Hypothesis / aims of study
To compare post void residual (PVR) urine values measured after pressure flow studies (PFS) with spontaneous PVR measurements obtained at any time point. To evaluate these two PVR measurement approaches, obstruction and contractility indices obtained during PFS were utilized.
Study design, materials and methods
We retrospectively analysed men with non-neurogenic lower urinary tract symptoms undergoing PFS between 2018–2024. Patients were classified using both the Abrams–Griffiths (AG) nomogram and UPSTREAM derived thresholds. Subgroups stratified according to obstruction and contractility status were compared in terms of lower urinary tract parameters, particularly PVR values measured after spontaneous voiding and those measured after PFS. In addition, the ability of specific PVR threshold values to discriminate between obstruction and contractility states was analysed using classifications based on nomograms.
Results
A total of 227 men were included (median age: 62 years). According to the AG classification, post PFS PVR volumes were significantly higher in patients with detrusor underactivity (DU) (p=0.012), whereas spontaneous PVR did not differ between contractility groups. According to the AG classification, both spontaneous and post-PFS PVR volumes were significantly higher in obstructive patients (p=0.001 and p=0.036, respectively). Under the UPSTREAM classification, only spontaneous PVR remained significantly higher in the obstructive group (p=0.003). Post PFS PVR >100 mL was significantly more frequent in underactive patients across both AG and UPSTREAM classifications and, according to AG, in obstructive patients. In addition, post PFS PVR >200 mL was significantly associated with DU in the UPSTREAM classification.
Interpretation of results
These findings suggest that post-PFS PVR may provide additional diagnostic value, particularly for identifying detrusor underactivity, whereas spontaneous PVR appears more closely related to obstruction.