Pressure flow analysis may aid in identifying women with outflow obstruction

Purpose: We refined recently developed pressure flow cutoff values for fema le bladder outlet obstruction and applied these values in a consecutive gro up of women undergoing urodynamic testing for various lower urinary tract s ymptoms. Materials and Methods: A total of 87 women with clinical obstruction determ ined by history and presenting complaint were enrolled in our prospective e valuation of pressure flow studies. We identified 3 groups of participants according to the suspected cause of obstruction, including prolapse in 33, previous incontinence surgery in 25, and no likely source of obstruction id entified from history and physical examination only in 29. An additional 12 4 patients presenting for evaluation of stress urinary incontinence served as controls. Optimal cutoff values for determining obstruction were develop ed using receiver operating characteristic curves. To determine the prevale nce of bladder outlet obstruction these values were prospectively applied t o 106 women undergoing urodynamics for various voiding complaints. Results: In controls the average maximum flow rate was 23 cc per second and average detrusor pressure was 21.9 cm. water, whereas the corresponding va lues in those with clinical obstruction were 10.7 cc per second and 40.8 cm . water (p <0.001). No differences were noted in the various obstruction gr oups. Receiver operating characteristics analysis revealed that cutoff valu es of 11 cc per second or less and 21 cm. water or more optimized the selec tion of patients with bladder outlet obstruction. Using these values we not ed a bladder outlet obstruction prevalence of 20% in a consecutive cohort o f women undergoing urodynamic studies at our center. Conclusions: We propose cutoff pressure flow values for identifying women w ith bladder outlet obstruction although they should be used only in conjunc tion with the overall clinical situation. Neither pressure flow data only n or clinical symptoms alone may be sufficient for diagnosing obstruction in women.