Case

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.

Introduction

Perianal pain may be a mild discomfort, an acute severe pain, or a chronic debilitating symptom. The nature of the pain and any associated symptoms will provide important clues to the cause. Important points are the severity of the pain, the duration of the pain, the relationship of pain to defecation, and associated bowel symptoms such as rectal bleeding, prolapse at the anus, or discharge of pus.

The causes of perianal pain are listed in Box 12.1.

History

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).

Examination

Fissure-in-Ano

Pathology

The acute fissure is a superficial split with soft edges.

A chronic fissure evolves through several phases:

• superficial—longitudinal muscle fibres of musculus submucosae ani may be seen in the base;

• deeper fissure—the edges may be indurated; transverse fibres of internal sphincter are seen;

• advanced fissure—edges are indurated and may be undermined; a skin tag (sentinel pile) develops at the lower edge; a fibroepithelial polyp (hypertrophied anal papilla) may form at the upper end of the fissure at the dentate line (see Fig 12.1);

Figure 12.1 Chronic anal fissure. Note the deep chronic posterior fissure with skin tag below and fibroepithelial polyp above.

Finally, an abscess may form in the submucosal plane or in the skin tag leading to a superficial fistula, or between the internal and external sphincters (intersphincteric).

Secondary fissures may be broad or long. If a fissure extends into the upper anal canal above the dentate line, it is usually a secondary fissure. These are sometimes called anal ulcers.