Differentials
Diverticular disease
SIGNS / SYMPTOMS
Abdominal cramping, constipation, pain, and diarrhoea are characteristic.
INVESTIGATIONS
Computed tomography scan identifies colonic diverticula, pericolic fat stranding, thickened bowel wall, soft tissue swelling, and abscesses in diverticular disease.
Once diverticulitis has subsided, colonoscopy may be performed to determine the extent of disease and to aid in differentiation.
Colorectal cancer
SIGNS / SYMPTOMS
A change in bowel habits, tenesmus, and weight loss are more common in patients with colon cancer, and are sometimes associated with the presence of an abdominal mass.
INVESTIGATIONS
Colonoscopy identifies mass lesions, which can then be biopsied.
Gastrointestinal stromal tumours and leiomyomas
SIGNS / SYMPTOMS
These tumours occur mainly in the upper gastrointestinal tract and present with dysphagia, gastrointestinal haemorrhage, or metastases (mainly in the liver).
INVESTIGATIONS
Oesophago-gastro-duodenoscopy allows identification and biopsy in most patients.
Haemorrhoids
SIGNS / SYMPTOMS
Pruritus ani, haemorrhoid lesions with no haematochezia or melaena on physical examination.
INVESTIGATIONS
Proctoscopy demonstrates haemorrhoid lesions.
Crohn's disease
SIGNS / SYMPTOMS
Abdominal pain, weight loss, fever, aphthous ulcers, change of bowel habit, and urgency are characteristic.
INVESTIGATIONS
Colonoscopy identifies patchy inflammation and ulcerations.
Ulcerative colitis
SIGNS / SYMPTOMS
Abdominal pain, weight loss, fever, extra-intestinal manifestations, change of bowel habit, and urgency are characteristic.
INVESTIGATIONS
Colonoscopy demonstrates continuous erythema, mucosal friability and ulceration, and pseudopolyps in the colon and rectum.
Ischaemic bowel disease
SIGNS / SYMPTOMS
Sudden onset abdominal pain out of proportion to physical signs, a change in bowel habit, nausea, vomiting, and fever.
INVESTIGATIONS
A high WBC count and low serum bicarbonate level aid in identifying ischaemic bowel disease.
Colonoscopy identifies petechial haemorrhages with pale, swollen mucosal areas in early ischaemia. Severe ischaemia is associated with grey, cyanotic, or black mucosa.
Meckel's diverticulum
SIGNS / SYMPTOMS
Abdominal pain, bloating, and symptoms of intestinal obstruction.
INVESTIGATIONS
A technetium Tc-99m pertechnetate scan is the preferred investigation.
Infectious colitis
SIGNS / SYMPTOMS
Abdominal pain, fever, vomiting, nausea, and diarrhoea are characteristic.
INVESTIGATIONS
On colonoscopy, infectious colitis may display pseudomembranous tissue.
Cultures for Clostridium difficile are recommended in addition to conventional pathogens such as salmonella and campylobacter.
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