For people considered likely to have PAH based on the above tests, the specific associated condition is then determined based on the physical examination, medical/family history and further specific diagnostic tests (for example, serological tests to detect underlying connective tissue disease, HIV infection or hepatitis, ultrasonography to confirm the presence of portal hypertension, echocardiography/cardiac magnetic resonance imaging for congenital heart disease, laboratory tests for schistosomiasis, and high resolution CT for PVOD and pulmonary capillary hemangiomatosis). Routine lung biopsy is discouraged in patients with PAH, because of the risk to the patient and because the findings are unlikely to alter the diagnosis and treatment.

If heart disease and lung disease have been excluded, a ventilation/perfusion scan is performed to rule out CTEPH. If unmatched perfusion defects are found, further evaluation by CT pulmonary angiography, right heart catheterization, and selective pulmonary angiography is performed.