BERKELEY, CA (UroToday.com) - The localization of the urge to void seems to involve a wider area in patients with PBS than in those with overactive bladder (OAB), stress incontinence (SI), and asymptomatic controls. Fitzgerald, Kenton, and Brubaker report that 53% of 30 PBS patients localized their urinary urgency/discomfort to both suprapubic and vulvar/urethral locations. Some patients with PBS also localized their urinary discomfort to other body sites including low back, upper and lateral buttocks, lower abdomen, and upper thighs.

These findings contrast with those of 25 overactive bladder patients, 15 stress incontinence patients, and 15 asymptomatic controls. Eighty per cent of OAB patients and all SI and asymptomatic controls studied localized their urge to void in the suprapubic area only. The authors postulate that in PBS and a minority of OAB patients where bladder hyperalgesia is present; there are expanded dermatomes of referral of bladder sensation. This phenomenon has been documented in patients with irritable bowel syndrome, another visceral pain syndrome. A second explanation put forward is that when bladder hyperalgesia is present, concomitant urethral hyperalgesia is also present and urgency is experienced in the vulvar/urethral region.

Another possibility may be that in patients with PBS, several pain generators outside the bladder may be important contributors to the pain/urgency experience. It is also conceivable that the different localizations may arise because patients with PBS may map the location of their sensation of urinary urgency, while the other groups studied mapped the location of their normal urge to urinate.

The authors caution that while the International Continence Society definition of painful bladder syndrome places emphasis on the suprapubic location of bladder pain, this may be misleading in some patients who may experience bladder pain in other sites including the low back, upper thighs, or perineum. One wonders, however, how one can clinically make a diagnosis of painful bladder syndrome in the absence of the patient's perception of some degree of suprapubic or bladder pain.

Neurourology and Urodynamics 2005 November; 24:633-637