Detection of intraperitoneal free gas by ultrasound

Introduction: Patients with acute abdominal pain may have unsuspected pneumoperitoneum, and be investigated with ultrasound. Although not the primary imaging modality for this condition, ultrasound will usually demonstrate signs of free intraperitoneal or extra-luminal gas. Methods: Sonographic signs of pneumoperitoneum are described, along with the limitations and pitfalls of the technique. The reported accuracy of these signs is described. Conclusion: The different signs that may be seen are described, and it is suggested that all who ultrasound patients for abdominal pain should be aware of these.