Abnormal Post-Void Residual Volume
While there is no universally accepted definition of an abnormal post-void residual (PVR) volume, large PVR volumes (>200-300 ml) may indicate significant bladder dysfunction and predict a less favorable response to treatment. 1
Definition and Clinical Significance
- PVR is the volume of urine remaining in the bladder immediately after completion of voiding 2
- Large PVR volumes (e.g., 350 ml) may indicate bladder dysfunction and predict a slightly less favorable response to treatment 1
- Large PVRs may herald progression of disease, particularly in conditions like benign prostatic hyperplasia (BPH) 1
- No specific PVR "cut-point" has been established for clinical decision-making due to test-retest variability and lack of appropriately designed outcome studies 1
Measurement Techniques
- Ultrasonography is the preferred method for measuring PVR due to its non-invasive nature 2
- The interval between voiding and PVR measurement should be of short duration to ensure accuracy 2
- For confirmation of abnormal findings, PVR measurement should be repeated to improve precision due to marked intra-individual variability 1
- In children, it is recommended to repeat flow/residual urine measurement up to 3 times in the same setting in a well-hydrated child 1
Clinical Implications by Volume
- PVR volumes between 0-300 ml do not predict response to medical therapy for BPH 1
- A study suggested 180 ml as a potential threshold with 87% positive predictive value for bacteriuria in asymptomatic men 3
- However, subsequent research found this 180 ml cutoff had only 28% sensitivity and 94% specificity for predicting urinary tract infections 4
- In patients with overactive bladder (OAB), caution should be used when performing botulinum toxin injection in patients with PVR >100-200 ml 1
- In children with primary nocturnal enuresis, elevated PVR is associated with significantly less favorable response to medical treatment 5
Clinical Applications
- PVR measurement is considered an optional test in the initial evaluation of men with lower urinary tract symptoms (LUTS) 1
- PVR should be measured prior to intradetrusor botulinum toxin therapy for OAB 1
- PVR should be obtained in OAB patients whose symptoms have not adequately improved or worsened after botulinum toxin injection 1
- No level of residual urine, in and of itself, mandates invasive therapy for BPH 1
- Many patients maintain fairly large amounts of residual urine without evidence of urinary tract infection, renal insufficiency, or bothersome symptoms 1
Special Considerations
- PVR measurement is particularly helpful in patients with complex medical histories (e.g., neurologic diseases affecting bladder function) 1
- In children with dysfunctional voiding, treatment of constipation alone resulted in improvement of bladder emptying in 66% of those presenting with increased PVR 1
- Portable ultrasound scanners have shown a sensitivity of 66.7% and specificity of 96.5% in detecting PVR ≥100 ml 6