Topical anal preparations

Conditions of the anal canal and surrounding skin are a common cause of complaint. Topical anal preparations are readily available, easy to apply and often work well. There are pitfalls for the general practitioner to be aware of, as not all symptoms are due to `my haemorrhoids, Doctor'.

Perianal symptoms are limited to pruritus, bleeding, pain, discharge or a lump. The list of potential causes of these symptoms is very large and ranges from the innocuous to the lethal. Patients typically blame `haemorrhoids' for any of these symptoms and are encouraged to do so by the plethora of generic `haemorrhoid' medications available.

Taking the history helps with the differential diagnosis. Any complaint of `haemorrhoids' is a concern. No patient directs their doctor's attention lightly to such an embarrassing area. The general practitioner understands that perianal symptoms can be due to anything from a mildly prolapsed anal cushion (haemorrhoid) causing mucus leakage, excoriation and pruritus, to a malignant melanoma of the anal canal. The perianal skin may be the place where a systemic disease such as diabetes, psoriasis or candidiasis first appears. Sexually transmitted diseases need to be considered as does pin worm. Inflammatory bowel disease, incontinence and irritable bowel syndrome can all add their confounding influence.

If the history is vital, careful physical examination is even more so. Do not defer examination. Have the patient lie in the left lateral position with buttocks over the edge of the bed. Inspect the area with a good light. Use two hands to gently but resolutely separate the buttocks, noting the condition of the skin. Look for dermatitis, ulceration, excoriation, a lump or a discharging sinus. Efface the anal canal and you may glimpse prolapsing mucosa or a fissure. For the digital examination, use firm pressure over the perineum and wait for the reflex contraction to relax before slowly inserting the index finger. Use plenty of lubrication. You may feel a lump. Note whether the rectum is full or empty. Ask the patient to squeeze onto your finger and assess the length and strength of the sphincter. Look for blood on the gloved finger. Do not persevere if there is pain, as an examination under such conditions will yield little or no useful information; the patient may need an examination under anaesthetic.

The rectum should be visualised with a rigid or flexible sigmoidoscope to rule out neoplasm and inflammatory bowel disease. Guidelines for colonoscopy in patients with rectal bleeding are well established and should be considered.

Do not prescribe any topical anal preparation without establishing ground rules for basic perianal skin care. The goal of treatment should be the establishment of healthy, supple skin, resistant to moisture and trauma. Do not underestimate the efficacy of a deep, comfortably warm bath to relieve perianal symptoms.

Rational patients (and their doctors) would never consider treating a mosquito bite or graze by rubbing it regularly with soiled toilet paper, yet this is how they treat their perianal skin and wonder why their symptoms persist. Moist, macerated and cracked skin is a poor barrier to irritants. Encourage patients to refrain from using toilet paper. They should wash their perineum in a bath or shower after bowel movements. If this is not practical, moist towels (sold for nappy changes) are preferable to toilet paper. Next, they should apply a thin layer of a barrier ointment to protect the skin from the moisture which is inevitable in that area (zinc and castor oil is cheap and readily available).

Unfortunately, the anal canal cannot be separated from the colon and rectum for purposes of topical treatment. The rectum is not a good storage organ and the anal canal and perianal skin suffer when defecation is consistently deferred or incomplete (a frequent requirement of the modern lifestyle). The internal anal sphincter responds to increased rectal pressure by relaxing (sampling reflex). Small amounts of mucus leak onto the skin of the lower anal canal causing maceration. It is hopeful thinking to consider that a topical preparation can compensate for the long-term frustration of a phenomenon as basic as the gastrocolic reflex.

Topical treatment

Common topical anal preparations include local anaesthetics, steroids and antibiotics. Most successful formulations include all three in various combinations.

Local anaesthetics mask pain and pruritus. They are useful for acute conditions such as thrombosed external haemorrhoid or acute fissure, but prolonged use should be discouraged. Skin sensitivity can occur.

Steroids inhibit the local inflammatory response. They are very useful for inflammatory bowel disease such as proctitis, but like local anaesthetics, they can mask symptoms of otherwise easily treatable perianal conditions. Be wary of using steroids if viral or fungal infection is suspected.

Antibiotics are undoubtedly effective in the short term. A longer-term strategy should be directed at improving local barriers (healthy skin) to infection.

Skin protective pastes such as zinc and castor oil or petroleum jelly can provide protection from moisture, but need to be applied in a very thin layer. Apply the ointment after a wash or the irritants will be trapped on the wrong side of the protective barrier.

Astringents and vasoconstrictors are absorbed across the mucosa and can decrease local inflammation and theoretically stop active bleeding. Adrenaline is available in some haemorrhoidal preparations (suppositories) and zinc oxide is a mild astringent.

Glyceryl trinitrate causes relaxation of the internal anal sphincter (by acting as a nitric oxide donor). Diluted to 0.2%, it can provide relief from fissure in ano.¹ Apply the ointment with a gloved finger (or finger wrapped in plastic wrap) to minimise systemic absorption and headache.

Common conditions

Pruritus ani

The patient and their family should be wormed. The rectum should be kept empty if possible. Food allergy (especially coffee and chocolate) and candidiasis need to be considered. Contact dermatitis or a reaction to bubble baths or soaps may be responsible. Children may sometimes have a painful perianal streptococcal infection (see figure below) as a cause of symptoms. Topical treatments and other strategies such as not using toilet paper can help. Use of a preparation containing local anaesthetic and steroid may help break a vicious cycle of repeated skin trauma from scratching, but repeated requests for prescriptions should prompt referral.

Figure Perianal streptoccocal infection Picture provided by Dr Noel Cranswick, Royal Children's Hospital, Melbourne

Thrombosed external haemorrhoids

Easily recognised as a tense blue perianal lump, a thrombosed external haemorrhoid produces severe pain. The natural history is that of steady deterioration for three days followed by resolution. A skin tag will result. If diagnosed earlier than three days, the natural history can be circumvented by incising or (preferably) excising the haematoma. Expectant symptomatic management with a local anaesthetic is acceptable, but often surprisingly ineffective. A comfortably warm, deep bath does help. Resulting skin tags can make it difficult to keep the perianal skin clean but if the previously mentioned strategies are successful the tags need not be removed.

Fissure in ano

Many will heal with symptomatic treatment alone. A combination of steroid and local anaesthetic will heal the majority of acute fissures. Use psyllium or similar bulk laxative to ensure a soft bulky stool which will dilate the anal canal. Avoid the trauma of toilet paper in favour of a shower after bowel movements. Consider glyceryl trinitrate ointment and referral. If symptoms are severe, suggest that the patient run a warm bath before defecating so that relief will be at hand.

Haemorrhoids

The symptoms of true internal haemorrhoids are often due to their effect on the perianal skin and can be managed by skin care and topical treatments. Bleeding and prolapse will respond to simple surgical measures.

Prolapsed thrombosed internal haemorrhoids

These can often be reduced with gentle sustained pressure after the application of local anaesthetic gel. Natural resolution begins to occur after five days. Ice (and, somewhat paradoxically, warm baths), oral analgesics and topical local anaesthetics may help.

Persistent symptoms

• Many common anal conditions are amenable to simple and effective surgical procedures.
• Remember that both benign and malignant conditions share symptoms that can be masked by topical anal preparations, so there should be a relatively low threshold for referral.

The following statements are either true or false.

1. Prolonged use of topical anaesthetics can cause skin sensitivity.

2. Fissure in ano usually requires surgical closure.

Answers to self-test questions

1. True

2. False