A prospective controlled quantitative study of ultrastructural changes in the underactive detrusor.

Purpose: We quantify and compare ultrastructural changes seen at high power on electron microscopic examination of detrusor biopsies from underactive and control bladders.
Materials and Methods: The detrusor underactivity group consisted of 14 patients (mean age 64.0 years) with post-micturition residuals greater than 300 ml., impaired contractility and no obstruction on urodynamics. A total of 17 patients who voided normally voiders with residual volume less than 50 ml. served as the control group. Bladder biopsies were obtained endoscopically using cold cup technique and processed using standard methods. All specimens were randomized and studied at high power (x12,000 to x24,000) by an examiner who was blinded to the groups. All complete cells within each random grid field were counted up to a total of 500. The number of disrupted cells per 500 cells was noted.
Results: Disruptive cell profiles were found in all biopsies. Median cell count was 20 cells/500 in 14 controls and 96.5 cells/500 in the underactive detrusor group (p <0.001). The number of disruptive cell profiles did not correlate with age in the control group (r = 0.34, p = 0.18).
Conclusions: There were distinct morphological changes in the detrusor associated with bladder dysfunction with approximately 4 times more disruptive cells in patients with an underactive bladder. However, there was no correlation between age and number of disruptive cells, suggesting that this is not a process of aging per se. Ultrastructure studies may have a role as an adjunct to urodynamics in the diagnosis of bladder dysfunction.