From the Guidelines
A normal post void residual (PVR) is typically less than 100 milliliters of urine remaining in the bladder after urination. This value is considered acceptable in adults, as stated in the guidelines 1. PVR measurement is an important diagnostic tool that helps assess bladder emptying efficiency. The test is performed either by catheterization shortly after urination or through bladder ultrasound, which is non-invasive and preferred when available.
Key Points to Consider
- Higher residual volumes may indicate problems with bladder function, such as urinary retention, which can be caused by obstruction (like enlarged prostate in men), neurological conditions affecting the bladder, or certain medications.
- Regular monitoring of PVR is particularly important in patients with recurrent urinary tract infections, urinary incontinence, or symptoms of incomplete bladder emptying.
- If elevated PVR values are found, further evaluation is typically needed to determine the underlying cause and appropriate treatment, as suggested by the guidelines 1.
Diagnostic Considerations
- Clinicians may perform PVR in patients with LUTS as a safety measure to rule out significant urinary retention both initially and during follow-up 1.
- An elevated PVR cannot be used alone to differentiate between obstructive and non-obstructive conditions, and a definition of exactly what constitutes an elevated PVR has not been agreed upon 1.
Treatment Implications
- The potential benefits of measuring PVR include identifying patients with significant urinary retention and thus decreasing potential morbidity, as well as facilitating selection and implementation of treatment and monitoring treatment outcomes 1.
- The risks/harms of assessing PVR using catheterization are low and include urinary tract infection and urethral trauma, which can be eliminated with ultrasound determination of PVR 1.
From the Research
Normal Post Void Residual (PVR) Values
- The normal PVR value can vary depending on age and gender, as shown in a study published in the Journal of Pediatric Urology 2.
- For males aged 12-14 years, a PVR of >20 ml (7% of bladder volume) is considered elevated, while for males aged 15-18 years, a PVR of >20 ml (7% of bladder volume) is also considered elevated 2.
- For females aged 12-14 years, a PVR of >25 ml (9% of bladder volume) is considered elevated, while for females aged 15-18 years, a PVR of >35 ml (10% of bladder volume) is considered elevated 2.
- Another study published in the Turkish Journal of Obstetrics and Gynecology found that patients with overactive bladder and elevated PVR (>100 ml) had increased maximum bladder capacity compared to those with normal PVR (<100 ml) 3.
Post Void Residual (PVR) in Different Conditions
- A study published in Archivio Italiano di Urologia, Andrologia found that finasteride monotherapy reduced prostate volume and improved International Prostate Symptom Score (IPSS) and maximum urinary flow rate (Qmax) in patients with benign prostatic hyperplasia (BPH) 4.
- A meta-analysis published in PLoS One found that 5-alpha-reductase inhibitor (5ARI) monotherapy improved IPSS, Qmax, and prostate volume in patients with BPH, but had a small effect size and was associated with a higher risk of adverse events such as decreased libido and impotence 5.
- However, it's worth noting that the study published in the Journal of Pediatric Urology 2 provides more specific guidance on normal PVR values for adolescents, while the other studies focus on adults with different conditions.
Key Findings
- Age- and gender-specific reference values should be used when evaluating PVR 2.
- Elevated PVR is a significant risk factor for urinary tract infections (UTI) and can be a predictor of treatment outcomes in certain conditions 2.
- Further research is needed to determine the normal PVR values for different age groups and to evaluate the effectiveness of different treatments for conditions associated with elevated PVR.