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

Nasal congestion that consistently affects one side can feel as though something is physically blocking the nose. The cause may be as straightforward as a deviated septum or swollen turbinate, but persistent one-sided symptoms may also require evaluation for inflammation, a dental problem, nasal polyps, or another condition.

An office examination is usually the first step. If additional information is needed, an ENT care provider may recommend a sinus CT scan to evaluate structures that cannot be seen completely during a routine examination.

At Tampa Bay Breathe Free, the clinical team helps patients in St. Petersburg, Bradenton, and the greater Tampa Bay area understand what may be contributing to one-sided nasal congestion and whether additional testing may be appropriate.

Direct Answer: What Can a Sinus CT Show?

A sinus CT can show whether one side of the nasal or sinus anatomy is narrower or more inflamed than the other. It may identify a deviated septum, enlarged turbinates, blocked sinus drainage pathways, thickened sinus tissue, trapped fluid, or an abnormal area requiring further evaluation.

The scan cannot always determine the exact cause of an abnormality by itself. Its findings must be interpreted together with the patient’s symptoms, examination, and medical history.

What Is a Sinus CT Scan?

A computed tomography, or CT, scan is an imaging examination that uses specialized X-ray equipment and computer processing to create cross-sectional images of the body.

A sinus CT scan produces detailed images of the nasal passages, paranasal sinuses, drainage pathways, and surrounding bony anatomy. The images can be reviewed in multiple planes, providing more information than a conventional X-ray.

Sinus CT imaging may be used to:

• Evaluate persistent or recurring sinus symptoms
• Look for fluid or thickened sinus tissue
• Identify narrowed or obstructed drainage pathways
• Assess structural differences
• Evaluate the extent of inflammatory sinus disease
• Provide information for treatment or procedure planning
• Investigate an unexpected or concerning examination finding

Routine sinus CT scans are commonly performed without contrast. Contrast or another imaging study may be recommended when a provider needs more information about a mass, complication, blood vessel, or surrounding soft tissue.

What Happens During a Sinus CT?

The process depends on the imaging equipment being used. With a conventional CT scanner, the patient generally lies on a table that moves through a circular opening while images are captured from several angles.

Some ENT offices use specialized scanners that allow the patient to sit or stand. The imaging portion is generally brief and noninvasive, although the complete appointment time varies.

Patients should remain still while the images are taken. They should also tell the provider if they may be pregnant, have undergone recent imaging, or have questions about radiation exposure.

What Might a Sinus CT Show When One Side Is Congested?

One-sided congestion can have several possible causes. A CT scan may provide information about the following findings.

A deviated nasal septum

The nasal septum is the wall of bone and cartilage separating the left and right nasal passages. If it bends significantly toward one side, that passage may be narrower.

A CT scan can show the position of the septum and its relationship to other structures. However, a visible deviation does not automatically mean it is causing the symptoms. The provider must compare the imaging with the side of the blockage and the physical examination.

A deviated septum may restrict nasal airflow, but it does not necessarily block sinus drainage or cause infections in every patient.

Enlarged turbinates

Turbinates are structures along the sidewalls of the nose that help warm, humidify, and filter inhaled air. The soft tissue covering them can swell in response to allergies, irritants, infections, or other inflammation.

A CT may show asymmetry or enlargement of the turbinates. Turbinate swelling can also change throughout the day, so an office examination remains important for understanding whether the finding corresponds with the patient’s symptoms.

One-sided sinus inflammation

Sinusitis involves inflammation of the tissue lining the sinuses. When inflammation affects primarily one side, a CT may show:

• Thickening of the sinus lining
• Fluid within a sinus cavity
• Partial or complete opacification
• Involvement of one or several sinuses
• Changes around a sinus drainage pathway

These findings do not automatically establish whether the cause is viral, bacterial, fungal, dental, or inflammatory. Mild imaging changes may also occur in people without significant symptoms.

A narrowed sinus drainage pathway

Each sinus drains through a relatively small opening. Inflammation, anatomy, polyps, or another condition can narrow these pathways and interfere with ventilation or mucus drainage.

A CT can map the deeper drainage anatomy that cannot be completely evaluated during a standard office examination. This information may be useful when chronic sinusitis is suspected or a procedure is being considered.

The ostiomeatal complex is one of the important drainage regions on each side of the nose. Rather than being a single canal, it is an anatomical area through which the frontal, maxillary, and anterior ethmoid sinuses drain. CT imaging may show narrowing or obstruction in this region.

Nasal polyps or other soft-tissue findings

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

A CT scan may show soft-tissue changes consistent with polyps and help determine how extensively the sinuses are involved. However, CT imaging cannot always distinguish a polyp from every other type of soft-tissue abnormality. Nasal endoscopy, MRI, biopsy, or another evaluation may be needed when a finding is unusual or limited to one side.

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 occasionally contribute to inflammation in the nearby sinus.

A CT may show findings that suggest a possible dental source, particularly when inflammation is concentrated in one maxillary sinus. It does not replace a dental examination or dedicated dental imaging. A dental evaluation may be recommended when the pattern raises concern for an odontogenic—or dental—cause.

Fungal material

Certain fungal sinus conditions can affect one sinus and produce characteristic areas of increased density on CT imaging. Imaging may raise suspicion for a fungal process, but additional clinical evaluation is required to establish the diagnosis and determine the appropriate treatment.

An abnormal growth or mass

Most one-sided congestion is not caused by cancer. However, persistent unilateral symptoms—especially when accompanied by recurrent bleeding, facial numbness, swelling, or vision changes—should be evaluated.

A CT may identify an abnormal soft-tissue area, expansion of a sinus, or changes involving nearby bone. It may not determine exactly what the abnormality represents. Nasal endoscopy, MRI, or biopsy may be recommended for further evaluation.

What Can an Office Examination Show?

A sinus CT complements an office examination; it does not replace one.

An office evaluation allows the provider to:

• Review the symptom pattern and medical history
• Compare airflow through each nostril
• Examine visible nasal tissue
• Look for swelling, crusting, bleeding, or drainage
• Identify visible polyps or another obstruction
• Evaluate the ears, mouth, and throat
• Perform nasal endoscopy when appropriate

Nasal endoscopy provides a real-time view of accessible areas inside the nose. CT imaging provides a broader map of the deeper sinus cavities and bony anatomy. Using these findings together may help the provider determine whether an imaging abnormality is relevant to the patient’s symptoms.

Does Everyone With One-Sided Congestion Need a CT?

No. Temporary one-sided stuffiness can occur during a cold, an allergy flare, or the normal nasal cycle. CT imaging is not routinely needed for every episode of nasal congestion.

A provider may consider a sinus CT when:

• The same side remains congested for several weeks
• Symptoms persist despite appropriate treatment
• Chronic or recurrent sinusitis is suspected
• Nasal endoscopy or examination identifies an abnormality
• There is persistent bloody drainage
• Symptoms are unusual, severe, or progressively worsening
• Detailed anatomy is needed for treatment planning

A recurrent acute sinusitis diagnosis generally refers to four or more distinct episodes in one year, with symptoms resolving between episodes. Having several periods of congestion does not automatically meet that definition.

CT imaging uses ionizing radiation, so the expected diagnostic value should outweigh the potential risk. Previous imaging and alternatives may also be considered before a scan is ordered.

When Should One-Sided Congestion Be Evaluated?

Consider scheduling an ENT evaluation when:

• The same nostril remains blocked
• Symptoms continue for several weeks
• Congestion interferes with sleep, breathing, or exercise
• Facial pressure repeatedly affects one side
• Your sense of smell has changed
• Sinus infections keep returning
• Nasal drainage is bloody, foul-smelling, or consistently one-sided
• Symptoms do not improve with appropriate care

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

Understanding One-Sided Congestion

A sinus CT can help identify structural narrowing, inflammation, blocked drainage pathways, or another abnormality that may contribute to one-sided congestion. However, the scan is only one part of the diagnostic process and does not determine the cause of every finding by itself.

Tampa Bay Breathe Free provides ear, nose, and throat care in St. Petersburg, Bradenton, and the greater Tampa Bay area. Contact the team to discuss persistent one-sided nasal congestion and whether an office examination, nasal endoscopy, imaging, or another form of evaluation may be appropriate.