The words "confusable disease" and "associated disease" are always used in connection with another disease, in our situation in connection with BPS.

For BPS, a confusable disease is a disease which may show similar symptoms and/or signs to those of BPS. In general, such a confusable disease needs to be excluded as the main cause of the symptoms and/or signs before a diagnosis of BPS can be made. In practice, the situation may be more complex as the presence of a confusable disease does not necessarily exclude the presence of BPS as well. If both a confusable disease and BPS are present, it is clear that for individual diagnoses of patients and for epidemiological studies, the presence of a confusable disease should not exclude a diagnosis of BPS. For many scientific studies, on the other hand, e.g. for studies on the effect of a particular treatment, only patients with BPS without an additional confusable disease should be accepted as the confusable disease may severely interfere with outcome parameters of such a study.

BPS has several associated diseases. Associated diseases are diseases with a higher prevalence among patients with BPS than in the general population. This does not necessarily imply a causal relationship between BPS and the associated disease. The practical consequence of associated diseases is that medical professionals should know these associations and should have a high index of suspicion for the associated diseases.

• Interstitial cystitis and associated disorders
  by Joop P van de Merwe, M.D.

• Interstitial cystitis and gastrointestinal disorders
  by Joop P van de Merwe, M.D.