The inclusions have been suspended from 03/18/2020 during the confinement period.

In the meantime, a publication has appeared showing that the chest ultrasound has entered the common practice in the management of bronchiolitis.

The diagnosis of bronchiolitis, the most frequent lung infectious disease in infancy, is based on clinical examination. Chest X-ray is proposed when a lung parenchymal condensation is suspected. Chest ultrasound is supposed to be a useful tool in the diagnosis of these complication but is poorly evaluated. We aim to compare chest X-ray and chest ultrasound for the diagnosis of parenchymal condensation in infant with bronchiolitis.

900 to 1000 children are admitted each year for bronchiolitis in the pediatric emergency department of the Toulouse Children Hospital. The diagnosis is based on clinical examination, but in some cases furthers examinations such as chest X-ray are necessary in order to look for a parenchymal condensation. Even if French recommendations do not place chest ultrasound in the care pathway to date, many recent studies show the usefulness, rapidity and reliability of ultrasound in parenchymal abnormalities. But regarding the bronchiolitis, few studies are available and including limited numbers of patients. In addition, the reduction of irradiation is a main goal, especially in children.

We propose to performed a chest ultrasound in infants (<24 months) admitted for bronchiolitis with an available chest X-ray, in order to compare the performance of both examinations (X-ray and ultrasound) for the diagnosis of parenchymal condensation. Besides, to correlate initial chest ultrasound results and clinical evolution, parents will be contacted by phone 1 month after inclusion.

Primary outcome: The primary outcome is the sensitivity and specificity values of chest ultrasound for the diagnosis of parenchymal condensations diagnosed by chest X-ray. Positive and negative predictive values will also be estimated. This outcome is evaluated at the first visit (T0).

Secondary outcomes:

• To describe chest X-ray and ultrasound abnormalities in bronchiolitis.
• To evaluate the performance of chest ultrasound to distinguish retractile and non-retractile opacities complicating bronchiolitis.
• To study the correlation between clinical evolution at 1-month (malaise, place and duration of hospitalization, re-hospitalization, oxygen therapy, antibiotic therapy) and chest ultrasound results.

Follow-up parameters are recorded during a telephone call 1 month after inclusion.

Study design : It is a longitudinal, monocentric and prospective study with the aim to evaluate a diagnostic examination.

Inclusion Criteria:

• Two years old patient at emergency Hospital (CHU-Toulouse) for bronchiolitis and performing of thoracic radiology
• Informed consent formed to sign by family before the exam and the evidence of social security regime affiliation.

Exclusion Criteria:

• Patient with cardiopulmonary disease or underlying immunosuppression