We report a case of bladder outflow obstruction presenting with upper tract dilatation mistaken initially as pelviureteric junction (PUJ) obstruction. The lower tract obstruction ought to be dealt with first before upper tract obstruction is assessed because the renal pelvic pressure is significantly affected by vesical filling and high bladder pressure.
The uroflow and pressure-flow data of 67 men aged 65 years or more were compared. At best, the uroflow study applying the Liverpool nomogram (25th percentile) and Bristol nomogram (OSD) diagnosed bladder outlet obstruction with sensitivity of 62.5% and 62.5% and specificity of 48.8% and 74.4% respectively. Using the 50th percentile of the Liverpool nomogram as the cut-off resulted in a negative predictive value of 100.0% allowing about 10% of men to have this diagnosis ruled out. We conclude that the uroflow study is inaccurate in diagnosing bladder outlet obstruction in elderly men. However, it can be used to rule out this condition in the small subset of men with maximum flow rates above the 50th percentile of the Liverpool nomogram.