CVR Calculator

CVR is a way of estimating the size of a lung lesion compared with a baby’s overall size.

The equation is CVR = (Length × Width × Height × 0.52) ÷ Head Circumference.

Where:

• Length, Width, Height are the lesion dimensions (usually in cm) from ultrasound

• Head Circumference is the baby’s head circumference (also in cm)

• 0.52 is the ellipsoid correction factor—used because the lesion is approximated as an ellipsoid (an oval 3D shape) when estimating volume

A CVR under about 0.8 is generally considered lower risk for complications.

A CVR around 1.6 or higher is generally considered higher risk for complications.

A few important things to know:

CVR is an estimate, not an exact measurement. Small differences in baby’s position, the angle of the ultrasound, or exactly where the cursor is placed can change the measurements from scan to scan. What matters most is the pattern over time: how the CVR is trending across multiple scans, alongside what your team is seeing (for example, any signs of fluid build-up or mass effect).