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False positives are generally not a problem at the CC view when directing the probe into the “CC pouch,” the most gravity‐dependent region between the urinary bladder and the body wall in the far‐field. The great vessels are in the opposite direction, located sublumbar, which is not an imaging plane for the CC view.

If you fan dorsally into the sublumbar area, generally unnecessary during AFAST, the great vessels, female reproductive tract, and lymph nodes may become confounders because they are generally anechoic fluid‐filled structures or hypoechoic structures, respectively.

Figure 6.24. Examples of typical negative studies at the CC view. In all these images, note how readily recognizable is the filled urinary bladder as a landmark along with the body wall in the far‐field within the “CC pouch.” The “CC pouch” is very sensitive for detecting small‐volume effusions as noted in (C) and (F) and the small anechoic triangulation circled, which in fact may be considered a normal finding in juvenile puppies and kittens with abdominal fluid scores of no more than 1. In fact, adult dogs and cats may also have a small amount of free fluid (<3 mm) at the CC view as the only positive AFAST view. The only other typical abdominal structures in these images are small intestine. Because of its facial planes and acoustic enhancement through the fluid‐filled urinary bladder, the body wall is typically a hyperechoic (bright white) line. Images (A), (B), (D) and (E) are negative CC studies. Note the consistency in the images with their proportionality and location of the relevant CC view structures of the urinary bladder, “CC pouch”, and body wall.

Source: Reproduced with permission of Dr Gregory Lisciandro, Hill Country Veterinary Specialists and FASTVet.com, Spicewood, TX.

Figure 6.25. Examples of typical positive studies at the CC view. In (A), (C) and (E), CC view positives are shown with a urine‐filled urinary bladder in contrast to images in (B), (D) and (F) in which the urinary bladder is not readily apparent as in (B) or absent in (D) and (F). The urinary bladder is likely not ruptured, as most of these patients are nontrauma cases, and the probe could be slid caudally and/or directed toward the pubis to locate a small urinary bladder. In the absence of a urinary bladder, the serial AFAST examination post resuscitation is invaluable to determine the presence of the urinary bladder and urine production. Note the consistency in the images with their proportionality and location of the relevant CC view structures of the urinary bladder, “CC pouch”, and body wall.

Source: Reproduced with permission of Dr Gregory Lisciandro, Hill Country Veterinary Specialists and FASTVet.com, Spicewood, TX.

Figure 6.26. Relevant artifacts at the CC view. (A) A mirror image artifact is present beyond the body wall and marked with an asterisk (*). Placing the focus cursor in the center of the image and changing the angle of insonation can help eliminate mirror image. Acoustic enhancement artifact, the hyperechoic body wall, is also present through the fluid‐filled urinary bladder and its cranial and caudal borders marked (V). In (B) the acoustic enhancement artifact is again marked (V). The arrows outline the borders of a slice‐thickness artifact that mimics sediment. Turning down the gain will reduce the artifact whereas sediment will persist. Color flow Doppler will also demonstrate there is no flow through the artifact. In (C) is another example of acoustic enhancement artifact with marked borders (V). In (D) probe pressure deforms the shape of the urinary bladder, making it “dumbbell” or “figure 8” shaped, and is often uncomfortable for your patient. When measuring the urinary bladder for volume estimation, probe pressure will contribute to error.

Source: Reproduced with permission of Dr Gregory Lisciandro, Hill Country Veterinary Specialists and FASTVet.com, Spicewood, TX.

Pearl: Direct the probe into the “CC pouch” as a general rule of thumb to avoid confounders.

Pearl: Note that in puppies and kittens <6 months of age (and even up to 9 months), many have small volumes (<3 mm maximum dimension) of anechoic free fluid (ascites) that is considered normal (Lisciandro et al. 2015, 2019; Stander et al. 2010), having AFS of 1 and 2. These juveniles are most commonly positive at the CC, SRU and DH views (Lisciandro et al. 2015, 2019; Romero et al. 2015).