Objective. Sonography is a reliable imaging tool, complementary to plain radiography in certain pediatric chest disorders. It can assist in localizing and characterizing mediastinal, pleural, and pulmonary opacities. We have found that sonography is also valuable in elucidating postoperative chest radiography. In this series, our objective was to assess the value of sonography for understanding the radiologic changes in the child after esophagectomy and to highlight its ability to show the intrathoracic stomach. Methods. Sonography was performed with a 5- to 12-MHz linear array transducer via anterior, lateral, and posterior intercostal approaches of the abnormal hemithorax in supine, prone, and, when necessary, upright positions. Results. The distended fluid- or food-filled stomach was identified on sonography as the source of the undefined thoracic opacity on plain radiography in 2 patients. Conclusions. The postoperative pediatric chest radiograph is often difficult to understand. Sonography can differentiate between lung consolidation or pleural fluid and a food- or fluid-filled stomach. Simple maneuvers such as postural changes can confirm in the diagnosis.