A deviated septum is diagnosed through a physical exam of the inside of your nose, typically performed by an ENT (ear, nose, and throat) specialist. The exam takes only a few minutes and usually involves a bright light, a tool to gently widen your nostrils, and sometimes a thin flexible scope to see deeper into the nasal cavity. Imaging like a CT scan is rarely needed for a straightforward case.
What Happens During the Exam
The core of the diagnosis is a visual inspection called anterior rhinoscopy. Your doctor uses a bright light and a small instrument called a nasal speculum to spread your nostrils open, giving them a clear view of the cartilage wall (the septum) that divides your nasal passages. They’re looking for curves, bends, or bony spurs that push the septum to one side, narrowing the airway.
If your doctor needs to see further back, they’ll use a nasal endoscope: a thin, flexible tube with a camera and light at the tip. This is threaded gently into your nostril and lets them examine the full length of your nasal cavity and the openings to your sinuses. Before the endoscope goes in, a topical numbing spray is applied so you feel pressure but not pain. The whole process typically takes less than a minute per side.
During the exam, your doctor will also check for other things that can block your breathing: swollen turbinates (the ridges along the inner wall of your nose), nasal polyps, tumors, or signs of chronic sinus inflammation. This matters because a deviated septum often coexists with these conditions, and treating the deviation alone won’t help if something else is also contributing.
The Decongestant Test
One key question your doctor needs to answer is whether your obstruction is “fixed” or “reversible.” A deviated septum is a structural problem, meaning it doesn’t change with medication. Swollen tissue, on the other hand, shrinks when treated. To tell the difference, your doctor may spray a topical decongestant into your nose and then re-examine you after a few minutes. If the blockage clears up, swelling is the main culprit. If it stays, a structural issue like a deviated septum is more likely responsible.
The Cottle Maneuver
Your doctor may also perform a simple physical test called the Cottle maneuver, which helps distinguish a deviated septum from nasal valve collapse, a condition where the sidewall of the nostril is weak and collapses inward when you breathe in. During the maneuver, your doctor gently pulls your cheek to the side, widening the nostril opening. If your breathing dramatically improves, the problem is more likely a weak nasal valve rather than (or in addition to) a septal deviation. Sometimes a cotton swab or small instrument is used inside the nostril for a more targeted version of the test.
When CT Scans Are Needed
For a simple deviated septum, imaging is unnecessary. The diagnosis is clinical, meaning your doctor can see and confirm it during the physical exam. CT scans enter the picture in more complex situations: when sinus disease is suspected, when the deviation is so severe that the endoscope can’t get past it to see the back of the nasal cavity, or when surgery is being planned and the surgeon needs a detailed map of the anatomy.
A CT scan can also reveal related problems that contribute to your symptoms, such as a concha bullosa (an air-filled pocket inside a turbinate bone) or chronic sinusitis. But because CT scans involve radiation exposure and added cost, guidelines recommend reserving them for cases where the physical exam alone doesn’t tell the full story.
Airflow Testing
In some cases, particularly when symptoms don’t clearly match what the doctor sees on exam, a test called rhinomanometry can objectively measure how well air flows through each side of your nose. The test works by measuring the air pressure and flow rate as you breathe through your nostrils, one side at a time. It quantifies the resistance your nasal passages create, giving your doctor a number to work with rather than relying solely on your subjective sense of blockage. This test isn’t routine for most patients but can be useful when there’s a disconnect between how obstructed your nose looks and how obstructed it feels.
How Severity Is Assessed
Not all deviations are the same. The septum can bend at different points, in different directions, and with varying degrees of severity. Classification systems describe at least six distinct patterns of deviation, ranging from a simple bony spur along the floor of the nose to a cartilage bend high up in the nasal cavity to a combination of curves that twist the septum into an S-shape. Your doctor won’t necessarily name the “type” you have, but they’ll note where the deviation is, how severe it is, and whether it’s causing a functional problem.
Here’s an important point: the vast majority of people have some degree of septal deviation. One study using cone-beam CT scans found that nearly 88% of people had a measurable deviation. Most of these cause zero symptoms. A deviated septum only becomes a medical concern when it’s severe enough to block airflow, cause recurrent nosebleeds, contribute to chronic sinus infections, or create facial pain from the septum pressing against the side wall of the nose.
What Makes It a Diagnosis Worth Treating
The American Academy of Otolaryngology outlines several scenarios where a deviated septum warrants intervention:
- Chronic nasal obstruction that hasn’t improved with medical treatment like nasal steroid sprays
- Frequent nosebleeds that don’t respond to standard management, where the deviation is the identifiable cause
- Facial pain of nasal origin, particularly when a numbing spray applied to the point where the septum contacts the side wall relieves the pain
- Access for other procedures, where the deviation physically blocks the path to the sinuses or other structures that need surgical treatment
Your doctor is required to document a complete intranasal exam before recommending surgery, including noting whether polyps, turbinate enlargement, nasal valve issues, or other causes of obstruction are present. This is partly to confirm the septum is actually the problem and partly because fixing additional issues at the same time leads to better outcomes.
You may also be asked to fill out a symptom questionnaire called the NOSE (Nasal Obstruction Symptom Evaluation) scale, which ranks your breathing difficulty from mild to extreme. This gives your doctor a baseline score to compare against if you eventually have surgery, and helps quantify something that’s otherwise hard to measure objectively.