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Slice‐thickness artifact is somewhat like the side‐lobe artifact. In the gallbladder and urinary bladder in particular, this artifact mimics sludge or sediment. It occurs when part of the beam's thickness lies just outside a fluid‐filled structure. These artifacts typically appear within the lumen of these structures and are somewhat hyperechoic (bright) and curved. They can be differentiated from real sediment by several methods or clues. First, gravity‐dependent sediments have a flat surface whereas the artifact will be rounded. Second, by changing the position of the patient, the relative position of true sediment will change as gravity pulls it to the new lower point. Third, the sonographer can use the ultrasound probe to ballot the bladder and stir the sediment up a bit; the artifact will not yield a “snow globe” effect (sediment will) (Penninck 2002) (see Figure 3.7).