sinus infection is present or not. Indeed, I NEVER order a sinus x-ray. Just how unreliable are sinus x-rays?
In adults, it may be literally a flip of the coin whether the sinus x-ray is providing a correct diagnosis compared with the gold standard CT sinus.
Depending on what study you look at, the specificity of a sinus x-ray hovers around 50% (how often it correctly states normal sinuses). Sensitivity is a little better at around 80% (how often it correctly detects actual sinusitis).
Several studies have concluded that sinus plain film x-rays are unreliable and no longer routinely indicated for the evaluation of nasal and paranasal sinus disease. When radiographic evaluation is indicated a limited CT series provides superior information.
Take home message?
Do not order a sinus x-ray when evaluating for sinus disease/sinusitis!!! Why bother ordering a test that is going to be wrong almost half the time?
(If a CT sinus comes back normal, the patient most definitely does NOT have acute or chronic sinusitis.)
Interestingly, sinus x-rays in kids (2+ years old) may be more reliable and in this sub-population, may be beneficial [Link]. But this study unfortunately did not include CT sinus scans to verify sinus x-ray findings. It should also be noted that sinus x-rays younger than 2 years old is also unreliable [Link].
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Comparison of sinus x-rays with computed tomography scans in acute sinusitis. Acad Emerg Med. 1 (3), 235-9. 1994
Sinusitis and chronic cough in children. J Asthma Allergy 5:27-32. 2012.
Maxillary sinus radiographs in children with nonrespiratory complaints. Pediatrics. 1984;73(3):306–308.