[The evaluation of bladder outlet obstruction using the bladder weight calculation nomogram].

The ultrasound estimated bladder weight (UEBW) of 15 patients (13 male, 2 female; mean age 64.7 years) who underwent pressure flow study (PFS) were evaluated using the nomogram. In the nomogram, thickness of bladder wall (T) and bladder weight (BW) were plotted on the horizontal axis and on the vertical axis, respectively. BW points calculated from various values of T by the formula were plotted on the volume-fixed bladder capacity curve. BW of each case was estimated by the nomogram from echo-measured T at maximum bladder filling and injected volume (V) into the bladder. Bladder outlet obstruction (BOO): was evaluated from obtained results, and compared with the results of PFS. The features of the distribution on Schafer's nomogram were also investigated. It was possible to estimate BW immediately after ultrasonic examination. BW was under 35 g in one patient, and over 35 g in 14 patients. Obstruction grade on the Schafer's nomogram ranged from III to VI. BOO could be evaluated quantitatively with little invasion even in patients who could not undergo PFS for urinary retention and urge incontinence. In conclusion, the bladder weight calculation nomogram immediately showed the BOO information of the patient with neither invasive technique, complicated calculation, electronic calculator nor expansive computer. This nomogram may make a breakthrough for utilizing UEBW.