One common source of confusion or false positives in the FAST exam is the assessment of the left upper quadrant. We’ve already covered some tips on improving your view of the spleen. This post will illustrate how the stomach can mimic free fluid to the unprepared.

The first image shows a perisplenic (left upper quadrant) view on ultrasound. Note the spleen (S), kidney (K), and diaphragm (D).

As the operator fans anterior and posterior to assess for fluid, anechoic fluid with some dirty shadows and slightly irregular margins is seen (bounded by arrows). This structure is often visualized anterior and medial to the spleen, and represents fluid within the stomach.

The video better illustrates fanning through a sagittal plane and encountering this common artifact.

Scan through the area carefully to ensure this fluid is all accounted for within the confines of the stomach, and does not layer out around the kidney, spleen, or highlight bowel loops at its margins.