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The comparative pressure‐flow plot properties of radiological bladder neck and prostatic obstruction
Author(s) -
Idriz Sanjin,
Bishara Samuel,
Kirkham Alex,
Rickards David,
Julian P.,
Shah R.,
MaloneLee James
Publication year - 2009
Publication title -
bju international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.773
H-Index - 148
eISSN - 1464-410X
pISSN - 1464-4096
DOI - 10.1111/j.1464-410x.2009.08679.x
Subject(s) - confidence interval , urination , medicine , urology , urinary flow , bladder outlet obstruction , neck of urinary bladder , nuclear medicine , urinary bladder , prostate , urinary system , cancer
OBJECTIVES To test the hypotheses that: (i) significant differences should exist in pressure/flow data between radiologically determined bladder neck and prostatic obstruction; (ii) these differences should inform understanding of the pathophysiology of male outflow obstruction. The biomechanics of the voiding/pressure/flow plot imply that a urodynamic assessment trace should identify outflow obstruction and characterise the urethral viscoelastic properties. Micturating cystourethrograms (MCUG) images might provide a useful diagnostic dichotomy for testing these assumptions. MATERIALS AND METHODS The pressure/flow data from 71 men who also provided video‐urodynamic imaging data that a radiologist could classify unequivocally as showing bladder neck obstruction (42) or prostatic obstruction (29) were analysed. The following variables were recorded: the detrusor pressure at initiation of voiding (P det.open ); the detrusor pressure at the end of voiding (P det.close ); the detrusor pressure at maximum flow rate (Q max ), (P det. Q max ), and Q max . The urethral resistance relation (URR) was drawn onto the pressure‐flow plot and the gradient of the URR, ΔP det /ΔQ, was calculated. RESULTS There were significant between group differences in P det.open (95% confidence interval of the difference 5.2–28.6, U = 352, P = 0.003); P det.close (0.2–15.0, U = 428, P = 0.034); P det .Q max (0.0–18.9, U = 439, P = 0.05); Q max and ΔP det /ΔQ did not distinguish between the MCUG groups (95% confidence interval of the difference 2.3–18, U = 111; P = 0.004). The best‐fit model from linear combinations of the data achieved an area under the receiver operator curve of 0.72 for discriminating between the MCUG groups. CONCLUSIONS The urodynamic assessment identified interesting and coherent biomechanical differences, and could distinguish between the obstructions with a moderate degree of accuracy.