The FAST exam consists of views of the right upper quadrant (RUQ), left upper quadrant (LUQ), pelvis, and pericardium, but the LUQ view is often the most challenging to obtain and deserves some special attention.
The liver provides an excellent window to view surrounding structures in the RUQ, but the LUQ relies on the smaller, less helpful spleen. Anatomically, the spleen is typically more posterior and cephalad than the liver, making visualization difficult at times. Multiple potential spaces in the LUQ, however, are critical to evaluating for free fluid. The spleen is intraperitoneal, creating potential spaces above (between the diaphragm and spleen) and below (between the spleen and left kidney). The area around the inferior pole of the kidney, which extends toward the left paracolic gutter, is an important potential space as well.
I typically begin my evaluation of the LUQ in a coronal orientation with the probe indicator toward the patient's head. The kidney appears largest in this view, making it easier to find. Conventional wisdom states that the transducer should be placed on the posterior midaxillary line, between the sixth and ninth rib interspace. (Image 1.) A good rule is “knuckles to the bed,” meaning if you are standing on the patient's right and reaching over him, your knuckles will almost be resting on the bed.
A good LUQ view demonstrates not just the spleen and kidney (Image 2) but also the diaphragm and lower chest. To accomplish this, it may be necessary to evaluate the area in parts, first the spleen and kidney and then moving the transducer superiorly to the diaphragm. Slightly rotating the transducer so that it lies on more of an oblique plane allows the examiner to avoid rib shadowing. Asking a cooperative patient to breathe in deeply and hold it for as long as possible can also be a big help. This expands the thorax and causes the spleen and kidney to become more caudal; be prepared to bring your transducer more inferior to follow your view.
Once a good view has been obtained, the LUQ is relatively straightforward to evaluate. One potential pitfall is the fundus of the stomach, which can resemble free fluid when fluid-filled. The stomach can be distinguished by several factors. Typically, it will appear rounded and contained, while free fluid is irregular and not contained. The stomach may also demonstrate particulate floating within it.
Dr. Buttsis the director of the division of emergency ultrasound and a clinical assistant professor of emergency medicine at Louisiana State University at New Orleans. Follow her on Twitter @EMNSpeedofSound, and read her past columns athttp://bit.ly/EMN-SpeedofSound.
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