Pneumothorax Size (Collins Method)
Collins pneumothorax-size estimate (Collins 1995): percent = 4.2 + 4.7 × (A + B + C), where A, B, and C are the interpleural distances (cm) at the apex, mid-upper, and mid-lower lung.
Open the calculator → Runs in your browser. Data leaves only if you deliberately send a problem report from the interactive tool.
Example
- Apex interpleural distance
- 2 cm
- Mid-upper interpleural distance
- 3 cm
- Mid-lower interpleural distance
- 2 cm
Result: Estimated pneumothorax size 37.1% of the hemithorax.
The tool opens with these values already filled in. Replace them with your own.
What the result means
- Percent
- % = 4.2 + 4.7 x (A + B + C), interpleural distances (cm) at apex, mid-upper, and mid-lower lung. An estimate, not a chest-tube order.
What you enter
- Apex interpleural distance
- Mid-upper interpleural distance
- Mid-lower interpleural distance
How this is calculated
Collins CD, Lopez A, Mathie A, Wood V, Jackson JE, Roddie ME. Quantification of pneumothorax size on chest radiographs using interpleural distances: regression analysis based on volume measurements from helical CT. AJR Am J Roentgenol. 1995;165(5):1127-1130. Read the source ↗
A reference and educational tool. Not medical, legal, or financial advice, and not a substitute for clinician judgment.