The purpose of an investigation is to confirm or amend a diagnosis. Care should be taken not to jump to premature conclusions or to proceed to complex and expensive investigations when simple investigations would suffice. Investigations themselves may be associated with complications and should therefore only be carried out when appropriate. If an investigation is associated with a significant complication, these problems should be explained to the patient in the same way that the problems associated with a surgical operation should be explained. The patient should be made aware of the need for the investigation, why this particular investigation needs to be carried out, what information will be obtained from the investigation and how that will affect their management, what complications can occur and, if they do occur, what treatment will be necessary.