With common and overlapping symptoms and subjective patient reporting, interstitial cystitis/painful bladder syndrome (IC/PBS) and bladder oversensitivity can be difficult to distinguish, making diagnosis and treatment recommendations tricky. To better differentiate between IC/PBS and bladder oversensitivity in women, Dr Yuh-Chen Kuo, from the department of urology at Taipei City Hospital in Taiwan, and Dr Hann-Chorng Kuo, from the department of urology at Buddhist Tzu Chi General Hospital in Taiwan, investigated possible factors that could be used to help in the diagnosis.
Using video-urodynamic study results in women with lower urinary tract symptoms, Kuo and Kuo identified women with increased bladder sensation. They then performed potassium chloride(Drug information on potassium chloride) (KCl) tests, during which patients graded the degree of pain or urgency during infusion of KCl solution. A 10-point visual analogue scale was used to measure the pain while an urgency severity score was used to grade the severity of the sensation (a score of 1 or greater was also considered a positive response).
In comparison to control participants, Kuo and Kuo found that patients with bladder oversensitivity and patients with IC/PBS had significantly lower cystometric bladder capacity. In addition, they found that frequency and bladder pain symptoms were more common among patients with IC/PBS than among patients with bladder oversensitivity or control subjects.
Kuo and Kuo further noted that storage symptoms and pain had a 45.3% positive predictive value for IC/PBS. In addition, the positive predictive value for IC/PBS increased to 65% when cystometric bladder capacity size of less than 350 ml was added to the criteria. The researchers were able to identify 100% patients with IC/PBS when they included storage symptoms and pain, a cystometric bladder capacity ≤350 ml, and a positive KCl test with a visual analogue pain scale score of at least 2. Indeed, all of the women who had those risk factors showed clinical signs of IC/PBS when they underwent cystoscopic hydrodistention.
While the National Institute of Diabetes and Digestive and Kidney Diseases notes diagnosis should be should be based on the presence of positive predictive factors and characteristic cystoscopic findings, recent studies have suggested symptoms alone should lead to a positive diagnosis. This study adds to that literature, noting that patients who report frequency, urgency, or pain symptoms refractory to medical treatment should be treated for IC/PBS without undergoing a cystoscopic hydrodistention procedure.