A helpful way to work through this question is to think about which of these four conditions is actually located in the calf, since that is where the Homans sign test applies pressure.
- Deep venous thrombosis: This condition is a blood clot inside a deep vein of the leg, most often in the calf. Since the Homans manoeuvre stretches exactly this area, pain on this movement is read as a sign that a clot may be present there.
- Pulmonary embolism: This is a clot that has already broken loose and travelled to the lungs, so by the time it happens, the clot is no longer in the calf for a leg stretch test to detect.
- Stroke: This affects blood flow in the brain, an entirely different part of the body from the calf being tested here.
- Pneumothorax: This is air trapped in the space around the lung, again unrelated to the leg or its veins.
Because the Homans sign specifically tests the calf where a leg vein clot would sit, a positive result is interpreted as deep venous thrombosis.
Therefore, the correct answer is Deep venous thrombosis.