Research Article: Video-urodynamic characteristics of non-neurogenic, idiopathic underactive bladder in men – A comparison of men with normal tracing and bladder outlet obstruction

Date Published: April 4, 2017

Publisher: Public Library of Science

Author(s): Yuan-Hong Jiang, Hann-Chorng Kuo, Robert Hurst.


Underactive bladder is frequently encountered in elderly patients. It may result from detrusor underactivity (DU) or low detrusor contractility due to a urethral sphincter inhibitory effect. This study analyzed the video-urodynamic study (VUDS) characteristics of patients with underactive bladder in a large cohort of men with lower urinary tract symptoms (LUTS).

Male patients with LUTS who had failed the initial treatment were consecutively enrolled. All patients underwent detailed urological investigations including prostate measurement, free uroflowmetry, post-void residual volume (PVR) measurement, cystoscopy and VUDS. The VUDS characteristics of the men with underactive bladder were analyzed and compared with those of men with bladder outlet obstruction and normal tracing.

A total of 1329 men who underwent VUDS were included in this retrospective analysis. After VUDS, the final diagnosis was DU in 165 patients, poor relaxation of external sphincter (PRES) in 525, bladder outlet obstruction in 501, and normal tracing in 138. VUDS findings in DU patients showed a slowly increased detrusor pressure, intermittent detrusor contractions, or early decline of detrusor contraction, resulting in a low maximum flow rate (Qmax), and large PVR. In comparison with the PRES groups, DU patients were older, had reduced bladder sensation, lower detrusor pressure (Pdet), lower Qmax, larger PVR volume, and lower voiding efficiency. Patients with urodynamic PRES also had low-pressure–low-flow tracings, but their bladder sensation was similar to that with normal tracing. DU patients with very low Pdet also had low detrusor tonicity, and more medical co-morbidities than the other groups did.

Idiopathic underactive bladder in elderly men could be attributed to urodynamic DU and PRES. DU is associated with old age, reduced bladder sensation, low voiding efficiency, and medical co-morbidities.

Partial Text

Underactive bladder is frequently encountered in elderly patients with chronic medical or neurological diseases. Underactive bladder causes lower urinary tract symptoms (LUTS) of hesitancy, slow stream, dysuria, and incomplete voiding. Patients with underactive bladder might have low detrusor contractility or a non-contractile detrusor; both are known as forms of detrusor underactivity (DU) in urodynamic terminology. In patients with DU, chronic urinary retention or large post-void residual (PVR) volume is frequently noted, which is usually difficult to manage. The pathophysiology of underactive bladder may involve neurogenic, myogenic, and bladder outlet pathologies [1]. Recent studies also reveal that urothelial dysfunction of the urinary bladder may be associated with impaired bladder sensation as well as impaired detrusor contractility [2].

Men with persistent LUTS who had failed the initial medical treatment were consecutively enrolled to undergo VUDS to obtain a better differential diagnosis of their vesicourethral dysfunction. The patients with overt clinical diagnosis of BOO due to a large prostate and large PVR, acute urinary retention, overt neuropathy such as stroke, Parkinson’s disease, spinal cord injury, presence of bladder stones, and acute urinary tract infection were excluded.

In this retrospective study, 1329 men who had undergone VUDS were included. After VUDS, the final diagnosis was DU in 165 men, PRES in 525, BOO in 501, and normal VUDS tracing in 138 men. The BOO group included patients with benign prostatic obstruction (n = 205/501, 40.9%), BND (n = 283/501, 56.5%), and urethral stricture (n = 13/501, 2.6%).

This study demonstrates that low-pressure–low-flow underactive bladder involves urodynamic DU and PRES. Both lower urinary tract dysfunctions result in low Qmax, increased PVR and LUTS including slow stream and dysuria. However, the urodynamic characteristics of DU and PRES differ for bladder sensation, voiding pressure, and VE. Urodynamic DU is associated with reduced bladder sensation and a larger cystometric bladder capacity than PRES or BOO. These urodynamic characteristics may help urologists in the diagnosis of underactive bladder and with decisions on its treatment.

Idiopathic underactive bladder may be attributed to urodynamic DU and PRES. DU is associated with older age, reduced bladder sensation, and medical comorbidities. DU patients with very low voiding pressure also have low detrusor tonicity and a large PVR in addition to diminished bladder sensation. VUDS provides information to determine the vesicourethral dysfunction in men with underactive bladder. Videourodynamic data also aid in determining treatment options.