What Can a Sinus CT Show When Nasal Congestion Is Mostly on One Side?

Direct Answer: What Can a Sinus CT Show?

When congestion primarily affects one side, a sinus CT may show:

• A deviated septum narrowing one nasal passage
• Enlarged turbinates
• Thickened sinus tissue or trapped fluid
• Narrowed or obstructed sinus drainage pathways
• Soft-tissue findings consistent with nasal polyps
• Structural differences in the nose and sinuses
• A pattern suggesting dental-related sinus inflammation
• An uncommon abnormality requiring further evaluation

A CT scan cannot always determine the exact cause of an abnormality by itself. The images must be interpreted alongside the patient’s symptoms, medical history, office examination, and nasal endoscopy when performed.

Why Does One Side of the Nose Feel More Blocked?

The nose naturally alternates airflow between the left and right nasal passages. During this process, known as the nasal cycle, tissue inside one side becomes slightly more swollen while the opposite side becomes more open. The pattern generally reverses after several hours.

Most people do not notice the nasal cycle. It may become more apparent during a cold, allergy flare, or period of nasal inflammation.

Persistent obstruction on the same side is different. Potential causes include:

• A deviated septum
• Enlarged turbinates
• Chronic nasal or sinus inflammation
• Nasal polyps or another growth
• Nasal valve collapse
• Changes following an injury or previous surgery
• A foreign object, particularly in a young child
• Less commonly, another abnormality inside the nose or sinuses

The symptom pattern and examination findings help determine whether imaging is likely to provide useful information.

What Is a Sinus CT?

A sinus CT is an imaging examination that uses specialized X-ray equipment and computer processing to create cross-sectional images of the nose and paranasal sinuses.

Unlike a conventional X-ray, CT images can be reviewed in multiple planes. This gives the provider a detailed view of deeper sinus cavities and surrounding bone that cannot be completely evaluated through a routine office examination.

Routine sinus CT imaging is commonly performed without contrast. Contrast, MRI, or another study may be recommended if more information is needed about a mass, complication, blood vessel, or surrounding soft tissue.

Because CT imaging uses ionizing radiation, it should be performed when the expected diagnostic information is likely to affect evaluation or treatment planning.

What Findings May Explain One-Sided Congestion?

Several findings may be relevant when the same side of the nose remains blocked.

A deviated septum

The nasal septum is the wall of cartilage and bone separating the nasal passages. When it bends significantly toward one side, that passage may have less room for airflow.

A CT can show the shape and position of the septum and how it relates to nearby structures. An office examination or nasal endoscopy may also identify a deviation.

Not every deviated septum requires treatment. Many people have some degree of deviation without significant symptoms. The provider must determine whether the finding corresponds with the location and severity of the obstruction.

A deviated septum may contribute to difficulty breathing, but it does not automatically cause chronic sinus disease or recurring infections.

Enlarged turbinates

Turbinates are structures along the sidewalls of the nose that warm, humidify, and filter inhaled air. Their soft tissue naturally expands and contracts throughout the day.

Allergies, irritants, infections, and other inflammation may cause the turbinates to remain enlarged. A CT may show that a turbinate is enlarged or that the available airway is narrow.

Because turbinate swelling can change, an office examination remains important for determining whether the finding matches the symptoms.

Narrowed sinus drainage pathways

The sinuses drain through relatively small openings. Inflammation, structural variations, polyps, or another condition can narrow these pathways and interfere with ventilation or mucus drainage.

A CT can map drainage anatomy that cannot be directly seen during a standard examination. This may be useful when one-sided congestion occurs with facial pressure, persistent drainage, reduced smell, or recurring sinus infections.

Sinus inflammation

CT imaging may show:

• Thickening of the sinus lining
• Fluid inside a sinus cavity
• Partial or complete opacification
• Inflammation concentrated on one side
• Changes around a sinus drainage pathway

These findings may support a diagnosis of sinus disease when they correspond with the patient’s symptoms and examination.

An abnormal CT does not automatically mean that an active bacterial infection is present. Imaging cannot always determine whether inflammation is viral, bacterial, fungal, dental, allergic, or related to another cause. Mild changes may also appear in patients without significant sinus symptoms.

Nasal polyps or another soft-tissue finding

Nasal polyps are noncancerous growths associated with inflammation of the nasal and sinus lining. They may contribute to congestion, reduced smell, postnasal drip, and impaired sinus drainage.

CT imaging may show soft-tissue changes consistent with polyps and help determine how extensively the sinuses are involved. However, a CT cannot always distinguish a routine inflammatory polyp from every other type of soft-tissue abnormality.

Inflammatory polyps commonly affect both sides. A one-sided growth may require closer evaluation with nasal endoscopy, MRI, biopsy, or another test.

Nasal valve narrowing

The nasal valve is the narrowest part of the nasal airway. Weakness or narrowing in this area can reduce airflow, particularly during deep inhalation or exercise.

Nasal valve problems are often evaluated during a physical examination because the sidewall may move inward while the patient breathes. CT imaging may provide information about surrounding anatomy, but it does not replace a functional examination of the valve.

Dental-related sinus inflammation

The roots of the upper teeth are located close to the maxillary sinuses. A dental infection, extraction, implant, or another dental condition may sometimes contribute to inflammation in one maxillary sinus.

A sinus CT may show a pattern that raises concern for a dental source. It does not replace a dental examination or dedicated dental imaging, and further evaluation may be recommended.

An uncommon growth or mass

Most one-sided congestion is not caused by cancer. Nevertheless, persistent unilateral obstruction—particularly when accompanied by recurring bleeding, facial numbness, swelling, or vision changes—requires careful evaluation.

A CT may identify an abnormal soft-tissue area, expansion of a sinus, or changes involving nearby bone. Additional imaging or biopsy may be needed to determine what the finding represents.

Is a CT Always Needed for One-Sided Congestion?

No. A CT scan is not automatically necessary whenever one nostril feels blocked.

An ENT evaluation generally begins with a review of the patient’s symptoms, medical history, previous treatment, and any history of nasal injury or surgery. The provider may examine airflow through each nostril and look for swelling, crusting, drainage, structural narrowing, or another obstruction.

Nasal endoscopy may provide a closer view of deeper areas inside the nasal passages. CT imaging may be considered when:

• The same side remains blocked for several weeks
• Symptoms persist despite appropriate treatment
• Chronic or recurrent sinus disease is suspected
• Nasal endoscopy identifies an abnormality
• Congestion occurs with persistent bloody drainage
• The diagnosis remains unclear
• Detailed anatomy is needed for treatment planning

The goal is not simply to obtain an image. It is to answer a clinical question and determine whether the imaging findings explain the patient’s symptoms.

What Happens After the CT?

The next step depends on the full evaluation rather than the scan alone.

If inflammation is the primary problem, treatment may include an appropriate nasal spray, allergy management, saline treatment, or other medical care. Nasal irrigation should be performed only with distilled, sterile, or previously boiled and cooled water.

If a structural condition significantly restricts airflow, an ENT physician may discuss options such as septoplasty, turbinate reduction, or treatment for nasal valve collapse.

Patients with confirmed chronic sinus disease may be evaluated for medication or an appropriate procedure. Balloon sinus dilation may be considered for selected patients whose symptoms, examination, and imaging show qualifying disease. It is not appropriate for every type of congestion or every CT abnormality.

A CT result does not automatically mean surgery is necessary. It provides one part of the information used to develop an individualized treatment plan. Results and recovery experiences vary.

When Should One-Sided Congestion Be Evaluated?

Consider an evaluation with an ENT in Rancho Cucamonga when:

• The same nostril remains blocked for several weeks
• Congestion interferes with sleep, exercise, or daily activities
• Symptoms persist despite appropriate treatment
• Facial pressure or drainage repeatedly affects one side
• The sense of smell decreases or changes
• Sinus infections recur
• Nasal drainage is bloody, foul-smelling, or consistently one-sided
• Symptoms progressively worsen

Seek prompt medical attention for swelling or redness around the eyes, vision changes, facial numbness or weakness, severe headache, confusion, neck stiffness, significant facial swelling, or rapidly worsening symptoms.

Find Out What Is Behind the Blockage

A sinus CT may help identify structural narrowing, inflammation, blocked drainage pathways, polyps, or another abnormality that could contribute to one-sided nasal congestion. However, imaging is only one part of the evaluation and cannot determine the cause of every finding by itself.

Schedule an appointment with ENT & Sinus Center to discuss persistent one-sided congestion and determine whether an office examination, nasal endoscopy, in-office CT scan, or another approach may be appropriate.