Diagnosis of sinusitis is usually based on your medical history and physical examination. A detailed history of the problem often can be of more value to the diagnosis than a physical exam. If the symptoms and physical findings are typical of sinusitis, further testing is usually not needed.

Additional tests may be done if:

• The diagnosis is not clear.
• Antibiotic treatment has failed to clear up the problem.
• Complications (such as a bone infection) are suspected.
• Surgery is being considered.

Imaging tests may be used when symptoms of sinusitis persist or recur despite treatment, or to look for tumors or other growths when there is bleeding or bloody discharge from the nose. They include:

• Computed tomography (CT) scan of the head and face, which provides a detailed image of sinus structures. A CT scan may help evaluate severe or chronic sinusitis, identify suspected complications of sinusitis, or rule out other conditions. It is not used to diagnose acute sinusitis.
• Sinus X-ray, which may be done to confirm a suspected case of sinusitis. An X-ray produces a picture of dense tissues inside the body. But a CT scan may provide better information.

Less often, other tests may be done by an ear, nose, and throat (ENT) specialist (also called an otolaryngologist) or by an allergist. These tests may include:

• An endoscopic sinus exam (ESM) (nasal endoscopy). An ESM uses a lighted viewing instrument called an endoscope to view structures inside your nose and sinus cavities. ESM is used to evaluate chronic sinusitis.
• A needle puncture and aspiration of sinus contents, followed by nasal culture to identify the bacteria or fungus causing the problem.
• A magnetic resonance imaging (MRI). An MRI may be done if there is reason to believe that an infection has spread beyond the sinuses. It may also be helpful in evaluating growths or tumors inside the nose or sinuses.