From the Guidelines
Yes, you can have symptoms of bladder outlet obstruction even with a small post-void residual urine volume. Bladder outlet obstruction symptoms typically include weak urine stream, hesitancy, intermittent flow, straining to urinate, and a sense of incomplete emptying. These symptoms are often caused by physical blockage at the bladder neck or urethra, commonly due to conditions like benign prostatic hyperplasia (BPH) in men, urethral strictures, or detrusor-sphincter dyssynergia. A small post-void residual (typically less than 50-100 mL) suggests that despite the obstructive symptoms, your bladder is still able to empty effectively. This can occur in early or mild cases of obstruction, or when the bladder muscle is strong enough to overcome partial obstruction. It's essential to note that symptoms don't always correlate perfectly with objective measurements, as highlighted in a study by el Din et al. 1. If you're experiencing these symptoms, you should still seek medical evaluation as treatment may be beneficial even with a small post-void residual. Treatment options depend on the underlying cause and might include alpha-blockers like tamsulosin (0.4 mg daily), 5-alpha reductase inhibitors like finasteride (5 mg daily) for BPH, or procedures to relieve obstruction in more severe cases, as discussed in the European Association of Urology guidelines 1. The most recent guidelines from 2023 emphasize the importance of a comprehensive evaluation, including the consideration of bladder outlet obstruction and detrusor overactivity, in the management of lower urinary tract symptoms in men 1. In clinical practice, the management of bladder outlet obstruction should prioritize the alleviation of symptoms and the improvement of quality of life, while also considering the potential risks and benefits of different treatment options, as recommended by the European Association of Urology guidelines 1.
From the Research
Bladder Outlet Obstruction Symptoms
- Bladder outlet obstruction (BOO) can cause various symptoms, including obstructive and irritative urinary tract symptoms, such as dysuria, increased frequency and urgency of urination, and recurrent urinary tract infections 2.
- These symptoms can be similar to those caused by other urinary problems, making it challenging to diagnose BOO based on symptoms alone 3, 4.
Post Void Urine Volume
- A small post-void urine volume does not necessarily rule out BOO, as the condition can still be present even with a small residual volume 5.
- The correlation between urine volumes measured by a bladder scanner and those measured by bladder catheterization is high, with a summary correlation coefficient of 0.93 5.
- Non-invasive diagnostic methods, such as intravesical prostatic protrusion (IPP), detrusor wall thickness (DWT), prostate volume (PV), and serum prostate specific antigen (PSA) levels, can be used to detect BOO and predict acute urinary retention (AUR) secondary to benign prostatic enlargement 6.
Diagnosis of Bladder Outlet Obstruction
- The gold standard for diagnosing BOO is urodynamic studies (UDS), which measure detrusor pressure and urinary flow 2.
- However, UDS is an invasive test and is associated with risks for urinary tract infections, bothersome urinary symptoms, and hematuria 2.
- Non-invasive diagnostic methods are being developed, but their main limitation is the variability in threshold values, highlighting the need for further standardization of measurement protocols 2.