Urodynamic study and potassium sensitivity test for women with frequency-urgency syndrome and interstitial cystitis

The intravesical potassium chloride (KCl) sensitivity test has been used to detect urothelial leakage in patients with frequency-urgency syndrome and interstitial cystitis (IC). It is unclear whether urodynamic studies can predict a positive KCl test. This study compared the urodynamic results for women with different KCl responses who suffered from frequency-urgency syndrome and IC.

A total of 196 women suffering from frequency, urgency and/or bladder pain were enrolled in this study. These patients underwent a urodynamic study with a concurrent KCl test. The urodynamic results were compared between the patients who had positive and those who had negative KCl tests and between the patients with and without characteristic IC under cystoscopic hydrodilatation.

Among 196 women, 138 (70.4%) had a positive and 58 (29.6%) a negative KCl test. Among the patients with a positive KCl test, 128 underwent cystoscopic hydrodilatation: 44 were proven to have characteristic IC, and 84 were not. Patients with a negative KCl test had a larger residual urine volume and a higher incidence of poor relaxation of the urethral sphincter than those with a positive test. However, patients with a positive KCl test and proven IC did not differ in urodynamic parameters from non-IC patients. The symptom of bladder pain could not predict a positive KCl test nor characteristic IC either.

This study shows that no specific urodynamic parameter or specific symptoms can predict a positive KCl test in patients with frequency-urgency syndrome or IC. Patients with bladder pain at full bladder and a positive KCl test had only a 45.2% chance to have characteristic IC.