peritoneal point on ultrasound suggests intraperitoneal free air

Point-of-care ultrasonography can detect many causes of acute hemodynamic instability by revealing sources of sepsis (eg, hydroureter, biliary obstruction, lung consolidation) or other bases for shock (eg, tamponade, hemorrhage, severe cardiac dysfunction, tension pneumothorax). Although CT scanning is often more sensitive and specific, point-of-care ultrasonography can be obtained more readily and without leaving the ICU.

In this case, ultrasonography appears to show a fluid-filled viscus, free peritoneal fluid, then a reverberation artifact typical of intraperitoneal free air. This transition to reverberation artifact is similar to the “lung point” seen with pneumothorax and is termed a “peritoneal point” (or “abdominal point”). Of the choices offered, only a perforated hollow viscus accounts for these findings.

Gas within a hollow viscus can also produce reverberation artifact, but not the sudden transition shown in this case. In addition, a typical finding of free intraperitoneal air is increased echogenicity of the peritoneal line seen well in this case; this is not seen with gas within the bowel or stomach.

When the patient is repositioned, a peritoneal point shifts as expected, giving additional confirmation of the nature of the finding. Pericardial effusion can typically be detected by using an abdominal (subcostal) window, but the curvilinear structure seen in this case is not the heart, and pericardial effusion does not cause reverberation artifact.123

Footnotes

  1. SEEK Questionnaires ↩

  2. Blaivas M, Kirkpatrick AW, Rodriguez-Galvez M, Ball CG. Sonographic depiction of intraperitoneal free air. J Trauma. 2009;67(3):675. PubMed ↩

  3. Hanbidge AE, Lynch D, Wilson SR. US of the peritoneum. Radiographics. 2003;23(3):663-684. PubMed ↩