Most Appropriate Next Investigation for Recurrent Cough Following URTI
For a child with recurrent cough following an upper respiratory tract infection, obtain a chest radiograph and, if age-appropriate (typically >6 years), perform spirometry with pre- and post-bronchodilator testing. 1, 2
Algorithmic Approach to Investigation
Step 1: Determine Cough Duration and Characteristics
- If cough duration <4 weeks: This represents acute/post-viral cough; imaging is usually not appropriate for well-appearing children who don't require hospitalization 1
- If cough duration ≥4 weeks: This is chronic cough requiring systematic investigation with chest radiograph and spirometry 1, 2
- Assess if cough is wet/productive or dry: Wet cough suggests protracted bacterial bronchitis or underlying structural disease, while dry cough may indicate asthma or post-viral inflammation 1
Step 2: Initial Investigations (For Chronic Cough ≥4 Weeks)
Chest Radiograph (CXR)
- Recommended for all children with chronic cough to identify anatomical abnormalities, foreign bodies, or underlying pulmonary disease 1, 2
- Can detect complications like pneumonia, bronchiectasis, or congenital malformations that predispose to recurrent infections 1
- However, note that a completely normal CXR has limited ability to exclude active inflammatory or infectious lung disease (NPV 65-87%) 3
Spirometry (Pre- and Post-β2 Agonist)
- Recommended when age-appropriate (reliably performed in children >6 years, sometimes >3 years with trained personnel) 1, 2
- Abnormal spirometry with bronchodilator reversibility provides objective evidence consistent with asthma 1
- Normal spirometry does not rule out asthma, as it has poor negative predictive value 1
Step 3: Additional Testing Based on Clinical Suspicion
Pertussis Testing
- Indicated when clinically suspected: paroxysmal cough with post-tussive vomiting, inspiratory "whoop", or known contact 1, 2, 4
- The history of recurrent episodes suggests this should be considered 5
Step 4: Evaluate for Specific "Cough Pointers"
Look for red flags that indicate need for more extensive investigation 1, 2:
- Coughing with feeding (aspiration risk)
- Digital clubbing (bronchiectasis, interstitial lung disease)
- Chest deformity
- Growth failure
- Abnormal CXR or spirometry findings
Management Based on Investigation Results
If Wet/Productive Cough Without Specific Pointers
- First-line treatment: 2 weeks of antibiotics targeting common respiratory bacteria (Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis) 1, 2, 4
- If cough persists after 2 weeks: Additional 2-week course of antibiotics 1, 2, 4
- If cough persists after 4 weeks total: Consider flexible bronchoscopy with quantitative cultures and/or chest CT 1, 4
If Dry Cough With Features of Asthma
- Consider trial of asthma therapy if reversible airway obstruction demonstrated 1
- Reassess in 2-4 weeks; discontinue inhaled corticosteroids if no other asthma features present 1
Critical Pitfalls to Avoid
Do not routinely perform additional tests (skin prick testing, Mantoux, bronchoscopy, chest CT) unless individualized based on clinical findings and specific cough pointers 1
Do not use inhaled corticosteroids empirically for post-URTI cough in previously healthy children without evidence of asthma, as they are ineffective for persistent post-viral cough 6, 7
Do not dismiss recurrent wet cough as "just a cold"—persistent wet cough for >4 weeks requires active management to prevent progression to bronchiectasis 4
Assess environmental factors, particularly tobacco smoke exposure, which can exacerbate cough symptoms 2, 4
When to Escalate Investigation
Proceed to advanced imaging (CT chest with IV contrast or CTA) if 1:
- Recurrent localized infections suggesting anatomical abnormality
- Suspected congenital malformations (pulmonary sequestration, vascular ring)
- Abnormal initial chest radiograph
- Failure to respond to appropriate antibiotic therapy after 4 weeks