Effect of the abnormal bladder when full on upper tract drainage using a combined cystometrogram-(99m)Tc-mercapto-acetyltriglycine renogram: a prospective study.
OBJECTIVE
To examine the relevance of bladder volume in patients with chronic hydronephrosis and abnormal bladder function who lose renal function even though the bladder or reservoir pressure is normal (<40 cmH(2)0).


METHODS
In all, 20 patients (16 male; age range 17-67 years) were studied prospectively; 12 had a reconstructed bladder. All had progressive loss of renal function with a glomerular filtration rate (GFR) of >15 mL/min. The study was in three parts: a baseline (99m)Tc-mercapto-acetyltriglycine (MAG3) scan was performed with an empty bladder, then a combined full bladder cystometrogram (CMG) with (99m)Tc-MAG3 study was done supine, and finally repeated in the sitting position. The pressure and volume changes together with the (99m)Tc-MAG3 scintigraphic variables with and without a full bladder were compared.


RESULTS
Of the 17 patients with normotensive bladders, 13 (77%) had functional obstruction of the kidneys with a full bladder. In seven this was threshold dependent and occurred at a total mean (range) bladder volume of 348 (135-720) mL for both positions. In the other six patients there was minimal drainage of isotope from the kidneys even with the bladder empty. When the sitting position was compared with supine, gravity was more important for upper tract drainage in the reconstructed bladders. In five patients the detrusor pressure at which drainage began was close to zero.


CONCLUSIONS
In 13 of 17 patients (77%) the kidneys failed to drain with a full bladder despite 'normal' detrusor pressures. It remains to be seen whether bladder emptying designed to keep the urine volume below the obstructing threshold volume will prevent further loss of renal function.
Hoh
Ivan M Y
IM
Institute of Urology and Nephrology, University College London (UCL), London, UK.
Bomanji
Jamshed B
JB
Nagabhushan
Nagesh
N
Chu
Andrew
A
Ell
Peter J
PJ
Neild
Guy H
GH
Woodhouse
Christopher R J
CR
D000293:Adolescent; D000328:Adult; D000368:Aged; D003558:Cystoscopy; D005260:Female; D005919:Glomerular Filtration Rate / Q000502:physiology; D006801:Humans; D006869:Hydronephrosis / Q000000981:diagnostic imaging* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D011866:Radioisotope Renography / Q000379:methods*; D019275:Radiopharmaceuticals; D017263:Technetium Tc 99m Mertiatide; D001743:Urinary Bladder / Q000503:physiopathology*; D001748:Urinary Bladder Neck Obstruction / Q000000981:diagnostic imaging* / Q000503:physiopathology; D016055:Urinary Retention / Q000503:physiopathology*
D019275:Radiopharmaceuticals; D017263:Technetium Tc 99m Mertiatide