Signs and symptoms cannot be used to differentiate etiology of CAP.
Relevant history includes: cough, nasal congestion, shortness of breath, wheezing, abdominal or chest pain, presence and duration of fever, oral intake, urine output, vomiting, and sick contacts.
While no individual examination finding is sensitive or specific for making the diagnosis,¹ hypoxemia and work of breathing have better correlation with radiographic pneumonia than other findings. Published clinical prediction rules suggest that combinations of findings (age, fever duration, hypoxemia, rales, diminished breath sounds) may be more useful than individual findings, but these rules require validation.^2,3
Wheezing is negatively associated with radiographic pneumonia.⁴

For children with mild CAP (i.e., no substantial respiratory distress or hypoxemia) or where the history and physical are more suggestive of bronchiolitis (i.e., children <2 years old with symptoms of an upper respiratory infection and diffuse coarse breath sounds or wheezing), imaging is not indicated as it does not change outcomes and leads to antimicrobial overuse. Refer to TREKK Recommendations on Bronchiolitis.
Chest radiography (CXR) should be obtained if:
- the diagnosis of CAP is uncertain,
- there is concern for complicated pneumonia,
- and/or the patient requires hospitalization.
In outpatients, it is reasonable to treat empirically without CXR when clinical suspicion is high.
Intra- and inter-rater reliability for the identification of streaky or interstitial infiltrates on CXR is limited, though reliability is better for lobar consolidations.
Children with no infiltrate on CXR are extremely unlikely to have CAP. The presence of an infiltrate on CXR does not necessarily mean that the child has bacterial disease.⁵
Chest ultrasound may serve a role in diagnosing CAP and may be a suitable replacement for CXR in the presence of a trained provider.⁶ Ultrasound can identify and characterize parapneumonic effusions and empyemas.

Laboratory testing (e.g., complete blood count, C-reactive protein, or procalcitonin) is not helpful in the diagnosis of CAP but may be helpful in cases where CXRs are indeterminate or to assist with prognostication, particularly for hospitalized patients.
Blood cultures are not advised for patients with CAP unless they are ill-appearing or require hospitalization with moderate to severe disease, due to the low yield of pathogenic bacteria and risk of contaminated culture in most children with CAP.⁷