Nasal polyps are typically diagnosed through a combination of a physical exam, nasal endoscopy, and sometimes a CT scan. In many cases, a doctor can spot polyps just by looking inside your nose with a lighted instrument, but confirming their extent and ruling out other conditions often requires additional steps.
What Happens During the Initial Exam
Your doctor will start by asking about your symptoms: how long you’ve had nasal congestion, whether you’ve lost your sense of smell, and whether the blockage affects one side or both. They’ll also ask about your history of allergies, asthma, and any sensitivity to aspirin or similar pain relievers, since these conditions frequently overlap with nasal polyps.
A basic look inside your nose with a handheld light can sometimes reveal larger polyps near the front of the nasal passages. Polyps typically appear as pale, grayish, teardrop-shaped growths that are soft and painless. But many polyps sit deeper in the sinuses where a simple visual check can’t reach, which is why endoscopy is the standard next step.
Nasal Endoscopy: The Key Diagnostic Tool
Nasal endoscopy is the most reliable way to confirm nasal polyps. It involves threading a narrow, flexible tube with a tiny camera and light on the end into your nostril. The procedure takes only a few minutes, is done in the office, and doesn’t require sedation. Your doctor will usually spray a numbing and decongestant solution into your nose beforehand to reduce discomfort and open the passages.
Through the camera, the doctor gets a magnified, well-lit view of the entire nasal cavity and the openings to the sinuses. They can see the size, number, and location of any polyps, along with signs of inflammation, mucus buildup, or structural issues like a deviated septum. This direct visualization is what separates a suspected diagnosis from a confirmed one.
When a CT Scan Is Needed
If polyps are confirmed or strongly suspected, your doctor may order a CT scan of the sinuses. This isn’t always necessary for an initial diagnosis, but it becomes important in a few situations: when surgery is being considered, when polyps don’t respond to treatment, or when the full extent of sinus involvement needs to be mapped out.
CT imaging excels at showing exactly which sinuses are blocked or filled with inflamed tissue. It also reveals anatomical details that endoscopy can’t capture, like the bone structures around the sinuses and any variants that might contribute to drainage problems. In people with nasal polyps, the ethmoid sinuses (the small honeycomb-like sinuses between the eyes) tend to be more heavily affected than the larger maxillary sinuses below the cheeks. The degree of sinus blockage visible on a CT scan correlates strongly with polyp severity, giving doctors an objective way to gauge how advanced the disease is.
Red Flags That Require Further Testing
Most nasal polyps are benign inflammatory growths that appear on both sides of the nose. But when a growth appears on only one side, doctors pay closer attention. Unilateral masses can look identical to ordinary polyps but may turn out to be something else entirely, including benign tumors like inverted papillomas or, rarely, cancerous growths.
If a mass is one-sided, unusually firm, bleeding, or growing rapidly, your doctor will likely recommend imaging along with a biopsy. During a biopsy, a small tissue sample is removed and examined under a microscope. This is the only way to definitively rule out a more serious condition. Growths that are present from birth also warrant additional investigation.
Screening for Related Conditions
A polyp diagnosis doesn’t end with identifying the polyps themselves. Because nasal polyps frequently occur alongside other conditions, your doctor may run additional tests to understand the bigger picture.
Aspirin-Exacerbated Respiratory Disease
About 10 to 15 percent of people with nasal polyps also have a condition that combines adult-onset asthma, nasal polyps, and reactions to aspirin or ibuprofen. This triad, sometimes called Samter’s triad, leads to particularly aggressive polyp growth and frequent recurrence after surgery. Diagnosis is based largely on clinical history: adult-onset asthma symptoms, bilateral nasal polyps, and a history of respiratory reactions to common pain relievers. Notably, loss of smell in someone with asthma is a strong clue. Reporting that you can’t smell well has roughly an 80% chance of correctly predicting the presence of nasal polyps, which should prompt referral to a specialist.
Allergies
Allergy testing through skin pricks or blood tests helps determine whether allergic inflammation is contributing to your polyps. While allergies don’t directly cause nasal polyps, they worsen the underlying inflammation and can make polyps harder to control.
Cystic Fibrosis in Children
Nasal polyps are uncommon in children, and when they do appear, they raise concern for cystic fibrosis. Polyps occur in anywhere from 6% to 48% of cystic fibrosis cases, yet only about 4% of patients who present with nasal polyps are actually tested for it. A sweat chloride test is the standard screening method. If sweat chloride levels come back at 60 mmol/L or higher on two separate occasions, cystic fibrosis is confirmed. Genetic testing can also identify the specific mutations involved. Because early treatment of cystic fibrosis significantly improves long-term outcomes, testing matters even when the polyps themselves seem like the only problem.
What the Diagnosis Looks Like in Practice
For most adults, the diagnostic process is straightforward: you describe your symptoms, get a nasal endoscopy in the office that day, and walk out with a confirmed diagnosis within minutes. If your doctor wants a CT scan, that’s usually scheduled separately and takes about 15 minutes. The scan itself is painless and doesn’t involve any injections.
Your doctor will grade the severity of your polyps based on their size and how much they obstruct the nasal passages. Small polyps that don’t fully block airflow are treated differently than large ones that fill the nasal cavity. The combination of what they see on endoscopy and what the CT reveals guides treatment decisions, from nasal steroid sprays for mild cases to biologic medications or surgery for severe or recurrent disease.
If you’ve been dealing with persistent congestion, a reduced sense of smell, or the feeling that your nose is always blocked, these symptoms alone are enough reason to get evaluated. The diagnostic process is quick, minimally uncomfortable, and gives clear answers.