[Comparison of methods for the diagnosis of urinary obstruction in women]

The International Continence Society does not offer secure guidelines for the diagnosis of micturitional obstruction. The problem has been extensively addressed in relation to male voiding difficulties. Little is known on the subject in female patients. Two criteria for the diagnosis of obstructed micturition are in clinical use. The Sussett formula divides the maximum micturitional pressure by the square of the corresponding maximum urinary flow rate. Two cutoffs, corresponding approximately to the 90th and 95th centiles can be used (0.15, and 0.5). A more complex graphic nomogram developed by Schafer plots maximum flow versus maximum detrusor pressure, identifying obstruction and detrusor dysfunction simultaneously according to the author. We feel that these methods, extensively tested on a male population, can both be used on a female population. We noticed that in some instances the results were different. 469 women referred for micturitional disturbances underwent pressure/flow studies. 62 (13.2%) were obstructed according to the Schafer nomogram, 103 (21.9%) and 31 (6.6%) respectively using the Sussett mathematical formula using two different cutoffs (0.15 and 0.5). The two methods identify the same patients only if micturitional pressures are normal (40 to 60 cmH2O) to high (over 60 cmH2O) and the Sussett formula is used with a higher (95th centile) cutoff. This means that both methods are clearly insufficient in the diagnosis of obstruction if detrusor function is impaired. This can happen in case of chronic retention due to detrusor failure after a long-standing obstruction or for primary failures due to central nervous system lesions. Extreme care should be exercised if pressure-flow studies indicate obstruction at low micturitional pressures.(ABSTRACT TRUNCATED AT 250 WORDS)