BOF: 3.32
A 63-year-old male presents
with a 6-day history of diarrhoea and lower abdominal pain. He is known to
have COPD and has had several courses of antibiotics recently for what his GP
thought were infective exacerbations.
On examination the patient
looks unwell, he is febrile (temp 39°
C) dehydrated, tachycardic and his blood pressure is low. His abdomen is
distended and tender, no lumps palpable, bowel sounds are heard and not
exaggerated.
Which of the following
investigations would be most appropriate in this patient?
a)
Plain x-ray abdomen
b)
Stool microscopy and culture
c)
CT scan of the abdomen
d)
Colonoscopy
e)
Unprepared flexible sigmoidoscopy
Answer: e)
The history and examination
suggest the patient has an acute inflammatory condition of his bowel. With the
history of antibiotic treatment the likely cause is pseudomembranous colitis
due to Clostridium difficile rather than an infective colitis.
Idiopathic inflammatory bowel disease such as ulcerative colitis is unlikely
as the history is too short. Ischaemic colitis usually has a much more
dramatic onset.
The best way to make a quick
diagnosis would be to perform an unprepared flexible sigmoidoscopy and
directly view the mucosa. As the patient has diarrhoea it is likely that the
distal colon is involved. This should be sufficient to make a diagnosis and
biopsies could be taken to provide histological confirmation.
Colonoscopy would be unwise
in the setting of an acutely inflamed colon, as this would increase the risk
of perforation.
CT scanning would show
inflammation of the colon but the type of colitis would be unclear.
Plain x-ray would be useful
in detecting toxic mega colon and may sometimes show thumb printing in colitis
but these changes are not specific.
Stool microscopy and culture
are unhelpful but toxin assay would point to the diagnosis
Revision Tip
Revise pseudomembranous
colitis KEYS to SUCCESS in Medicine page
257-258
