GPs Dr Keith Hopcroft and Dr Vincent Forte continue their series on making sense of common but often tricky symptoms
Anorectal pain is usually severe and distressing. Reflex sphincteric spasm makes adequate examination difficult, and is also often followed by constipation. Fortunately, if this renders a rectal exam impossible, a visual inspection can often yield the diagnosis.
Differential diagnosis
Common
• Anal fissure
• Thrombosed haemorrhoids/perianal haematoma
• Perianal abscess
• Proctalgia fugax
• Anorectal malignancy.
Occasional
• Crohn's disease
• Coccydynia
• Descending perineum syndrome
• Prostatitis
• Ovarian cyst or tumour.
Rare
• Anal tuberculosis
• Cauda equina lesion
• Endometriosis
• Trauma
• Presacral tumours
Possible investigations
Likely
None.
Possible
• FBC/ESR/CRP: white cells may be raised in abscess and Crohn's disease. ESR/CRP raised in these and carcinoma.
• Proctoscopy: valuable if pain allows.
A specialist might also biopsy.
Rare
• Urinalysis: pus cells and blood may be present in prostatitis or invasive bladder tumour.
• Ultrasound, barium enema or other imaging: Ultrasound of pelvis if pelvic examination reveals a mass. Barium enema may be necessary to assess possible bowel involvement.
Top tips
• If the patient uses dramatic language to describe fleeting pain, is otherwise well and there are no obvious abnormalities on examination, the diagnosis is likely to be proctalgia fugax.
• Examine the patient – most causes can be diagnosed by simple inspection.
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• Provide symptomatic relief, but don't forget to to deal with any underlying causes – especially constipation.
• Don't forget to ask about thirst and urinary frequency: recurrent abscesses may be the first presentation of diabetes.
Red flags
• Preceding weight loss or change in bowel habit should prompt a full urgent assessment with carcinoma and inflammatory bowel disease in mind.
• Some perianal abscesses do not result in external swelling. If a rectal exam is too painful, consider this possibility.
• In florid or recurrent perianal problems, think of Crohn's disease as a possible cause.
• Remember rarer causes in intractable, constant pain in a patient with no obvious signs on a rectal exam.
Dr Keith Hopcroft is a GP in Basildon, Essex
Dr Vincent Forte is a GP in Gorleston, Norfolk
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Quick sorter anorectal pain Anal fissure is a common cause of anorectal pain Anal fissure
