Perianal pain

Published on 13/02/2015 by admin

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12 Perianal pain


Mrs JS is a 35-year-old woman who presents with severe anal pain on defecation. The pain had worsened over the previous 6 months. On further questioning she admitted to straining at stool, and the stool was sometimes hard and pellet-like. Her pain occurred spontaneously when sitting but was greatly exacerbated while passing a stool and lasted up to an hour. As a result, she was reluctant to pass stool and often held back passing a motion for 2 or 3 days. She noted bright blood on the toilet paper intermittently. She had also noted a small swelling at the anus but was not aware of any prolapse during defecation. She had a background history of two normal vaginal deliveries, without a perineal tear or episiotomy. She was otherwise fit and healthy. Abdominal examination was normal. On anal examination there was a fissure posteriorly in the midline with a sentinel tag. On gentle digital examination she was exquisitely tender posteriorly just within the anal verge, and no further internal examination or proctoscopy was carried out. There was no perianal inflammation, swelling or tenderness.

Diagnosis: The history of severe acute anal pain usually suggests an anal fissure or perianal abscess (or other abscess, such as intersphincteric or ischiorectal). The finding of localised tenderness in the posterior midline within the anal canal is almost certainly due to a fissure. Haemorrhoids do not cause severe pain unless the haemorrhoids are thrombosed, in which case there are obvious prolapsed tender haemorrhoids on anorectal examination. Although haemorrhoids are more common than anal fissures overall, prolapsing haemorrhoids that are not acutely thrombosed cause slight discomfort only; the most common cause of severe pain is anal fissure.

Management and progress: First-line management is with dietary changes. The patient was commenced on a high fibre diet (of at least 30 g per day), supplemented with additional fibre such as psyllium (Metamucil™), with at least 1.5 L of water, to soften her stools. She was treated with glyceryl trinitrate (GTN) 0.2% cream (Rectogesic™) placed into the lower anal canal twice daily. She developed a troublesome headache after application of the cream. She was instructed to then reduce the amount used to the point where headaches do not occur, to continue with that dose for 2 or 3 days and then gradually increase to the recommended dose (the body adjusts to the lower dose, and the higher dose is subsequently tolerated, by the process of tachyphylaxis).

Her pain improved considerably, but she returned 6 weeks later complaining of a recurrence of severe pain. She had successfully softened her stool and had complied with use of the GTN for 4 weeks to allow the fissure time to granulate.

She was then progressed to the next line of treatment, which is injection of Botox®. This was carried out in hospital under sedation. A full digital examination and flexible sigmoidoscopy was also carried out to exclude other causes of pain and bleeding, and at the examination there were no signs of proctitis or other mucosal pathology, and no intersphincteric or other perianal sepsis.

The fissure healed and her symptoms resolved. However she again returned after 3 months with a recurrent fissure, producing sufficient pain to cause her to miss days off work. She was advised to undergo lateral sphincterotomy, after providing clear information about the small risk of permanent faecal incontinence (usually minor). After undergoing anal manometry and endoanal ultrasound to confirm that anal sphincter function had not been affected by her vaginal deliveries (and hence place her at increased risk of incontinence after sphincterotomy), she underwent sphincterotomy under general anaesthetic. The fissure healed fully, with complete resolution of pain.


A patient presenting with severe unrelenting pain over recent hours to days, not related to defecation, is likely to have either perianal sepsis or thrombosed haemorrhoids. These patients are usually totally distracted from other activities by the pain. While thrombosed haemorrhoids cause severe, acute pain, non-thrombosed haemorrhoids are usually not associated with pain although there can be discomfort during defecation if the haemorrhoids prolapse.

Typically the pain from an acute anal fissure is severe and is precipitated by defecation; it may take minutes to hours to gradually settle. The pain associated with pruritus ani is annoying but not severe, and is usually associated with the presence of faecal soiling over a raw area.

The pain of anal fistula tends to be mild and associated symptoms are perianal discharge or bleeding. The pain of proctalgia fugax is very typical: sudden onset of a severe, dull rectal ache, often waking the patient from sleep, sometimes causing a desire to defecate, and lasting 15–20 minutes. There may be long periods without any pain. There are a number of chronic perianal pain syndromes associated with a vague dull ache.

The presence of associated bowel symptoms or systemic symptoms may clearly point to the diagnosis. The patient should be asked about rectal bleeding. There may be minor perianal bleeding with anal fissure, usually apparent on the toilet paper after defecation or occasionally on the surface of the stool. With internal haemorrhoids, bleeding can be a more prominent feature than pain; the bleeding tends to be related to defecation and is most commonly noted on the toilet paper or in the toilet bowl. Pruritus ani can be associated with minor bleeding associated with wiping the perianal region after defecation. Perianal abscess is not usually associated with bleeding unless the abscess has discharged spontaneously or has been drained. There may be a minor degree of perianal bleeding with anal fistula. There should not be significant rectal bleeding with any of the chronic pain syndromes or with proctalgia fugax.

Symptoms of constipation are commonly associated with a number of painful perianal conditions (Ch 11). In some cases the constipation leads to the condition, such as fissures or haemorrhoids, but in other cases of anal fissures or thrombosed haemorrhoids the constipation may be caused by the patient’s reluctance to defecate because it induces or exacerbates pain. The conditions causing perianal pain should not themselves be associated with diarrhoea. Therefore, the presence of diarrhoea suggests another disease process (e.g. Crohn’s disease).



While the history will commonly give vital clues as to the cause of the perianal pain, local examination will usually confirm the diagnosis. The examination clearly needs to be focused in the perianal region. A general abdominal examination, however, is essential to detect inflammatory or neoplastic conditions associated with the pain.

The easiest and most comfortable position for inspection is with the patient in the left lateral position with the hips and knees flexed. The buttocks are parted with gentle pressure from the palm of the hand so that the perianal skin can be closely examined. Red excoriated skin suggests that the pain is due to pruritus ani. The presence of a sinus means an anal fistula should be sought. The presence of a spot of pus or blood in the perianal region can point to the external opening of a fistula. A perianal abscess can be associated with a perianal swelling and redness of the overlying skin, depending upon the proximity of the abscess to the external skin.

There may be irregular soft tags of skin, which are asymptomatic, but most commonly associated with a fissure or haemorrhoids. The presence of a small, tense, often bluish swelling just beyond the anal verge is suggestive of a thrombosed external haemorrhoid. An anal fissure is commonly not obvious on external examination and is often very tender, requiring a particular approach in the examination (see ‘Fissure-in-ano’ below). A thrombosed internal haemorrhoid that has prolapsed may be evident at the anal verge as an oedematous 1–2 cm swelling.

Internal haemorrhoids are usually not apparent on external examination. The chronic pain syndromes are not associated with perianal stigmata on inspection.


The features to be sought on palpation are:

A perianal abscess presenting as a perianal lump with associated overlying erythema will always be focally extremely tender. Focal tenderness to palpation is also present with thrombosed internal as well as external haemorrhoids. Severe pain without focal external tenderness is due to either an anal fissure or an intersphincteric abscess (see below).

The patient with an anal fissure will usually not tolerate perianal examination because of the pain. Do not part the buttocks vigorously, and insert the finger very gently (see below). The perianal regions should be gently palpated looking for a subcutaneous or submucosal cord leading from the opening of an anal fistula. This cord should be followed internally and its position in relation to the anal sphincter noted. A prolapsed thrombosed internal haemorrhoid can be distinguished from a thrombosed external haemorrhoid by a cord extending inside the anus to the upper part of the internal haemorrhoid.

Deeper rectal examination may demonstrate focal tenderness associated with abscess formation inside the anus in the intersphincteric space (between internal and external sphincter) or laterally in the ischiorectal fossa. If the cause of the perineal pain is not clear at this stage, gently rocking the coccyx with posterior pressure may elicit sharp pain suggesting the diagnosis of coccygodynia. None of the conditions that cause chronic perianal pain are associated with a palpable abnormality, except the descending perineum syndrome in which the pelvic floor drops down from its usual position.

If an adequate rectal examination is not possible because of perianal pain, it may be necessary to perform this examination under anaesthesia. This examination should be performed by an experienced person capable of dealing with any perianal pathology found on examination.


Proctoscopy will be possible in an office setting for most patients (Ch 22). It will not be possible in patients with an anal fissure, anal abscess or thrombosed haemorrhoids. Proctoscopy will allow a diagnosis of internal haemorrhoids, which will become more prominent or evident as the proctoscope is withdrawn.


Clinical features



Recent studies have found that the substance mediating internal sphincter function is nitric oxide. If a nitric oxide donor, such as 0.2% glyceryl trinitrate cream is applied to the anal mucosa, this produces rapid internal sphincter relaxation, with improved blood flow in the mucosa and resultant healing of a high proportion of chronic fissures. Treatment should continue for at least 4 weeks to allow the fissure to granulate. Glyceryl trinitrate is associated with headaches in about 25% of patients, but these are usually mild and will usually disappear if the dose is reduced. Calcium channel blockers such as diltazem and nifedipine cause smooth muscle relaxation by inhibiting calcium ion channels in smooth muscle, thereby causing sphincter relaxation. Topical diltazem 2% is as effective as 0.2% glyceryl trinitrate and causes fewer headaches; the main side effect is pruritus ani. Healing rates with topical treatments are about 60% in the short term and recurrences occur. If the fissure fails to heal with topical treatment, inactivated botulinum toxin (Botox™) is injected into the sphincter. This paralyses the muscle for about 3 months and allows a further proportion of fissures to heal; about 10% of patients will develop transient incontinence, which settles once the effect of the Botox wears off after 3 months. There is no evidence that other topical agents, including steroids or local anaesthetics, have any effect on fissure healing or pain, and these should be avoided since allergy to local anaesthetics may occur. Use of an anal dilator is an outdated treatment and should be avoided, since it is very painful to use and may damage the sphincter.