Diagnosis:

Patients should see a doctor if they have sinusitis symptoms that do not clear up within a few days, are severe, or are accompanied by high fever or acute illness. However, only one-half to two-thirds of patients with such symptoms actually have sinusitis. Some experts complain that too many patients are diagnosed with true sinusitis and given unnecessary antibiotics when their symptoms would actually resolve easily in days with over-the-counter medications or no drugs at all. Others believe that true sinusitis is often mistakenly diagnosed as an allergy and not treated, which could lead to serious illness.

The first goal in diagnosing sinusitis is to rule out other possible causes of symptoms, and then determine:

• The site where the infection has occurred
• Whether the condition is acute or chronic
• The organism causing the infection (if possible)

Diagnostic Approach to Acute Sinusitis

Medical History. The patient should describe all symptoms such as nasal discharge and specific pain in the face and head, including eye and tooth pain.

After assessing symptoms, the doctor should take a thorough medical history of the patient:

• Any history of allergies or headaches
• Recent upper respiratory infection (colds, flus, infection)
• History of sinusitis episodes that is unresponsive to antibiotic treatment. (In such cases, the doctor will usually diagnose chronic or recurrent acute sinusitis and refer the patient to a specialist for more advanced testing.)
• Exposure to cigarette smoke or other environmental pollutants
• Recent travel
• Recent dental procedures, particularly if there is pain toward the back of the mouth
• Medications being taken (particularly decongestants)
• Any known structural abnormalities in the nose and face
• Injury to the head or face
• History of medical conditions, such as chronic fatigue syndrome or fibromyalgia, which can produce tender areas in the face or sinus regions and nonspecific symptoms of ill health
• Any family history of allergies, immune disorders, cystic fibrosis, or immotile cilia syndrome
• In small children with sinusitis, whether they attend a day care center or nursery school

Physical Examination

The doctor will press the forehead and cheekbones to check for tenderness and check for other signs of sinusitis, including yellow to yellow-green nasal discharge. The doctor will also check the inside of the nasal passages using a device with a bright light to check the mucus and look for any structural abnormalities.

Laboratory Tests

In some cases, tests may be used to detect that presence of immune factors in sinus tissues that would suggest persistent inflammation. Such findings would strongly suggest a chronic or allergic condition. In 2005, a new laboratory test became available for diagnosing chronic sinusitis. The CRS Fungal Profile tests mucus samples for eosinophil major basic protein (a protein involved in allergic and inflammatory reactions) and a type of fungi. However, more research is necessary before results from this test, and related tests, can be used to start treatment with antifungal medications.

Nasal Endoscopy (Rhinoscopy)

Nasal endoscopy, or rhinoscopy, is now used for diagnosing chronic and recurrent acute sinusitis and for differentiating between allergies and true acute sinusitis. It involves the insertion of a flexible tube into the nasal passage and the use of a fiberoptic light that enables the doctor to see inside the sinuses. Endoscopy allows detection of even very small abnormalities in the sinuses. It can determine whether surgery is necessary and if medications are having any effect. Bacterial cultures can also be taken from samples removed using endoscopy. (Endoscopy is also used for treating sinusitis.)

Imaging Techniques

Computer Tomography. Computed tomography (CT) scanning is the best method for viewing the paranasal sinuses. There is little relationship, however, between symptoms in most patients and findings of abnormalities on a CT scan. CT scans are recommended for acute sinusitis only if there is a severe infection, complications, or a high risk for complications. CT scans are useful for diagnosing chronic or recurrent acute sinusitis and for surgeons as a guide during surgery. They show inflammation and swelling and the extent of the infection, including in deeply hidden air chambers missed by x-rays and nasal endoscopy. Often, they can detect the presence of fungal infections.

X-Rays. Until the availability of endoscopy and CT scans, x-rays were commonly used. They are not as accurate, however, in identifying abnormalities in the sinuses. For example, more than one x-ray is needed for diagnosing frontal and sphenoid sinusitis. X-rays do not detect ethmoid sinusitis at all. This area can be the primary site of an infection that has spread to the maxillary or frontal sinuses.

Magnetic Resonance Imaging. Magnetic resonance imaging (MRI) is not as effective as CT in defining the paranasal anatomy and therefore is not typically used to image the sinuses for suspected sinusitis. MRI is also more expensive than CT. However, it can help rule out fungal sinusitis and may help differentiate between inflammatory disease, malignant tumors, and complications within the skull. It may also be useful for showing soft tissue involvement.

Sinus Puncture and Bacterial Culture

Sinus puncture with bacterial culture is the gold standard for diagnosing a bacterial sinus infection. It is invasive, however, and is performed only when antibiotics have not worked. Sinus puncture involves using a needle to withdraw a small amount of fluid from the sinuses. It requires a local anesthetic and is performed by a specialist. The fluid is then cultured to determine what type of bacteria is causing sinusitis.