Maxillary Sinus Aspirate Culture and Sensitivity (with Antimicrobial Susceptibility Testing)

Why This Test Is Done

Your doctor may order this test if you have persistent sinus symptoms—such as facial pain, nasal congestion, or thick mucus—that don’t improve with over-the-counter treatments. It’s especially useful for diagnosing sinus infections caused by bacteria, which require prescription antibiotics.

What to Expect Before the Test

You’ll likely be asked to rinse your mouth with saline or an antiseptic solution before the procedure. The test involves inserting a small needle into your maxillary sinus through your cheek to collect fluid. It’s generally quick and not painful, but you may feel mild pressure.

What Happens During the Test

The collected fluid is sent to a lab where it’s cultured to grow bacteria (if present) and tested for antibiotic resistance. Results can take several days to a week, depending on lab processing times.

What the Results Mean

Positive results show bacterial growth, confirming a sinus infection. The antibiotic susceptibility report tells your doctor which medications are most effective against the identified bacteria, helping tailor your treatment plan.