Differentials
Anal fissure
SIGNS / SYMPTOMS
Anal fissures are associated with painful bleeding on defecation and possibly a sentinel skin tag (sometimes reported by the patient as a 'painful haemorrhoid'). Fissures are seen as linear tears in the anal mucosae, most commonly in the posterior midline of the anal canal.
INVESTIGATIONS
Physical examination.
Crohn's disease
SIGNS / SYMPTOMS
Crohn's disease affecting the large bowel can present with rectal bleeding and is associated with diarrhoea rather than constipation. Family history of inflammatory bowel disease is often present.
INVESTIGATIONS
Endoscopy findings highly variable, depending on disease activity. Characteristically shows 'skip areas' with areas of disease with intervening areas of normal mucosa. Usually most severe in the cecum and right colon, with rectum often spared.
Ulcerative colitis
SIGNS / SYMPTOMS
Ulcerative colitis commonly presents with rectal bleeding and is associated with diarrhoea rather than constipation. Family history of inflammatory bowel disease is often present.
INVESTIGATIONS
Endoscopy reveals diffuse inflammation and ulceration in cases of acute ulcerative colitis.
Colorectal cancer
SIGNS / SYMPTOMS
History of altered bowel habit (diarrhoea and/or constipation), abdominal pain, weight loss, iron-deficiency anaemia, colonic polyps, and positive family history suggest colorectal cancer.
INVESTIGATIONS
Endoscopy may reveal mass, stricture, and obstruction. Blood tests commonly reveal anaemia.
Anal fistula
SIGNS / SYMPTOMS
Commonly bleeding with a history of a preceding abscess, with continued intermittent bloody/purulent drainage. Visualised as a punctate opening on the anal margin adjacent to the anal canal.
INVESTIGATIONS
Physical examination.
Rectal prolapse
SIGNS / SYMPTOMS
Usually presents as protruding mass per rectum especially with straining. May be associated with mucus or blood-stained discharge, pain, and or faecal incontinence.
INVESTIGATIONS
Physical examination. A defecogram may help distinguish between mucosal prolapse and a full-thickness rectal prolapse. Examination under anaesthesia may be required to confirm and assess severity.
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