Hilum is basically present on the right and left side of the mid-line. They are the indicators where our bronchi (smaller airways) arise from the trachea (main central airway).
There are various causes for prominent hilum -
* The pulmonary artery - for example, pulmonary artery hypertension, secondary to mitral valve disease; chronic pulmonary emboli; or primary pulmonary hypertension. This is usually on one side.
* The main bronchus - carcinoma arising in the proximal bronchus. This is also seen on one side.
* Enlarged lymph nodes - caused by infection, tuberculosis or sarcoidosis. They are present on both of the sides.
In your wife's case most probably according to her symptoms, she might be having prominent hilum on both sides of her chest. Mostly the prominent hilum is seen due to an enlarged lymph node. The cause of this is usually some infection. That is what your doctor wants to confirm by repeating the X-ray at a different angle.
The cause will be confirmed after the second X-ray, depending on whether any blood tests are needed or not. There is normally nothing to worry about, as the cause is usually easily treatable.
I would advise you to get the second X-ray done and then consult your doctor. In the meantime there is no need to panic.