1. Definition

Choanal atresia is a congenital failure of the posterior nasal aperture (choana) to open, resulting in complete or partial obstruction between:

Nasal cavity anteriorly
Nasopharynx posteriorly

It may involve:

Bone
Membrane
A combination of both

Because newborns are obligate nasal breathers, bilateral choanal atresia is a life-threatening neonatal emergency.

2. Embryology (Ultra-Expanded ENT Detail)

Choanal development occurs around 4–10 weeks of gestation.

Normal embryological sequence:

Nasal cavity initially separated from oral cavity by oronasal membrane.
This membrane should rupture by week 6.
Posterior nasal cavity elongates, forming secondary choanae.
Vomer bone grows downward to separate choanae.
Mesodermal migration ensures patency of posterior airway.

Failure of these steps results in choanal atresia:

Persistence of the oronasal membrane
Abnormal mesoderm migration
Overgrowth of posterior vomer
Abnormal integration of buccopharyngeal membrane
Excessive fusion between nasal septum and palatal shelves

Key embryological theories (important for viva):

Persistence of bucconasal membrane theory
– Most widely accepted.
Abnormal migration of neural crest cells
– Explains association with CHARGE syndrome.
Misalignment of medial nasal and maxillary processes
– Explains unilateral disease.

3. Applied Anatomy (Pure ENT Focus)

Understanding anatomy helps ENT surgeons plan endoscopic repair.

Choanae are bordered by:

Medially: Vomer
Inferiorly: Hard palate
Superiorly: Sphenoid sinus
Laterally: Medial pterygoid plate

Atresia Plate Composition:

90% bony (vomer + medial pterygoid plate thickening)
10% membranous

Associated anatomical issues:

Narrow nasal cavity
High arched palate
Midface anomalies
Absent nasal choanal air column on CT

4. Types of Choanal Atresia

A. According to Laterality

Unilateral (60–70%)
Bilateral (30–40%) – emergency

B. According to Composition

Bony atresia (90%)
Membranous atresia (10%)
Mixed type (common clinically)

C. According to Pattern

Right-sided more common than left.

D. According to Condition of Nasal Cavity

Narrow nasal cavity syndrome
Associated with pyriform aperture stenosis

5. Epidemiology

Occurs in 1 in 5000–8000 live births.
Female predominance (2:1).
Bilateral cases present immediately after birth.
Unilateral cases often diagnosed late in childhood.

6. Etiology

Choanal atresia is primarily embryological, but associated conditions contribute:

Genetic Associations

CHARGE syndrome (most important)
Treacher Collins
Crouzon syndrome
Down syndrome

Environmental Factors

Maternal hyperthyroidism
Antithyroid medications
Vitamin A excess (retinoic acid)

Multifactorial Etiology

Combination of genetic + environmental influences.

7. Pathogenesis (ENT Deep Explanation)

The final atretic plate seen in choanal atresia results from:

Failure of canalization of the posterior nasal cavity
Abnormal persistence of the buccopharyngeal (oronasal) membrane
Excessive ossification of the vomer
Fusion between vomer and palatine bone
Failure of resorption of mesoderm between nasal cavity and nasopharynx

Why bony type is more common?

Because:

Vomer is the last midline structure to ossify
Excessive downward growth can close choana
Membranous atresia often secondarily ossifies in utero

8. Neonatal Nasal Breathing Physiology (Pure ENT Style)

Even though this is physiology, ENT examiners expect this ENT-framed explanation.

Newborns are obligate nasal breathers because:

Large tongue relative to oral cavity
High larynx position (C3–C4)
Close apposition of soft palate and epiglottis
Immature oral breathing coordination
Narrow nasal passages already predisposed to obstruction
Feeding requires simultaneous suckling + nasal breathing

Implication:

Any nasal obstruction = respiratory distress
Bilateral choanal atresia → immediate airway failure.

9. Classical Clinical Features (ENT Full Breakdown)

Presentation depends on unilateral vs bilateral.

A. Bilateral Choanal Atresia – Neonatal Emergency

Classic Triad:

Cyclic cyanosis
Cyanosis relieved by crying (because crying forces mouth breathing)
Respiratory distress during feeding

Other Features:

Chest retractions
Apnea episodes
Inability to feed
Snorting, nasal obstruction noises
Inability to pass catheter through nostril
Asphyxia risk

Pathophysiology of Cyclic Cyanosis:

Neonate breathes through nose → obstruction → cyanosis
Crying opens mouth → temporary relief → pinking up
Once quiet → obstruction recurs → cyanosis returns

ENT examiner expects this EXACT articulation.

B. Unilateral Choanal Atresia

Often diagnosed late in childhood.

Symptoms:

Unilateral foul-smelling discharge
Persistent unilateral nasal obstruction
Recurrent sinusitis
Snoring
Mouth breathing

Examination:

Deviated septum towards atretic side
Narrow nasal cavity
Sticky discharge

Written And Compiled By Sir Hunain Zia (AYLOTI), World Record Holder With 154 Total A Grades, 7 Distinctions And 11 World Records For Educate A Change MBBS 4th Year (Fourth Professional) Otorhinolaryngology (ENT) Free Material

10. Physical Examination (ENT OSCE Method)

A structured ENT exam approach.

External Inspection

Mouth breathing
Chest retractions
Cyanosis patterns
Dysmorphic features (CHARGE)

Anterior Rhinoscopy

Narrow nasal passages
Mucus pooling
Medially displaced septum

Attempt Passing a No. 6 French Catheter

Failure at 3–4 cm from nostril strongly suggests CA
Must attempt BOTH sides

Fogging Test

Hold mirror under nostrils – unilateral or absent fogging.

Indirect Nasopharyngoscopy (if stable)

May show a membrane or bony plate posteriorly.

11. Investigations (Ultra-Expanded ENT Radiology)

A. Cotton-Wool Test

Place cotton near nostril → no movement on inspiration.
Not reliable in neonates.

B. Pass a Nasogastric Tube

Most practical bedside ENT test.

Cannot pass into esophagus = strong suspicion
If unilateral, other side may pass easily

C. CT Scan of Nose and Paranasal Sinuses (Gold Standard)

ENT radiology examiners expect text-based interpretation:

CT Findings:

Thickened bony atretic plate
Obliteration of posterior choana
High posterior vomer
Narrow nasal cavity
Medial bowing of lateral nasal wall
Soft tissue/membrane density in membranous type
Rule out:
- Pyriform aperture stenosis
- Skull base defects

CT Planes:

Axial → shows bony plate
Coronal → best for vomer thickness
3D reconstruction → surgical planning

D. MRI

Used when:

Suspecting associated midline anomalies
Child has syndromic features

12. Differential Diagnosis of Neonatal Nasal Obstruction

ENT students MUST know this list:

Condition	Key Clue
Bilateral choanal atresia	Cyclic cyanosis relieved by crying
Pyriform aperture stenosis	Narrow anterior bony inlet
Septal deviation/dislocation	History of birth trauma
Nasal cyst/mass	Visible swelling
Encephalocoele	Expands on crying
Dermoid cyst	Midline pit, hair
Neonatal rhinitis	Mucosal edema
Nasal foreign body	Older children, not neonates

13. CHARGE SYNDROME – ENT RELEVANCE

Choanal atresia is most strongly associated with CHARGE syndrome, and ENT examiners expect students to recite this entire acronym verbatim.

CHARGE =

C – Coloboma of eye
H – Heart defects
A – Atresia of choanae
R – Retarded growth and development
G – Genital hypoplasia
E – Ear anomalies / hearing loss

Why ENT must recognize this syndrome:

Choanal atresia may be the earliest presenting feature.
Abnormal ear anatomy → difficult intubation.
Hearing loss → early audiology referral needed.
Cranial nerve abnormalities → poor feeding, aspiration.
Important for neonatal airway planning.

ENT physical features in CHARGE:

External ear deformity (“lop ear”)
Facial palsy
Choanal stenosis or atresia
Middle ear effusion
Cranial nerve dysfunction (IX, X)

Implications for choanal atresia surgery:

Higher rate of restenosis
Poor wound healing
Greater anesthesia risk

14. Management of Choanal Atresia – ENT Surgical Principles

Management depends on whether obstruction is bilateral (emergency) or unilateral (elective).

A. Bilateral Choanal Atresia – EMERGENCY MANAGEMENT

Immediate Stabilization (Lifesaving ENT Steps)

Maintain airway
- Start with oropharyngeal airway
- Insert McGovern nipple (airway device with large hole allowing oral breathing)
Oxygenation
- Blow-by oxygen
Orogastric or orotracheal intubation if needed
Avoid nasal airways, as they will not pass

Why oral airway works:

Crying + oral devices bypass nasal obstruction and allow adequate ventilation.

Definitive Management After Stabilization

Once stable, baby undergoes endoscopic repair within first few days/weeks of life.

B. Unilateral Choanal Atresia – ELECTIVE MANAGEMENT

Child may present years later
Repair usually delayed until 4–6 years of age
Symptomatic children operated earlier

15. Surgical Approaches (ENT Ultra-Detailed)

ENT surgeons must know three classical approaches and why endoscopic is preferred.

15.1 Transnasal Endoscopic Approach (Gold Standard)

Modern ENT standard.
Advantages:

Minimally invasive
Excellent visualization
Precise removal of atretic plate
Preservation of mucosa
Lower morbidity
Shorter hospital stay

Steps (Detailed):

Insert pediatric rigid nasal endoscope (0° / 2.7 mm).
Identify atretic plate.
Remove membranous/bony obstruction using microdebrider, drill, or punch.
Widen posterior choana.
Remove posterior vomer (key step to prevent restenosis).
Preserve mucosa to line neo-choanae.

Important ENT Principle:

Resection of posterior vomer drastically lowers recurrence.

Stenting – Should you use it?

Controversial
Some surgeons place a stent for 4–6 weeks
Others avoid stents to reduce granulation
CHARGE patients have higher restenosis → stents may help

15.2 Transpalatal Approach (Historical / Rare Today)

Used before modern endoscopes became standard.

Procedure:

Incision on palate
Elevation of mucoperiosteal flap
Remove bony atresia from behind
Reconstruct palate

Disadvantages:

Large blood loss
Palatal dysfunction
Feeding difficulty
Speech problems
Long healing time

Why ENT no longer prefers it:

Endoscopic method superior
High morbidity

15.3 Transseptal Approach (Less Common)

Used for older children or combined deformities
Requires septal cartilage removal
Preserves mucosa if done correctly

Problems:

Risk of septal perforation
Cosmetic deformity if growth centers disturbed

16. Post-Operative Care (ENT Intensive Detail)

1. Airway Monitoring

Monitor for obstruction
Suction secretions gently
Maintain humidified oxygen

2. Stent Care (if used)

Regular saline suctioning
Prevent crusting
Risk of granulation if poorly maintained

3. Antibiotics

Prevent infection
Minimize granulation

4. Nasal Douching

Started once mucosa heals
Prevents crust formation

5. Follow-Up Endoscopy

Essential every 1–2 weeks initially
Early detection of restenosis

6. Management of Restenosis

Balloon dilation
Revision endoscopic surgery
Mitomycin-C (controversial, used to reduce fibrosis)

17. Complications of Choanal Atresia & Surgery

A. Before Surgery

Severe neonatal hypoxia
Aspiration
Failure to thrive
Apneic episodes
Feeding difficulty
Recurrent pneumonia

B. During Repair

Bleeding
Injury to skull base → CSF leak
Damage to eustachian tube opening
Septal injury
Turbinate trauma

C. After Surgery

Restenosis (most common)
Infection
Synechiae formation
Stent-related complications (pressure necrosis)
Persistent nasal obstruction

18. Prognosis

Unilateral CA: Excellent prognosis
Bilateral CA: Depends on early recognition and airway management
CHARGE syndrome increases surgical difficulty and recurrence

19. Detailed ENT Viva Questions & Answers

Q1: What is the most common type of choanal atresia?

A: Mixed bony + membranous; predominantly bony.

Q2: Why do neonates with bilateral CA develop cyclic cyanosis?

A: They are obligate nasal breathers; crying forces mouth breathing → temporary relief.

Q3: What is the gold-standard investigation?

A: CT scan of nose & paranasal sinuses.

Q4: Why is endoscopic repair preferred?

A: Minimally invasive, precise, preserves mucosa, lower morbidity.

Q5: What happens if you do not remove the posterior vomer?

A: Recurrence due to restenosis.

Q6: What syndrome is most strongly associated?

A: CHARGE syndrome.

Q7: What is the first step in managing bilateral CA in a newborn?

A: Secure airway via oropharyngeal airway or McGovern nipple.

Q8: What are signs of unilateral CA in older children?

A: Unilateral discharge, foul smell, nasal obstruction, sinusitis.

20. High-Yield Comparison Table: Unilateral vs Bilateral CA

Feature	Unilateral	Bilateral
Age at presentation	Childhood	Neonate
Symptoms	Discharge, obstruction	Cyanosis, apnea
Emergency?	No	Yes
Feeding difficulty	Mild	Severe
Cyclic cyanosis	No	Yes
Surgery timing	Elective	Urgent

21. Pathophysiology of Nasal Airflow in Neonates (ENT Style)

Though this is physiology, ENT surgeons must explain it clearly.

Key Reasons Neonates Depend on Nasal Breathing:

Coordination of suck-swallow-breathe requires nasal patency
Oral cavity too small for concurrent airflow
High larynx allows epiglottis to touch soft palate → separates airway during feeding
Mouth breathing reflex matures late

Therefore:

Bilateral CA = incompatible with feeding without airway support.

22. Summary of What the Examiner Wants (Pure ENT)

Clear embryology
Emergency nature of bilateral CA
Cyclic cyanosis mechanism
CT scan as gold standard
Endoscopic repair as gold standard
Stenting controversy
CHARGE association
Posterior vomer removal preventing restenosis
Differential diagnosis of neonatal obstruction