Perianal conditions - Clinical Tree

Essentials

1
Anal pain, bleeding and masses are common symptoms in many different types of anorectal pathology. A careful history and anorectal examination are important in making the correct diagnosis.
2
Increasing fibre intake and reducing constipation are effective initial treatments for mild, uncomplicated haemorrhoidal disease and perianal fissures.
3
Anorectal abscesses require incision and drainage. In some cases, this can be done safely in the emergency department, but all supralevator, intersphincteric and ischiorectal abscesses require formal surgical exploration and drainage in theatre.
4
Incision and drainage of cutaneous abscesses is not associated with bacteraemia in immunocompetent, afebrile adults, so routine antibiotic cover is not required.
5
Irreducible haemorrhoids require urgent reduction and surgery.

Anorectal abscesses and fistulae

Introduction

Anorectal abscesses and fistulae are the acute and chronic phases of the same disease. An infection in the anal gland caused by occlusion of the crypt is the usual source. Anorectal abscesses are twice as common in men as in women and are most common between 20 and 40 years of age. Associated factors may include inflammatory bowel disease, infection, trauma, surgery, malignancy, radiation and immunosuppression. Fistula formation following the first presentation of an anorectal abscess occurs overall in about 20% of cases, with higher rates in patients with Crohn disease. Fistulous tracts may be multiple and be intimately related to the sphincters essential for continence. Treatment of anorectal fistulae is complex and the domain of colorectal surgeons.

Perianal pain is the most common symptom. Swelling and fever may also be present. Examination reveals a tender, erythematous, fluctuant mass in the anorectal region.

One commonly used classification system ( Fig. 7.14.1 ) is according to the four potential anorectal spaces they may occupy.

Fig 7.14.1, Anatomic locations of anorectal abscesses.

Perianal abscess

Perianal abscess presents as a painful lump around the anal verge, usually lateral and posterior to the anus. It may result from an infected anal gland or, more rarely, is a presentation of Crohn disease. Systemic symptoms are uncommon. On examination, most will be pointing, with an indurated red area that may be fluctuant. Such abscesses may be suitable for incision and drainage in the emergency department (ED).

Ischiorectal abscess

Ischiorectal (or perirectal) abscesses tend to be larger yet may present with less dramatic cutaneous findings because of the compressibility of ischiorectal fat. Patients may be febrile and systemically unwell. The area of induration is likely to be large and more lateral than a simple perianal abscess. Pointing may not occur until late and the initial assessment may seem more like buttock cellulitis.

Intersphincteric abscess

Intersphincteric or submucous abscesses are within the anal canal, between the internal and external sphincter. These abscesses may be associated with severe pain and with urinary symptoms although no external swelling may be visible. They point within the anal canal and may rupture spontaneously.

Supralevator abscess

Supralevator abscesses arise above the levator ani. They can be considered to be pelvic abscesses and are often secondary to intra-abdominal conditions such as diverticular disease or Crohn disease. A supralevator abscess may present as pyrexia of unknown origin. The patient may present with pain on defecation and altered bowel habit. Inspection of the perineum may be normal but rectal examination will reveal a firm, spongy, tender mass.

Treatment

The treatment of all anorectal abscesses is incision and drainage. There is no role for antibiotic treatment alone. Small perianal abscesses can be considered for drainage in the ED using local anaesthesia. Radial, curvilinear and/or a cruciate incision may be used, although each has different risks and benefits in regard to further fistula surgery and anal sphincter damage. All other larger and more complicated anorectal abscesses are best treated under general anaesthesia by a surgeon with colorectal expertise in order to minimize the risk of complications including fistula formation and damage to the anal sphincter. Diagnosis of fistulous disease is suspected on a history of recurrent perianal suppuration and is confirmed by the delineation of fistulous tracks during surgery under anaesthesia. In carefully selected patients, immediate management of the fistula may decrease recurrence or persistence of abscess without an increase in incontinence. The drained wound should be kept open long enough for the abscess to heal from below and may require placement of a formal drain. Aggressive probing of the cavity should be avoided, as it can lead to iatrogenic fistulae. Regular sitz baths, review and dressing changes should continue until healing is confirmed. Antibiotics are ineffective and are indicated only as an adjunct in patients with valvular or rheumatic heart disease, diabetes, immunosuppression, extensive cellulitis or a prosthetic device.

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