A normal ventilation scan with an abnormal percussion scan indicates the presence of what condition?

A normal ventilation scan combined with an abnormal percussion scan typically indicates the presence of a pulmonary embolism. In this scenario, the ventilation scan assesses how well air is reaching different parts of the lungs, while the percussion scan evaluates the presence of fluid or other issues in the lung tissue or pleural space.

In the case of a pulmonary embolism, there can be adequate ventilation (normal ventilation scan) because air may still flow into the lungs; however, the underlying vascular issue means that blood flow is obstructed, leading to alterations in how the lung tissue behaves during percussion. This abnormal percussion result can reflect changes in density or the presence of fluid in the affected areas due to the embolism blocking blood supply.

The other conditions listed do not typically present with a normal ventilation scan alongside an abnormal percussion scan. Pneumonia usually shows both ventilation and percussion abnormalities due to infection and fluid accumulation. Chronic bronchitis might reflect changes in ventilation due to airway obstruction, and asthma may lead to ventilatory abnormalities primarily related to airflow limitation. Thus, the specific combination of findings in the scenario provided aligns with a pulmonary embolism diagnosis.