Your health care provider will examine you and ask you what symptoms you have, how bad they are, and how long you have had them. Just an examination and your medical history are usually enough to tell your health care provider whether you have sinusitis and need treatment.

Typically, your health care provider will try to determine if the cause of your sinusitis is a viral or bacterial infection. The symptoms of bacterial and viral sinusitis are similar. A diagnosis of bacterial sinusitis is generally made when symptoms have been present for 7 days or more, particularly if symptoms have shown no improvement.

What diagnostic tests might be performed?
Sometimes your health care provider needs additional tests to properly diagnose your sinusitis and determine treatment.

Endoscopy
Your health care provider may examine your nose and sinuses through an endoscope. The endoscope is a fiberoptic device that can look around corners and inside the cavities. During this exam, your health care provider may also take a sample of the discharge from your sinuses. A laboratory will then run some tests on this sample to find out if bacteria are present.

X-ray
When the sinuses are inflamed, the inner lining or mucosa becomes thicker, and this change can show up on an x-ray. In addition, as your sinusitis gets worse, the normally hollow sinus cavities begin to fill up with mucus and inflammatory cells. This makes the sinuses less transparent on the x-ray.

CT or MRI
To get an even better look, your health care provider may order a computed tomography (CT) scan or a magnetic resonance imaging (MRI) film.

Sinus puncture
Occasionally a sinus puncture is performed. During a sinus puncture, a needle is inserted into the sinus through the bone next to the nose. The surgeon then removes a small sample of the sinus fluid. Typically the patient receives local anesthesia to numb the area where the needle will be inserted. Someone in a laboratory then examines the fluid and identifies the type of bacteria or other germ that is causing the sinusitis.

If it is not sinusitis, what else could it be?
Other illnesses, like allergies, asthma, tooth disorders, and migraines and other headaches have some of the same symptoms as sinusitis.