Diagnosing sinusitis depends on a specific history, a thorough physical exam of the sinuses including using a nasopharyngolaryngoscope and finally a radiographic exam by CT. CT of the sinuses is not always required for diagnosis if history, physical and nasopharyngolaryngoscopy are convincing. CT scans are often helpful when symptoms are vague, physical and endoscopic findings are not conclusive, or the response to therapy is poor. Additional laboratory tests may also be important in identifying causes of sinusitis.
Your doctor may use several techniques to diagnose acute sinusitis. Tenderness (pain) near the sinuses may be provoked during examination by applying direct pressure over the affected sinuses. The absence of facial tenderness, however, does not rule out acute sinus infection. Most physicians will examine the nose and throat with a light source. This allows a physician to see about 1 inch into the nose. Nasal discharge, turbinate membrane congestion and inflamed nasal membranes may be seen in the nose. Post nasal drip may also be seen in the throat. However such nasal examination will not reveal some of the most important drainage areas of the sinuses such as the osteomeatal complex and the sphenoethmoid recess (where the sphenoid and posterior ethmoid sinuses drain).
A much better examination of the sinus openings is performed with a nasopharyngolaryngoscope. A nasopharyngolaryngoscope is a very thin (about 3 - 4 millimeters [1/10 inch] in diameter) flexible fiberoptic endoscope (tube-like optical telescope). This instrument allows for direct visualization of the nasal septum, turbinates, mucosa, adenoids, eustachian tube opening, tonsils, back of the tongue, epiglottis and vocal cords. The doctor first applies nasal decongestants and an anesthetic to the nasal passageway. Using this instrument, the doctor then can directly examine the anatomy of the entire nose, including the sinus openings (ostia). The exam lasts only a few minutes. After the exam, you may feel numbness in the nose and throat for up to an hour. An endoscopic exam may reveal pus (infected mucus) in the osteomeatal complex. Pus may also be seen in the sphenoid and posterior ethmoid sinus drainage sites. Pus may be noted in these areas even when a computerized tomography (CT) scan of the sinuses does not show evidence of infection or inflammation. Therefore the most accurate diagnosis will result from both endoscopic exam in which the upper airway is directly visualized combined with the results of CT scans.
Nasal Cytology and Biopsy
Nasal cytology (examination of nasal secretions) or biopsied nasal tissue can be looked at under a microscope for diagnostic purposes. Nasal cytology involves the microscopic examination of nasal mucus obtained by blowing the nose into plastic wrap or introducing a cotton tipped swab into the nose. Results of cytology may help in the assessment of types of nasal and sinus inflammation but are never 100% diagnostic. This limitation prevents its common use. Biopsies are more definitive and can help if there is a question of cancer, invasive fungal disease, or for ruling in or out other unusual causes of sinusitis (ciliary disease, granulomatous disease).
CT Scan of Sinuses
MRI of Sinuses
X-Ray and Ultrasound of Sinuses