Changes in bladder volumes with repetition of water cystometry

Fifty-six patients were investigated by repetitive cystometry in the supine or sitting position. The incidence of detrusor hyperreflexia and the circumstances under which it was found did not differ from previous studies. The cystometry data concerning volumes showed a remarkable degree of variability. Values for first sensation and maximal capacity could vary more than 500%. An increment from the first cystometry to the fourth was consistently found. The increments were most pronounced when cystometry with fast filling followed cystometry with medium filling regardless of the patient's position. The major factor in the changes is considered to be the patient's adaptation to the investigational situation. This finding might have major significance in the evaluation of drug studies where repeated cystometries with different time intervals are used.