Learning Objectives
Master the clinical recognition of Choanal Atresia. Understand the paradox of cyanosis (worsening with feeding, improving with crying) and memorize the components of CHARGE syndrome for the USMLE Step 1.
1. Pathophysiology and Presentation
Choanal atresia is a congenital blockage of the posterior nasal opening (choanae) into the nasopharynx. It can be bony (90%) or membranous (10%).
| Type | Clinical Presentation |
|---|---|
| Unilateral | Most common. Often asymptomatic until the first respiratory infection, it presents with chronic nasal discharge. |
| Bilateral | Neonatal Emergency. Newborns are obligate nose breathers; this causes immediate respiratory distress. |
2. The Classic “Cyanosis Paradox.”
In bilateral cases, the infant exhibits a very specific respiratory pattern that is a classic board exam “clue.”
| Scenario | Clinical Finding | Mechanism |
|---|---|---|
| Feeding | Cyanosis worsens | The mouth is occupied by the nipple; no airway is available. |
| Crying | Cyanosis improves | The infant breathes through the open mouth while crying. |
3. Diagnosis and CHARGE Syndrome
Initial diagnosis is often made at the bedside when a nasogastric (NG) tube cannot be passed through the nose. Confirmation: Axial CT scan showing narrowing at the level of the pterygoid plates.
Associations: Often occurs as part of the CHARGE mnemonic:
| Letter | Feature |
|---|---|
| C | Coloboma of the eye (key-hole shaped iris) |
| H | Heart defects (e.g., Tetralogy of Fallot) |
| A | Atresia of choanae |
| R | Restricted growth and development |
| G | Genitourinary defects |
| E | Ear defects (deafness/abnormal shape) |
Activity:
High-Yield Clinical Pearls:
- The NG Tube Test: In a newborn with respiratory distress, if you can’t pass an NG tube through the nose, Choanal Atresia is the top differential.
- Emergency Management: An oral airway or intubation is required immediately for bilateral cases.
- Coloboma Link: If a vignette mentions a “cleft in the iris” and “noisy breathing,” they are pointing you toward CHARGE syndrome.