This diagnostic accuracy study aims to evaluate the performance of bedside ultrasound compared to x-ray in detecting the correct position of feeding tubes among critically ill adult patients. The main questions it aims to answer are: • diagnostic accuracy of bedside ultrasound • feasibility of its wide adoption among practitioners with minimal training in busy intensive care units.

This multicenter diagnostic accuracy study consists of a non-consecutive convenience sample of adult patients admitted to the intensive care unit starting from March 2023 who require a feeding tube as defined by the medical attending team.

Right after feeding tube placement following the institutional standard operating procedure, attending physicians perform bedside ultrasound assessment to verify the correct position of the tube. They report whether or not visualizing the feeding tube in four steps: 1) in the esophagus from either the right or left side of the patient's neck; 2) in the transverse view of the patient's epigastrium; 3) in the longitudinal view of the patient's epigastrium and 4) during the injection of 20 mL of air into the tube to detect the 'fogging sign.' Finally, the abdominal radiograph (gold standard) confirms the gastric or duodenal placement of the feeding tube.

Inclusion Criteria:

• Age greater than or equal to 18 years old;
• Need for a tube feeding for receiving diet and/or medication, as indicated by the medical team;
• Blind insertion of a tube feeding in the intensive care unit, following the standard operating procedure;
• Presence of a trained physician for ultrasound scanning of the tube feeding immediately after installation.

Exclusion Criteria:

• Major abdominal postoperative wounds, peritoneostomy, or any other conditions that preclude ultrasound abdominal examination;
• Exclusive presence of a gastric decompression probe, which does not require radiographic confirmation;
• Tube feeding introduced under digestive endoscopy guidance;
• Gestation;
• Abdominal radiography confirming the tube position obtained before the ultrasound assessment.

Adult critically ill patients admitted in the intensive care unit undergoing a tube feeding placement as defined by the attending medical team and in accordance with the institutional standard operating procedure.