Sonographic diagnosis of intraperitoneal free air.

Detection of intraperitoneal free air is important for the diagnosing of life-threatening conditions in patients with acute abdominal pain. Point-of-care ultrasound is an extension of the clinical examination in patients presenting with acute abdomen. Failure of sonographers to detect intraperitoneal free air was clinically considered as a limitation of abdominal ultrasound. It is now increasingly appreciated that ultrasound may detect intraperitoneal free air. Emergency physicians should be familiar with the sonographic features of intraperitoneal free air which may be essential to recognize bowel perforation. Herein we review the literature on the sonographic findings of intraperitoneal free air and the technical manoeuvres that can improve clinicians' detection of intraperitoneal free air using point-of-care ultrasound.