How Is Sinusitis Diagnosed? Tests, Criteria & Process
Sinusitis diagnosis relies on Full blood count (FBC), Comprehensive metabolic panel (electrolytes, creatinine, LFTs), Urinalysis. Learn the full diagnostic pathway, clinical criteria, differential workup, and what to expect at your evaluation.
Updated March 27, 2026
Sinusitis is diagnosed using Full blood count (FBC), Comprehensive metabolic panel (electrolytes, creatinine, LFTs), Urinalysis and targeted clinical evaluation. Sinusitis is inflammation of the sinuses, often following a cold or allergy. It causes facial pain, nasal congestion, thick nasal discharge, and reduced sense of smell. Acute sinusitis lasts up to 4 weeks; chronic sinusitis persists over 12 weeks.
Clinical Context
The diagnostic process for Sinusitis begins with Thorough history and physical examination followed by basic blood and urine tests; targeted specialist investigation as needed. Key investigations include Full blood count (FBC), Comprehensive metabolic panel (electrolytes, creatinine, LFTs), Urinalysis, Chest X-ray. The gold standard is: Directed investigation based on clinical history and physical examination findings. Clinical guidelines from NICE / BMJ Best Practice / WHO define the diagnostic criteria and recommended investigation pathway.
Clinical Pathway
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How Is Sinusitis Diagnosed? Tests, Criteria & Process?+
Sinusitis is diagnosed using Full blood count (FBC), Comprehensive metabolic panel (electrolytes, creatinine, LFTs), Urinalysis and targeted clinical evaluation. Sinusitis is inflammation of the sinuses, often following a cold or allergy. It causes facial pain, nasal congestion, thick nasal discharge, and reduced sense of smell. Acute sinusitis lasts up to 4 weeks; chronic sinusitis persists over 12 weeks.
How do doctors test for sinusitis?+
The main tests used to diagnose Sinusitis include Full blood count (FBC), Comprehensive metabolic panel (electrolytes, creatinine, LFTs), Urinalysis. Your doctor will select investigations based on your symptoms, clinical findings, and risk factors.
How long does it take to diagnose Sinusitis?+
The time to diagnosis varies. Some cases are identified within hours using clinical presentation and blood tests; others require weeks, repeated investigations, or specialist referral.
Can Sinusitis be missed on initial testing?+
Yes — Sinusitis can be missed if initial tests are negative or if the presentation is atypical. If clinical suspicion remains high, repeat testing or specialist referral is appropriate.
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