IMPAIRED BLADDER CONTRACTILITY IN ASSOCIATION WITH DETRUSOR INSTABILITY - UNDERESTIMATED OCCURRENCE IN BENIGN PROSTATIC HYPERPLASIA

The hyperactive bladder does not always completely empty. The aim of this study was to determine the frequency of detrusor instability and impaired contractility in 45 patients with benign prostatic hyperplasia. The evaluation consisted of uroflowmetry, residual urine determination, cystometrogram (CMG), and micturition study with stop-flow technique. Detrusor instability is diagnosed urodynamically with the appearance of abnormal contractions either on medium filling CMG and/or on a provocative rapid injection CMG. Impaired bladder contractility was diagnosed by the presence of significant residual urine (greater-than-or-equal-to 50% of capacity) and unsustained bladder contraction with no or little detrusor reserve power. Urodynamic evaluation showed that 21 out of 45 patients had detrusor instability. Seven of these patients showed also impaired contractility. The mean residual urine was 380 ml in this subgroup. On micturition studies five of these patients showed low pressure, low uroflow pattern. Stop-flow technique revealed absence of detrusor reserve power in five patients, while two patients showed little detrusor reserve power. Out of the 24 patients with stable bladders, four showed impaired contractility. Indeed, detrusor instability is not associated exclusively with low residual urine values. The importance of recognizing detrusor instability in combination with poor contractility in patients with benign prostatic hyperplasia is that one can anticipate incomplete bladder emptying even after protstate surgery and consider other forms of therapy. Our approach to this specific problem is presented.