There is confusion surrounding the taxonomy of interstitial cystitis (IC) and its related symptom syndromes, painful bladder syndrome (PBS), bladder pain syndrome (BPS) and overactive bladder (OAB) syndrome.
IC is a disease name long used in medical and consumer societies, but it lacks clear definition. PBS is defined by the International Continence Society (ICS) as “suprapubic pain related to bladder filling, accompanied by other symptoms, such as increased daytime and night-time frequency, in the absence of proven urinary infection or other obvious pathology”, PBS[4, 5] and BPS definitions by other societies all share two requirements: symptoms including pain and lack of identifiable diseases explaining the symptoms. Chimeric terms combining IC and syndromes, IC/PBS (IC/BPS), apparently indicate conditions presenting the symptom complex in the absence of obvious diseases with the possible presence of IC. However, these terms are used interchangeably. In addition, PBS and BPS contain “pain”, creating a misunderstanding that the patient must complain of pain, although a substantial proportion of patients do not. Complaints commonly heard are not directly linked to pain; that is, incessant need to void due to discomfort, loss of normal urinary sensation and an irritable sensation with only little urine in the bladder. These symptoms suggest increased sensation of the bladder or urothelium, a highly sensitive sensory tissue, and an adequate term for such a condition is lacking.
I should therefore like to propose hypersensitive bladder (HSB) (although “hypersensitive” can be replaced by other words implying increased sensation). HSB syndrome is a condition with HSB symptoms with no obvious diseases. HSB symptoms are defined as “increased bladder sensation, usually associated with urinary frequency and nocturia, with or without bladder pain”. They are similar to OAB symptoms; urinary urgency, usually associated with urinary frequency and nocturia, with or without urgency incontinence. Increased bladder sensation is described as “early and persistent desire to void”. IC is defined as a disease requiring: (i) HSB symptoms; (ii) no obvious diseases; and (iii) bladder pathology, such as Hunner's ulcer or mucosal bleeding after overdistension (Fig. 1a). Symptoms of OAB and HSB substantially overlap, whereas OAB with leakage and HSB with pain are readily separated. The compelling need to void in OAB is characterized by the sudden onset and/or fear of leakage, whereas that in HSB is of a persistent unpleasant sensation and/or fear of pain. IC is a representative disease causing HSB symptoms, most typically with pain, but might be painless and indistinguishable from OAB (Fig. 1b).
With these definitions, the following make sense: (i) a woman complaining of HSB symptoms proved to have carcinoma in situ of the bladder; (ii) a woman with HSB symptoms was diagnosed as HSB because no obvious diseases were apparent, but now she is diagnosed with IC based on cystoscopic abnormality; and (iii) a man with HSB showed no definite findings for IC at hydrodistension, so he remained as HSB.
Introducing HSB, the counter concept of OAB, into bladder dysfunction taxonomy will clarify the current confusion surrounding IC.