膀胱重量算出ノモグラムを使用した下部尿路閉塞の評価

Abstract

膀胱重量算出ノモグラムの有用性を15例で検討した.ノモグラムは, 横軸に膀胱壁の厚さ(T), 縦軸に膀胱重量(BW)をとり, 一定の膀胱容量における計算上のTとBWのプロットから作成した.各症例の膀胱重量は, まず膀胱内圧を測定し, 最大蓄尿時にエコー測定上のTと生理的食塩水膀胱注入量からノモグラムを用いて推定した.膀胱壁は排尿筋に一致する低エコー領域と, 漿膜下組織および粘膜・粘膜下組織の高エコー領域からなる3層構造として描出されるので, 排尿筋を挟む上下の高エコー領域の幅を計測することにより壁の厚さを求めた.結果として膀胱重量の推定が可能であり, 所要時間は超音波検査後Tの平均値の算出時間およびノモグラムからの膀胱重量の読み取り時間などを合わせて約30秒であった

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.