Diagnosis of Respiratory Syncytial Virus
Your doctor may suspect respiratory syncytial virus based on the findings of a physical exam and the time of year the symptoms occur. During the exam, the doctor will listen to the lungs with a stethoscope to check for wheezing or other abnormal sounds.

Laboratory and imaging tests aren't usually needed. However, they can help diagnose RSV complications or rule out other conditions that may cause similar symptoms. Tests may include:

Blood tests to check white cell counts or to look for viruses, bacteria and other germs

Chest X-rays to check for lung inflammation

Swab of secretions from inside the mouth or nose to check for signs of the virus

Sometimes, painless skin monitoring (pulse oximetry) to detect lower than normal levels of oxygen in the blood