Why would a pulmonary ventilation/perfusion scan be performed?

Pulmonary Embolism: The main reason to perform a pulmonary ventilation-perfusion (v-q) scan is to rule out the presence of a pulmonary embolus (commonly a blood clot). There are several forms of pulmonary thrombo-embolism, but the most common situation is one of sudden onset, leading to sob. Chronic thrombo-embolism leads to development of sob over a long period and it can also be diagnosed with a v-q scan.

Pulmonary Embolism: Typically, the person who gets a lung ventilation perfusion scan is being evaluated for possible pulmonary embolism, to help guide medical management.