The answer
The main differential diagnosis is colitis due to any of a number of causes,
such as ischaemic colitis, infective colitis and colitis due to inflammatory
bowel disease.
What the student may say
The clinical history would raise the possibility of constipation with
overflow diarrhoea, pseudo-obstruction, or a mechanical large bowel obstruction
perhaps due to volvulus or a tumor, however, the plain film shows no evidence
of obstruction or constipation. The oedematous colon goes strongly against the
diasnosis of pseudo-obstruction. I presume the rectum was empty on clinical
examination? The most likely diagnosis based upon the clinical history and the
plain film would be colitis.
The three main types of colitis that should be considered are colitis
associated with inflammatory bowel disease, ischaemic colitis and an infective
colitis.
It would be wise to see if the was a past or family history of inflammatory
bowel disease. Ischaemic colitis may occur on a background of atherosclerosis,
or may be due to cardio-arterial embolistaion, arterio-arterial embolisation,
or may occur consequent to a small vessel occlusion due to vasculitis or
disseminated intravascular coagulation. Infective colitis is seen mainly as a
pseudomembranous colitis due to overgrowth of Clostridium Difficle in ill
patients who have received antibiotics.
I would like to know more about the patients general condition in the
previous few days, and if the patient has received antibiotics or are being
treated with drugs that reduce intestinal blood flow.
Small print
One of the treatments of patients with a subarachnoid haemmorhage is
hypertensive therapy in the form of ino-tropic drugs. The idea is to maximise
the amount of blood flowing to the brain. These drugs reduce intestinal blood
flow.
The pattern of distension in the bowel does not look like a sigmoid
volvulus.
There is no evidence of constipation on the plain abdominal film.
The major cause of abdominal distension in patients being treated for non
abdominal complaints is pseudo-obstruction where the intestine stops working.
This slows the patients recovery and causes diagnostic confusion, with both
abdominal complications of the underlying illness and its treatment and with
pre-existing problems that only come to light during the course of the
non-abdominal illness. What the real problem is, will become obvious with time.
However close attention to basic principles will aid early identification of
more serious problems so that appropriate treatment may be instigated.
