Postoperative Sinonasal CT:

Core objective

In the postoperative patient, the radiologist should answer four practical questions:

1. What operation was actually performed?
2. Are the surgically created drainage pathways patent?
3. Why does disease persist or recur?
4. Is there an urgent surgical complication or a hazard for revision surgery?

The postoperative CT report should function as a revision-surgery roadmap, not merely describe mucosal thickening. This requires mapping residual anatomy, surgically altered anatomy, scar-related obstruction, recurrent inflammatory disease, and the skull-base, orbital, optic, carotid, and arterial boundaries that remain at risk.^{[1][2][^3]}

Before interpretation

Establish the clinical setting

Postoperative findings have different significance depending on the timing and indication for imaging. The report should incorporate, when available:

• Date and type of surgery.
• Operated side and intended extent.
• Indication: inflammatory disease, polyposis, fungal disease, mucocele, CSF-leak repair, tumor, skull-base approach, orbital decompression, or dental disease.
• Immediate symptoms: visual loss, diplopia, proptosis, severe headache, clear rhinorrhea, hemorrhage, fever, neurologic change, or facial swelling.
• Delayed symptoms: persistent obstruction, purulence, facial pressure, recurrent infection, anosmia, or failure of topical therapy.
• Operative note, prior CT/MRI, and pathology.

Comparison with the preoperative study and operative report is particularly important because the same named procedure may produce different anatomic results. Recent literature distinguishes operative extent—what the surgeon intended or documented—from surgical completeness—what anatomy is actually present on postoperative CT.^[4][5]

Use the correct study

Routine early CT is not generally required after uncomplicated ESS. Early imaging is driven by suspected complications, while later imaging is used for recurrent symptoms, inaccessible anatomy, revision planning, or tumor surveillance; endoscopy remains essential for mucosal healing, crusts, and easily visible stenosis.^{[1][14][^15]}

Expected postoperative findings

Early period

During the first days to weeks, expected findings may include:

• Blood products, fluid, secretions, crusts, and edematous mucosa in the operative cavities.
• Partial sinus opacification despite technically patent bony openings.
• Absorbable packing, nonabsorbable packing, spacers, splints, stents, hemostatic material, or steroid-eluting implants.
• Small amounts of nonprogressive nasal or preseptal soft-tissue edema.
• Bony defects representing planned uncinectomy, antrostomy, ethmoidectomy, sphenoidotomy, or frontal drill-out.

Packing and postoperative debris can mimic a mass or persistent disease. Their expected location and evolution should be correlated with the operative note, timing, and prior imaging.^{[16][17][^18]}

Do not overcall routine early opacification as recurrent sinusitis. Conversely, postoperative status should not be used to dismiss a tense orbital collection, expanding hematoma, excessive or increasing pneumocephalus, focal skull-base defect, active extravasation, vascular irregularity, or aggressive extrasinus inflammation.^[19][3]

Intermediate and late period

As healing progresses, the surgeon expects patent, epithelialized cavities that permit ventilation, endoscopic surveillance, irrigation, and topical medication delivery. Important late abnormalities include:

• Ostial or neo-ostial stenosis/atresia.
• Fibrotic webs and synechiae.
• Middle-turbinate lateralization.
• Residual uncinate process.
• Missed natural maxillary ostium with mucus recirculation.
• Residual ethmoid or frontal recess cells.
• Recurrent polyposis or inflammatory mucosal disease.
• Osteitis and neo-osteogenesis.
• Mucocele formation behind an obstructed surgical pathway.
• Persistent fungal material or recurrent tumor.

These findings are major causes of revision surgery and should be linked in the report to the specific obstructed sinus or impaired operative corridor.^{[20][21][^22]}

Reconstruct the operation

Before assessing recurrence, identify the procedure on each side. Avoid the generic phrase “postsurgical changes of FESS.” Instead state which components are present:

• Uncinectomy.
• Middle-meatal antrostomy.
• Anterior ethmoidectomy.
• Posterior ethmoidectomy.
• Sphenoidotomy.
• Frontal sinusotomy and approximate Draf configuration if confidently recognizable.
• Middle- or inferior-turbinate resection/reduction.
• Septoplasty or posterior septectomy.
• Draf III common frontal cavity.
• Medial maxillectomy, mega-antrostomy, or prelacrimal approach.
• Skull-base repair and graft/flap reconstruction.
• Orbital decompression.
• Transsphenoidal or expanded endonasal skull-base approach.

A useful opening statement is:

Bilateral uncinectomies and middle-meatal antrostomies, complete right and partial left ethmoidectomies, bilateral sphenoidotomies, and left frontal sinusotomy. Prior septoplasty and partial middle-turbinate resections.

This immediately tells the ENT surgeon which sinuses were addressed, which may remain unopened, and where landmarks may be absent.

Maxillary sinuses

Confirm the operation

Determine whether an uncinectomy and middle-meatal antrostomy were performed. Describe the antrostomy as patent, narrowed, or obstructed and state whether it is confluent with the natural maxillary ostium. A surgically created opening posterior to—but separate from—the natural ostium creates a potential mucus-recirculation pathway.^{[2][22][^23]}

Look for failure mechanisms

• Residual superior or inferior uncinate process.
• Missed natural ostium.
• Accessory ostium separate from the antrostomy.
• Antrostomy stenosis from scar, recurrent polyps, edema, crust, or osteitis.
• Haller cell or residual infraorbital ethmoid partition narrowing the infundibulum.
• Lateralized middle turbinate narrowing the middle meatus.
• Persistent maxillary disease despite a widely patent antrostomy, which suggests ongoing mucosal, dental, fungal, or systemic inflammatory disease rather than simple mechanical obstruction.
• Retained tooth/root, implant, graft, or other foreign material.
• Odontogenic source: periapical disease, oroantral fistula, extraction defect, implant protrusion, or asymmetric maxillary floor disease.
• Organized hyperattenuating or calcified material suggesting chronic fungal colonization or inspissated secretions.
• Antrochoanal polyp extending through the antrostomy.
• Maxillary mucocele or postoperative maxillary cyst, particularly after prior Caldwell-Luc surgery.

When both the natural ostium and a separate surgical antrostomy remain open, describe their relationship explicitly rather than stating only that an antrostomy is patent. Failure to incorporate the natural ostium is a recognized cause of recirculation and recurrent infection.^[2][22]

What to emphasize

Illustrative reporting example

Wide right middle-meatal antrostomy; however, the natural maxillary ostium remains separate from the antrostomy because of a residual uncinate bridge, creating anatomy that may permit mucus recirculation. Moderate right maxillary mucosal disease persists.

Ethmoid cavity

Determine completeness

Assess the anterior and posterior ethmoid cavities separately. Document residual cells and bony lamellae rather than simply calling the ethmoids “opacified.” Incomplete anterior ethmoidectomy, residual uncinate, middle-turbinate lateralization, incomplete posterior ethmoidectomy, and frontal-recess scarring are common findings in revision candidates.^{[21][22][^5]}

Look specifically for:

• Residual agger nasi, suprabullar, supraorbital ethmoid, Haller, and posterior ethmoid/Onodi cells.
• Retained bulla ethmoidalis or basal lamella partitions.
• Focal isolated opacified cell that could be a persistent reservoir.
• Bony bridges or partitions that block irrigation and endoscopic access.
• Lateralization or destabilization of the middle turbinate.
• Synechiae between the middle turbinate, septum, and lateral nasal wall.
• Recurrent polyposis filling the ethmoid cavity.
• Osteitis/neo-osteogenesis, particularly when narrowing a surgical corridor.

Re-map danger structures

Revision surgery has fewer reliable landmarks. Reassess the skull base, cribriform plate, fovea ethmoidalis, lamina papyracea, anterior and posterior ethmoidal arteries, and any Onodi cell even if they were described before the first surgery. Specifically report new or pre-existing dehiscence, asymmetric skull-base height, exposed orbital fat, and ethmoidal arteries suspended below the skull base.^{[24][25][^2]}

What to emphasize

Illustrative reporting example

Incomplete left anterior ethmoidectomy with residual opacified agger nasi and suprabullar cells obstructing the frontal recess. The left middle turbinate is lateralized against the lamina papyracea, narrowing the superior middle meatus. No skull-base or lamina papyracea defect.

Frontal sinuses

Identify the procedure

Assess each frontal drainage pathway on sagittal and coronal images. Describe a simple frontal sinusotomy, Draf IIa/IIb-type opening, or Draf III common neo-ostium only when confidently supported by the anatomy. For a Draf III, note removal of the superior septum and interfrontal septum, the common cavity, and the dimensions/patency of the neo-ostium when measurable.

Look for failure mechanisms

Frontal recess failure is commonly related to residual frontal recess cells, retained uncinate, lateralized middle turbinate, inflammatory narrowing, scar, recurrent polyposis, or neo-osteogenesis.^{[20][26][^23]}

Report:

• Patency of the frontal recess or frontal neo-ostium.
• Side and level of stenosis.
• Residual agger nasi, supra-agger, suprabullar, frontal, or supraorbital ethmoid cells.
• Fibrotic web across the frontal beak or Draf III cavity.
• Recurrent polyps or mucosal edema.
• Osteitis and circumferential neo-osteogenesis.
• Retained interfrontal partition or asymmetric residual bony shelf.
• Frontal stent position, migration, obstruction, or adjacent inflammatory change.
• Trapped secretions, complete opacification, expansion, or mucocele.
• Orbital roof or anterior skull-base erosion/dehiscence.

Neo-osteogenesis is clinically meaningful when it narrows the neo-ostium; studies demonstrate an inverse relationship between frontal neo-ostial size and the amount of new bone formation.^[27][28]

What to emphasize

Illustrative reporting example

Prior Draf III frontal drill-out. The common frontal neo-ostium is severely narrowed by circumferential neo-osteogenesis and a central fibrotic web, with near-complete bilateral frontal sinus opacification. No expansile mucocele or intracranial extension.

Sphenoid sinuses

Assess surgical access

State whether a sphenoidotomy is present on each side, its approximate patency, and whether residual superior turbinate, sphenoethmoidal recess scarring, polyp, or bony stenosis obstructs access. Distinguish a standard sphenoidotomy from a common sphenoid cavity/posterior septectomy when applicable.

Look for persistent disease

• Unopened or incompletely opened sphenoid sinus.
• Ostial stenosis, scar atresia, recurrent polyps, or persistent edema.
• Residual Onodi cell mistaken for or blocking access to the sphenoid.
• Isolated lateral recess or retromaxillary recess disease.
• Hyperattenuating fungal material.
• Mucocele with expansion or optic canal/cavernous sinus involvement.
• Postoperative skull-base repair materials after transsphenoidal surgery.

Before revision surgery, map the optic nerves, internal carotid arteries, sellar floor, planum, clivus, and sphenoid septa. A residual intersphenoid septum may insert on a carotid canal; report carotid or optic canal protrusion/dehiscence and any newly exposed canal after surgery.^[24][29]

What to emphasize

Illustrative reporting example

Right sphenoidotomy is obstructed by scar and recurrent polypoid tissue, with complete right sphenoid opacification. An Onodi cell courses superolateral to the sphenoid and surrounds the right optic canal. The intersphenoid septum inserts on the left carotid canal.

Nasal cavity and turbinates

Middle turbinates

Describe whether each middle turbinate is intact, partially resected, destabilized, lateralized, or adherent. Lateralization against the lateral nasal wall can obstruct the frontal recess, middle meatus, and maxillary antrostomy; medial synechiae to the septum may be intentional in some cases and should not automatically be called pathologic.^[26][30]

Inferior turbinates

Describe prior reduction or resection, residual hypertrophy, asymmetric mucosal enlargement, and synechiae. Marked turbinate loss and a very capacious nasal airway can support the history of prior aggressive surgery, but empty nose syndrome is a clinical diagnosis and should not be diagnosed on CT alone.^[31][32]

Other nasal findings

Report:

• Synechiae and the exact structures connected.
• Obstruction of the common nasal airway or operative corridor.
• Crusting or debris if conspicuous, while recognizing endoscopy is superior.
• Recurrent polyps and their sinus of origin if discernible.
• Nasal valve narrowing when visible.
• Stents, splints, retained packing, or foreign bodies and associated complications.
• Nasolacrimal duct injury/stenosis when clinically relevant.

What to emphasize

Illustrative reporting example

The right middle turbinate is lateralized and adherent to the lateral nasal wall, obstructing the middle meatus and narrowing both the frontal recess and maxillary antrostomy. Broad left septal-to-inferior-turbinate synechia narrows the left nasal airway.

Septum

Document prior septoplasty, posterior septectomy, residual or recurrent deviation, spurs that restrict endoscopic access, and septal perforation. In the acute setting, look for septal hematoma/abscess, which appears as septal soft-tissue expansion or a rim-enhancing collection and can threaten cartilage viability.^[33][34]

Also assess:

• Persistent deviation limiting the frontal, ethmoid, or sphenoid operative corridor.
• Perforation size and location when measurable.
• Septal-to-turbinate or septal-to-lateral-wall synechiae.
• Loss of cartilaginous support, dorsal collapse, or saddle-nose deformity.
• Posterior septectomy patency after Draf III or transsphenoidal surgery.
• Septal flap donor-site change and reconstructive flap position when relevant.

What to emphasize

Illustrative reporting example

Residual high rightward septal deviation narrows the right middle meatus and frontal operative corridor. A 9-mm anterior cartilaginous septal perforation is present. No septal hematoma or abscess.

Recurrent inflammatory disease

Describe disease distribution and mechanism, not merely severity:

• Which sinuses and operative cavities are involved.
• Partial versus complete opacification.
• Mucosal thickening, fluid level, hyperattenuating material, polypoid tissue, or discrete mass.
• Whether the drainage pathway is patent or obstructed.
• Whether disease lies behind residual cells, scar, or neo-osteogenesis.
• Whether disease persists despite a widely patent pathway.
• Bone change: chronic osteitis/hyperostosis versus smooth expansion versus aggressive destruction.
• Extrasinus spread.

The Lund-Mackay score may document overall burden but does not replace a mechanistic postoperative description. For revision planning, the surgeon needs to know exactly where the obstruction is and what causes it.^[35][36]

Urgent complications

Orbital injury

Immediately communicate:

• Retrobulbar or subperiosteal hematoma.
• Proptosis, optic-nerve stretch, globe tenting, or posterior globe deformation.
• Orbital emphysema when extensive or associated with compartment findings.
• Lamina papyracea defect with herniated orbital fat.
• Medial rectus or other extraocular muscle transection, entrapment, displacement, hematoma, or denervation change.
• Optic canal injury or optic nerve abnormality.
• Orbital cellulitis, subperiosteal abscess, or orbital abscess.
• Cavernous sinus or superior ophthalmic vein thrombosis.

Orbital hematoma with compartment physiology is a vision-threatening emergency; imaging should not delay clinical decompression when the diagnosis is evident.^{[10][3][^37]}

Skull-base and intracranial injury

Look for:

• Cribriform plate, fovea ethmoidalis, frontal recess, planum, or sphenoid roof defect.
• Pneumocephalus, particularly increasing, tension, or remote from expected surgical air.
• CSF-density sinus contents adjacent to a defect.
• Meningocele or meningoencephalocele.
• Intracranial hemorrhage, contusion, cerebritis, meningitis, subdural empyema, or brain abscess.

High-resolution CT best depicts the osseous defect; MRI better evaluates encephalocele, meningitis, cerebritis, abscess, and other soft-tissue complications.^[19][8]

Vascular injury

Suspect vascular injury with severe epistaxis, falling hemoglobin, expanding hematoma, neurologic deficit, or delayed sentinel bleeding. Assess for:

• Active arterial extravasation.
• Pseudoaneurysm.
• Internal carotid injury, dissection, occlusion, or carotid-cavernous fistula.
• Anterior/posterior ethmoidal artery injury.
• Sphenopalatine artery injury.
• Intracranial arterial injury or infarction.

CTA is appropriate for rapid assessment, but catheter angiography is required when endovascular diagnosis and treatment may be needed.^[10][6]

Infection and hemorrhage

Differentiate expected early edema and secretions from rim-enhancing abscess, progressive fat stranding, fascial spread, osteomyelitis, orbital extension, or intracranial infection. Report the size and compartment of any hematoma, active bleeding, airway effect, and relationship to packing or surgical material.^[7][3]

Mucoceles and trapped compartments

A postoperative mucocele results from obstruction of a sinus or residual cell and may develop long after surgery. Look for complete opacification with smooth expansion, thinning or erosion of walls, and orbital or intracranial displacement; MRI is useful when the contents are atypical or extension is uncertain.^[38][6]

The report should name the trapped compartment—for example, lateral frontal sinus, supraorbital ethmoid cell, isolated posterior ethmoid/Onodi cell, or sphenoid lateral recess—and identify the obstructing scar, bony shelf, or neo-osteogenesis if visible.

Postoperative tumors

For tumor or inverted-papilloma follow-up, do not apply a routine inflammatory-sinus template alone. Compare with the pretreatment tumor and postoperative baseline, scrutinizing the operative bed, reconstruction margins, skull base, orbit, pterygopalatine fossa, infratemporal fossa, foramina, cranial nerves, and neck.^[11][12]

Features concerning for recurrence include a new or enlarging nodular/infiltrative enhancing mass, diffusion restriction, new bone destruction, perineural spread, or progressive deep-space infiltration. Scar and granulation tissue can enhance; serial retraction and increasing T2 hypointensity support fibrosis, while progressive masslike tissue and restriction favor recurrence.^[39][40]

Revision danger map

Even if previously reported, provide a fresh surgical safety map because prior surgery can remove normal landmarks:

• C — Cribriform and skull base: height, asymmetry, defects, prior repair, encephalocele.
• L — Lamina papyracea: integrity, dehiscence, orbital-fat prolapse, medial rectus proximity.
• O — Onodi/posterior ethmoid cells: relationship to optic nerve and sphenoid.
• S — Sphenoid and skull base: carotid/optic protrusion or dehiscence, septal insertions, lateral recesses.
• E — Ethmoidal arteries: low-hanging or dehiscent canals, especially with supraorbital cells.

Add structures particularly relevant after surgery: residual uncinate, natural maxillary ostium, antrostomy, middle turbinate, residual ethmoid partitions, frontal neo-ostium, synechiae, neo-osteogenesis, and posterior septectomy.^[25][2]

Suggested report structure

Illustrative report supplied with the source; adapt to the actual examination. These findings are not patient data.

Technique

Noncontrast CT of the paranasal sinuses with thin-section axial acquisition and multiplanar bone and soft-tissue reformations. Navigation protocol performed.

Findings

Prior procedures

Bilateral uncinectomies and middle-meatal antrostomies, right complete and left partial ethmoidectomies, bilateral sphenoidotomies, Draf III frontal sinusotomy, posterior septectomy, and prior septoplasty.

Drainage pathways and disease

Right maxillary antrostomy is widely patent and incorporates the natural ostium. The left natural maxillary ostium remains separate from a narrowed surgical antrostomy because of a residual uncinate bridge, with possible recirculation anatomy. Residual left anterior ethmoid and agger nasi cells obstruct the left frontal recess. The Draf III neo-ostium is moderately narrowed by circumferential neo-osteogenesis. Right sphenoidotomy is patent; left sphenoidotomy is obstructed by scar. Describe disease burden in each sinus.

Nasal cavity

Left middle turbinate is lateralized and adherent to the lateral nasal wall. Residual high septal deviation narrows the left operative corridor. No septal hematoma or abscess.

Critical anatomy/complications

No skull-base or lamina papyracea defect. No orbital or intracranial complication. Onodi cell surrounds the left optic canal. Intersphenoid septum inserts on the right carotid canal.

Impression

Prioritize actionable mechanisms:

1. Obstructed left frontal drainage pathway due to residual agger nasi/anterior ethmoid cells and middle-turbinate lateralization, with complete left frontal sinus opacification.
2. Narrowed left maxillary antrostomy separate from the natural ostium because of residual uncinate tissue, creating potential mucus-recirculation anatomy.
3. Obstructed left sphenoidotomy due to scar, with persistent sphenoid inflammatory disease.
4. Revision hazards: left Onodi cell encasing the optic canal and intersphenoid septal insertion on the right carotid canal. No orbital or skull-base complication.

Quick reference

Global review

• Identify exactly what surgery was performed on each side.
• Compare with the operative note and preoperative CT.
• Report patency, obstruction, and cause for every operated drainage pathway.
• Separate expected early edema/debris from a true complication.
• Re-map skull base, orbit, optic nerve, carotid artery, and ethmoidal arteries for revision surgery.

Maxillary

• Is the antrostomy patent?
• Does it incorporate the natural ostium?
• Look for residual uncinate, separate accessory opening, recirculation, Haller cell, dental disease, foreign material, fungal material, or mucocele.

Ethmoid

• State whether anterior/posterior ethmoidectomy is complete.
• Name residual cells and bony partitions.
• Look for middle-turbinate lateralization, synechiae, polyps, osteitis, and isolated opacified cells.
• Recheck skull base, lamina papyracea, ethmoidal arteries, and Onodi cells.

Frontal

• Identify the frontal procedure and assess recess/neo-ostium patency.
• Look for residual frontal recess cells, scar, fibrotic web, polyps, and neo-osteogenesis.
• Report trapped compartments, mucocele, stent position, and skull-base/orbital-roof defects.

Sphenoid

• Is each sphenoidotomy patent or scarred closed?
• Look for residual Onodi cell, isolated recess disease, fungal material, or mucocele.
• Map optic and carotid canals, intersphenoid septal insertions, sellar floor, planum, and clivus.

Nasal cavity

• Describe middle-turbinate position and resection.
• Name synechiae and the structures they connect.
• Note turbinate overresection, but do not diagnose empty nose syndrome from CT alone.
• Report recurrent polyps, obstructing crust/debris, and retained or displaced implants.

Septum

• Report residual deviation or spur that limits surgical access.
• Look for perforation, hematoma/abscess, synechiae, support loss, and posterior septectomy patency.

Urgent findings

• Orbit: hematoma/compartment syndrome, muscle injury, optic injury, abscess.
• Skull base: defect, CSF leak, pneumocephalus, encephalocele, intracranial infection.
• Vascular: active bleeding, pseudoaneurysm, carotid or ethmoidal arterial injury.
• Urgent or unexpected findings should be communicated directly to the treating surgeon.

Best impression style

• Lead with the mechanism of failure, not “chronic pansinusitis.”
• Link each obstructing structure to the affected sinus.
• State revision hazards explicitly.
• Mention absence of orbital/skull-base complication when that is the clinical question.
• Keep incidental mild mucosal thickening subordinate to surgically actionable findings.