Differentials
Irritable bowel syndrome
SIGNS / SYMPTOMS
Clinical diagnosis of irritable bowel syndrome (IBS) is based on the Rome IV Criteria. Recurrent abdominal pain, on average, at least 1 day/week in the last 3 months, associated with two or more of the following criteria (fulfilled for the last 3 months with symptom onset at least 6 months before diagnosis): related to defecation; associated with a change in frequency of stool; associated with a change in appearance of stool.[168]
INVESTIGATIONS
There is no specific diagnostic test for IBS.
Patients who fulfil the clinical criteria for IBS and have no alarm features have a very low probability of organic disease. Colonoscopy or colonic imaging is recommended for patients aged >50 years due to higher pre-test probability of colorectal cancer.[169]
Ulcerative colitis
SIGNS / SYMPTOMS
Compared with colorectal cancer, ulcerative colitis occurs at a slightly younger age (30-40 years).[170]
Patients with inflammatory bowel disease frequently have watery diarrhoea.
Patients with ulcerative colitis are at increased risk of developing colorectal cancer, and should undergo colonoscopic screening and surveillance.[171]
INVESTIGATIONS
Colonoscopy will show rectal involvement, continuous uniform involvement, loss of vascular marking, diffuse erythema, mucosal granularity, normal terminal ileum (or mild 'backwash' ileitis in pancolitis).
Crohn's disease
SIGNS / SYMPTOMS
Compared with colorectal cancer, Crohn's disease occurs at a younger age (20-30 years).[170]
Patients with inflammatory bowel disease frequently have watery diarrhoea.
Patients with Crohn's disease are at increased risk of developing colorectal cancer, and should undergo colonoscopic screening and surveillance.[171]
INVESTIGATIONS
Colonoscopy with intubation of the ileum is the definitive test to diagnose Crohn's disease and will show mucosal inflammation and discrete deep superficial ulcers located transversely and longitudinally, creating a cobblestone appearance. The lesions are discontinuous, with intermittent areas of normal-appearing bowel (skip lesions).
Haemorrhoids
SIGNS / SYMPTOMS
Cause bright red rectal bleeding that is separate from the stool. There is no abdominal discomfort or pain, altered bowel habits, or weight loss.
INVESTIGATIONS
Colonoscopy or colonic imaging is recommended in patients with abdominal symptoms in addition to rectal bleeding and in those aged >50 years. It is also recommended for patients for whom clinic proctological assessment fails to detect an anal source of bleeding.
Anal fissure
SIGNS / SYMPTOMS
Severe pain on defecation. Blood is usual on wiping. There is no abdominal discomfort or pain, altered bowel habits, or weight loss.
INVESTIGATIONS
Colonoscopy or colonic imaging is recommended in patients with abdominal symptoms in addition to rectal bleeding and in those aged >50 years.
Diverticular disease
SIGNS / SYMPTOMS
Diverticular stricture or inflammatory mass may be clinically indistinguishable from colorectal cancer.
INVESTIGATIONS
Colonoscopy is indicated to evaluate stricture, but may be contraindicated in patients with an acute inflammatory condition.
Primary prostate pain syndrome
SIGNS / SYMPTOMS
Typically presents as persistent pelvic pain of at least 3 months’ duration centred around the prostate. Pain may also occur in other pelvic areas outside the prostate including in rectum, perineum, penis, testicles, abdomen, lower back, and/or inguinal region.
Patients may also report associated lower urinary tract signs and symptoms and/or signs and symptoms of sexual dysfunction, such as dysuria, urinary frequency, urinary urgency with/without urge incontinence, poor stream, nocturia, or pain on or after ejaculation.
INVESTIGATIONS
Clinical diagnosis: investigations are used to exclude other causes of pain and to aid phenotyping.
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