain petroleum jelly (Vasoline®) as the barrier compound, whereas creams are non-oily water based and may contain zinc oxide. These both act as a skin protectants and should be applied as a thin film to avoid excessive moisture. Zinc oxide on its own (Calmoseptine®) comes as both a cream and ointment. There are also numerous nappy rash creams. Bepanthen® contains vasoline, almond oil and dexpanthenol (Provitamin B5)

In addition, these products usually contain a small amount of one or more active ingredients. The active ingredients include an antiseptic (chlorhexidine), a local anaesthetic agent (lignocaine, benzocaine, cinchocaine) that numbs the area, corticosteroids (hydrocortisone, fluocortisone, prednisolone) that reduce inflammation, and vasoconstrictors (adrenaline) that make the blood vessels in the area become smaller, which may reduce swelling and help dry the area.

Products that contain a corticosteroid with a local anaesthetic include Proctosedyl®, Rectinol HC®, Scheriproct®, Ultraproct®. Others contain a vasoconstrictor with local anaesthetic (Rectinol®).

Antihistamines

Antihistamines have been shown to reduce itch[2]. However, most are sedative, and are best taken in the evening. These can be particularly useful for nocturnal itch.

Corticosteroid ointments & creams

Stronger 1% corticosteroid ointments or creams containing hydrocortisone (Egorcort® Sigmacort®) betamethasone (Diprosone®) may be obtained with a prescription, and have been shown to reduce inflammation and relieve itching [3-4]. 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

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[5]. It comes in a 45g with 0.025% the standard strength sold as Zostrix®, 0.075% strength (Zostrix HP®) and is quite affordable costing approximately $20.00-$25.00.

Methylene Blue Tattooing

There is good evidence for high success rates with methylene blue tattooing for even severe intractable cases of idiopathic pruritus ani that have not responded to the above conservative measures[6]. An initial Australian study described high satisfaction rates in over 96%, with complete resolution after a single treatment in 57%[7]. Salvage treatment with an additional tattooing at 1 month in non responders is recommended [8]. A more recent South Korean long term follow up study of 63 patients at 3 years using a more dilute form of methylene blue (5 ml of 1% methylene blue mixed with 15 ml of 1% lidocaine) showed success rates of 92.5% following methylene blue tattooing. [9]. Steroid can also be added to the mix [10]. The mechanism of action is thought to be due to destruction of nerve endings in the peri-anal skin. The potential risks of methylene blue include skin necrosis and the very rare case of anaphylaxis has been reported [11]. Therefore tattooing with methylene blue should occur in a hospital facility with full resuscitative support available.

What to expect before and after having anal tattooing?

Fasting and 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 and 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.

Bleeding

Spotting of blood will occur from the injection sites. Blue discoloration of urine and to the perianal region will persist for some time. A sanitary napkin will be needed to prevent staining of your underwear.

Pain

For pain, a non-steroidal is recommended such as 400mg of ibuprofen (Brufen®) along with 2 tablets of paracetamol (Panadol®). This should only be taken if needed, and can be taken up to three times a day for five days. Stronger pain killers such as tapentadol (Palexia IR®) may be required in the first 24 hours. Strong opioid medications such as oxycodone (Endone®) are rarely needed, and should be avoided or used sparingly as they highly addictive and cause constipation. Where a chronic neuropathic component to the itch is present, atypical agents such as amitryptyline (Endep®) or pregabalin (Lyrica®) may be indicated.

Cleanliness

Excessive cleaning or scratching with abrasive toilet paper should be avoided. Gentle washing with water or baby wipes is preferable.

Follow-up

You should follow up with your colorectal surgeon in 3-4 weeks following your surgery to review your condition and discuss further management if indicated. Occasionally non-responders require a second tattooing at one month to achieve relief [8].