Interpretation of Post-Void Residual of 14 ml
A post-void residual (PVR) of 14 ml is considered normal and indicates excellent bladder emptying efficiency with no evidence of urinary retention.
Understanding Post-Void Residual Measurements
Post-void residual (PVR) refers to the amount of urine that remains in the bladder after voiding. This measurement is an important diagnostic parameter in the evaluation of lower urinary tract symptoms (LUTS) and bladder function.
Normal PVR Values
- While there is no universally accepted definition of a significant residual urine volume 1, a PVR of 14 ml is well within normal limits
- Large PVR volumes (>200-300 ml) may indicate marked bladder dysfunction 1, 2
- PVR of 14 ml indicates efficient bladder emptying with no evidence of urinary retention
Clinical Significance
A PVR of 14 ml has the following clinical implications:
- Excellent bladder emptying efficiency: The bladder is emptying effectively with minimal residual urine
- No indication of voiding dysfunction: Such a low value does not suggest obstruction or detrusor underactivity
- No contraindication to treatments: This value would not be a contraindication to watchful waiting or medical therapy for conditions like BPH 1
Measurement Considerations
It's important to note several factors regarding PVR measurement:
- Measurement variability: PVR can vary considerably between voids in the same individual 3, 4
- Measurement timing: The interval between voiding and PVR measurement should be short 2
- Measurement method: Ultrasound bladder volume measurement is preferred to urethral catheterization 2
Clinical Context
When interpreting a PVR of 14 ml, consider:
- Not a predictor of BOO: PVR does not specifically indicate presence of bladder outlet obstruction 2
- Not a strong predictor of acute urinary retention: Low PVR values don't guarantee against future retention 2
- May need repetition: One measurement may be unreliable; repeated measurements can confirm consistency 4
Important Caveats
- Normal PVR doesn't exclude all dysfunction: Some studies suggest that patients with voiding dysfunction can have normal PVR values (range 0-50 ml) 5
- Test-retest variability: PVR has significant test-retest variability 1
- Volume dependency: PVR should be interpreted in context of voided volume 3
In conclusion, a PVR of 14 ml indicates normal and efficient bladder emptying. This value would not warrant further investigation of voiding dysfunction in the absence of other concerning symptoms or findings.