Thursday, 4 September 2008

A Minor Gripe - Work Up Of Constipation

Dear Bloggers

Today I would like to have a minor gripe. My gripe is about the overuse of abdominal X-rays to rule in / rule out constipation.

Patients with constipation may present with various symptoms including:
  • Nausea
  • Vomiting
  • Anorexia
  • Difficulty passing stool (straining)
  • Passage of hard stools
  • Abdominal pain
A rectal examination provides far more information than an abdominal X-ray when working up a patient with constipation. Feeling for hard stool, determining if there is occult blood, malaena or frank hemorrhage and determining if there is malignancy e.g. colorectal / prostate cancer is all possible and essential, something that a plain X-ray cannot do.

To perform an abdominal X-ray in order to avoid the rectal exam is in my opinion a neglection of duty to the patient. Patients may indeed have a full colon with stool and an X-ray may reveal that constipation is present, but it does not provide the mechanism which caused the constipation. For example, is the constipation due to sluggish bowel movement or a rectal cancer!?? A plain film will not always show you the cancer hiding in the rectum --- only the examining finger can do that or more advanced radiological studies.

In this technological age, aren't we forgetting our basic examination skills that have been tried and tested by the ingenious physicians of the past only to be replaced by fine CT pictures that cannot always provide the diagnosis that we are seeking. Without the background of thorough physical examination skills, soley relying on a machine to make a diagnosis is like building a brick house on sand --- it is destined to sink when we need shelter from the storm. We need a good foundation on which to build and that foundation is the physical examination.

Performing a rectal examination is free and does not cause radiation exposure whereas an X-ray does cost money (albeit pennies / yen) and there is significant radiation exposure. This latter point is something that many physicians forget. Never do harm to your patients and do not expose them to unnecessary procedures which might be harmful (immediately or long term) when another method might provide the same or better information with less harm.

Hence, when it comes to constipation please remember to do the rectal examination. If you are concerned about bowel obstruction then that would be an indication for an AXR but it cannot really be justified to take a plain film to rule out / rule in constipation when your finger can give the same information.

If you want to investigate further (after a rectal exam), then I would suggest utilising an ultrasound scan which is non-invasive and provides no radiation exposure.

X-rays and CT scans should be reserved for those patients in whom the diagnosis is unclear after the basic physical examination and ultrasound and in whom you want to rule out serious pathology. They should not be utilised as a first measure unless there is evidence of an acute pathology e.g. acute surgical abdomen, and by which other tests cannot provide the diagnosis. Remember that radiation from CT scans increases the risk of cancer -- please see a previous blog article from 2007 which explains this in more detail on the following link.

Please Consider......

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