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Impact of persistent bladder outlet obstruction on bladder function in male BPH patients

Introduction & Objectives

Bladder Outlet Obstruction (BOO) is a common problem among elderly men. It is known that persistent BOO can affect bladder function. We aimed to evaluate the long-term impact of persistent BOO on bladder function using urodynamic profiles.

Materials & Methods

We analyzed the prospectively collected urodynamic database of Seoul National University Hospital about 19000 cases over 20 years. We included male patients aged 40 years or older with non-neurogenic LUTS/BPH who have repeated urodynamic studies 2 or more times and had persisted BOO in both studies. BOO defined as BOO index (PdetQmax – 2Qmax) > 40. First and repeat UDS profiles were compared, including post-void residual, bladder sensation, bladder compliance, bladder capacity, involuntary detrusor contraction, bladder contractility index (PdetQmax + 5Qmax), and voiding efficiency (post-void residual/(voided volume + post-void residual)). The student’s t-test and Chi-square test were used as appropriate.


A total of 37 patients were included in our analysis. The mean age at repeat UDS was 69. The mean time interval between the two studies was 61 months. UDS profiles tended to deteriorate over time. Mean bladder compliance decreased from (64.53ml/cmH2O) to (41.92ml/cmH2O) (p<0.01). The mean volume to induce normal desire to void decreased from (247.78ml) to (185.23ml) (p=0.01). Mean bladder capacity decreased from (359.84ml) to (283.75ml) (p=0.01). The mean bladder contractility index decreased from (108.36) to (99.08), though not reaching statistical significance (p=0.13). Rate of involuntary detrusor contraction increased from (24.32%) to (69.44%) (p<0.01).


Our results show that persistent BOO induced functional-urodynamic deteriorations in the bladder function, such as reduced capacity, decreased compliance, and induced detrusor overactivity. In patients with LUTS/BPH with confirmed BOO, more active treatment should be considered.