What's the differential diagnosis for a 3-week-old baby with nasal congestion?

Differential Diagnosis for Nasal Congestion in a 3-Week-Old Infant

In a 3-week-old infant with nasal congestion, your differential should prioritize life-threatening conditions first, as neonates are obligate nasal breathers and even minor obstruction can be fatal. 1

Critical Anatomic Causes (Rule Out First)

Congenital choanal atresia is the most critical diagnosis to exclude, as it causes reduced airflow through nasal passages and can lead to fatal airway obstruction in neonates who cannot mouth-breathe effectively. 1

• Nasal passages contribute 50% of total airway resistance in newborns, meaning any obstruction creates near-total blockage and potential respiratory failure. 1
• Complete or partial nasal obstruction in infants below 2-6 months can lead to fatal airway obstruction. 1

Common Infectious/Inflammatory Causes

Viral upper respiratory infection (URI) is the most common cause of nasal congestion at this age, as even minor viral-induced congestion can create near-total obstruction in obligate nasal breathers. 1, 2

Neonatal rhinitis represents generalized nasal airway obstruction commonly seen in this age group. 2

Functional/Reflux-Related Causes

Laryngopharyngeal reflux (LPR) is a frequently overlooked cause that produces nasal congestion through inflammation and narrowing of the posterior choanae. 1

• LPR in infants presents with nasal symptoms, frequent choking, apneic spells, and aspiration of formula leading to secondary chemical/infectious rhinitis. 1
• This can result from prematurity, neuromuscular disease, dysautonomia, velopharyngeal incoordination, or cleft palate. 1
• Diagnosis is usually made with nasopharyngoscopy, though milk scintigraphy or pH probe may be needed. 1

Less Common but Important Considerations

Food allergy (particularly milk/soy) is often suspected by parents but only accounts for 0.3% of rhinitis symptoms in children and adolescents, making it a much less likely cause than commonly believed. 1, 2

Adenoidal hypertrophy, while the most common acquired anatomic cause in infants and children overall, is less likely at 3 weeks of age but should remain on your differential. 1

Rare but Serious Causes

Cerebrospinal fluid (CSF) rhinorrhea should be considered if there is refractory clear rhinorrhea, though this is typically associated with trauma or recent surgery. 1

Primary ciliary dyskinesia can present with recurrent rhinitis and should be considered if congestion persists or recurs frequently. 1

Critical Clinical Pitfall

The narrow margin between therapeutic and toxic doses of medications in infants under 1 year makes pharmacologic treatment extremely dangerous. 1 Topical decongestants should be used with extreme caution below age 1 year due to increased risk for cardiovascular and CNS side effects. 1 OTC cough and cold medications should be avoided in all children below 6 years of age due to documented fatalities (54 deaths with decongestants, 69 with antihistamines in children under 6 years). 1, 3, 4

Diagnostic Approach

• Assess for bilateral vs. unilateral obstruction: Unilateral suggests anatomic abnormality like choanal atresia. 1
• Evaluate feeding and breathing: Difficulty with both suggests significant obstruction requiring urgent evaluation. 2
• Look for associated symptoms: Choking, apneic spells, or aspiration suggest LPR. 1
• Consider timing: Present since birth suggests congenital cause; recent onset suggests infectious or reflux etiology. 2