Abnormal detrusor function precipitating hydronephrosis identified by extended voiding cystometry.

Extended voiding cystometry was performed to elucidate the true detrusor function in a patient originally misdiagnosed during standard fill cystometry. This methodology allows for observation of an extended period of bladder activity and eliminates the artifacts of classical fill cystometry, which are detrusor instability and noncompliance. A chronically elevated intravesical pressure between contractions (inter-contraction pressure) representing high pressure residual urine, as well as frequent, high amplitude, long duration detrusor contractions during the storage phase and a large post-void residual urine volume were documented. These urodynamic abnormalities are known to precipitate hydroureteronephrosis in the absence of vesicoureteral reflux.