From the Guidelines
A significant residual volume of urine is generally considered to be greater than 100 mL after voiding, as indicated by the most recent guidelines 1.
Key Considerations
- Volumes between 50-100 mL may be borderline concerning, while volumes exceeding 200 mL typically indicate a clinically significant problem requiring intervention.
- Post-void residual (PVR) volume can be measured using either bladder ultrasound or catheterization, with the choice of method depending on patient factors and clinical context 1.
- Elevated residual volumes may indicate urinary retention, which can be caused by bladder outlet obstruction (such as from an enlarged prostate in men), neurogenic bladder dysfunction, or detrusor muscle underactivity.
Management and Complications
- Persistent high residual volumes can lead to complications including urinary tract infections, bladder stones, and kidney damage due to backflow pressure.
- Management depends on the underlying cause and may include medications like alpha-blockers (tamsulosin 0.4 mg daily) for prostatic obstruction, bethanechol (10-50 mg three times daily) to improve bladder contractility, or intermittent catheterization if volumes consistently exceed 300 mL.
- A single elevated measurement should be confirmed with repeat testing, as residual volumes can vary based on fluid intake, time of day, and other factors.
Clinical Decision Making
- Clinicians should consider the patient's overall clinical picture, including symptoms and other diagnostic findings, when interpreting PVR results and making management decisions 1.
- The European Association of Urology guidelines emphasize the importance of monitoring PVR to identify patients at increased risk of acute urinary retention (AUR) 1.
From the Research
Residual Volume Urine Significance
- The significance of residual volume urine is determined by its impact on urinary tract symptoms and the risk of complications such as acute urinary retention and the need for surgical intervention 2, 3, 4.
- A study published in 2024 found that the 90th and 95th percentiles of postvoid residual (PVR) urine volume in healthy adults were 73.2 mL and 102.6 mL for men, and 60.5 mL and 93.8 mL for women, respectively 5.
- These values may serve as the upper limit of normal PVR, and readings above this level may necessitate additional evaluation and treatment 5.
- The relationship between bladder volume and PVR is nonlinear, with PVR increasing significantly when bladder volume is around 528 mL 5.
- Factors that influence PVR include bladder volume, International Prostatic Symptom Score (IPSS), and gender, while age and functional constipation do not have a significant impact 5.
Comparison of Treatment Options
- The use of 5-alpha reductase inhibitors (5-ARIs) in combination with alpha-blockers or phosphodiesterase type 5 inhibitors (PDE5Is) has been shown to improve lower urinary tract symptoms (LUTS) and urinary flow rates in patients with benign prostatic hyperplasia (BPH) 2, 3, 4, 6.
- A study comparing tadalafil/finasteride and tamsulosin/finasteride combination therapies found that both combinations were effective in improving BPH-related LUTS, but tadalafil/finasteride had the advantage of improving sexual performance 6.