1. What is PVR Calculation?

Post Void Residual (PVR) volume is the amount of urine left in the bladder after urination. Ultrasound-based PVR calculation provides a non-invasive method to estimate this volume using bladder dimensions.

2. How Does the Calculator Work?

The calculator uses the ultrasound-based PVR formula:

Where:

• Length — Maximum bladder length in centimeters
• Width — Maximum bladder width in centimeters
• Height — Maximum bladder height in centimeters
• 0.52 — Correction factor for bladder shape

Explanation: The formula approximates bladder volume by treating it as an ellipsoid shape and applying a correction factor.

3. Importance of PVR Measurement

Details: PVR measurement is crucial for evaluating urinary retention, monitoring bladder function, and assessing treatment effectiveness for lower urinary tract symptoms.

4. Using the Calculator

Tips: Enter bladder dimensions in centimeters as measured by ultrasound. All values must be valid (greater than 0). For best accuracy, measure immediately after voiding.

5. Frequently Asked Questions (FAQ)

Q1: What is a normal PVR volume?
A: Normal PVR is typically less than 50 mL. Volumes over 100-150 mL may indicate urinary retention.

Q2: How accurate is ultrasound PVR measurement?
A: Ultrasound PVR measurement has about ±20% accuracy compared to catheterization, but is non-invasive and convenient.

Q3: When should PVR be measured?
A: PVR should be measured when evaluating urinary retention, incomplete emptying, or monitoring bladder function in neurological conditions.

Q4: Are there limitations to this calculation?
A: Accuracy decreases with irregular bladder shapes or when the bladder is very full or nearly empty.

Q5: How often should PVR be checked?
A: Frequency depends on clinical context - may range from one-time assessment to regular monitoring in chronic conditions.