Point-of-Care Ultrasound Techniques for the Small Animal Practitioner. Группа авторов
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“hourglass like,” is found between loops of small intestine.
Source: Reproduced with permission of Dr Gregory Lisciandro, Hill Country Veterinary Specialists and FASTVet.com, Spicewood, TX.
Figure 6.33. False positives at the HRU (SRU) view. In (A) and (C) are the abdominal radiograph and the HRU (SRU) view of a patient in which necrotic masses can have intracavitary necrosis with triangulations of fluid mimicking free fluid. Increasing your depth and sliding and sweeping your probe to add more interrogation (or adding a radiograph especially if the AFAST was performed first) is important. If the radiograph was the initial imaging test, AFAST helps differentiate free fluid from a mass or to determine that both are present. By assigning an AFS and performing abdominocentesis, fluid analysis, and cytology, decision making is expedited in most cases. (B) and (D) show an example of pyometra and how the compartmentalization of the uterus may appear like free fluid. The addition of an abdominal radiograph is complementary for best interpreting the AFAST study.
Source: Reproduced with permission of Dr Gregory Lisciandro, Hill Country Veterinary Specialists and FASTVet.com, Spicewood, TX.
The HR5th bonus view's target organs are the liver and right kidney (or left kidney and head of the spleen).
The probe should be directed craniodorsal for the HR5th bonus view, and analogously for the SR5th bonus view.
The author likes to find the liver and then fan through it, sliding caudally because in dogs the right kidney is cupped by the liver in its renal fossa. Thus, if you run out of liver, then you need to restart cranially within the liver again.Figure 6.34. HR5th view on a dog. In (A) two different approaches are shown imaging the HR5th bonus view in which the right kidney and liver are in fact interrogated. In (A) the lateral recumbent method uses the same landmarks as the SR view where the costal arch meets the hypaxial muscles, but the probe is often directed much more cranially because the right kidney in the dog lies further cranially than its left counterpart (in contrast to cats not so much further cranially). The author prefers performing the HR5th bonus view (or SR5th bonus view in left lateral recumbency) with the patient standing after the four views of AFAST, TFAST and Vet BLUE have been completed leaving the HR5th (SR5th) bonus view as the final acoustic window. The same landmarks used in lateral are used in standing. The author avoids imaging between ribs if possible but either approach is acceptable (sonographer preference). In (B) and (C) are unlabeled and labeled CT images to better illustrate the anatomy. In (D) and (E) are typical negative studies of the HR5th bonus view unlabeled and labeled. Use the diaphragm as a landmark to find and follow the liver, which will lead you to the right kidney in dogs. LIV, liver; RK, right kidney.Source: Reproduced with permission of Dr Gregory Lisciandro, Hill Country Veterinary Specialists and FASTVet.com, Spicewood, TX.
The diaphragm is a good landmark and helps locate the liver since the liver abuts the diaphragm.
The liver and right kidney are then fanned through, searching for free fluid and screening for soft tissue lesions.
Typical HR5th Bonus View Positives
Free fluid located around the right kidney and between the right kidney and the liver displacing the right kidney from its renal fossa in dogs. The SR5th bonus view is performed just like the SR view.
False Positives
The caudal vena cava and other vasculature, aorta and portal vein, run through this region and can be confounders for free fluid (see Chapter 26). Color flow Doppler and holding the probe stationary in B‐mode and watching for pulsation are other options to differentiate free fluid from venous or arterial blood flow. These vessels are generally not problematic at the SR and SR5th bonus views.
False Negatives
Similar to the other AFAST views of missing small volumes, thus always performing at least one more AFAST is recommended as standard of care even in “stable” patients.
Pearl: The HR5th (and SR5th) bonus views are not part of the AFS.
Pearl: Consider the 5th bonus view as exactly that, a “bonus,” not mandated but considered as an add‐on skill once image acquisition is perfected at the first four AFAST views.
AFAST‐Focused Spleen
The AFAST‐focused spleen should be performed after every AFAST if the spleen is imaged at the HRU (SRU) view (Figure 6.35). The author has routinely adopted this practice since the recognition of medically treated anaphylaxis‐induced hemoabdomen in dogs (Lisciandro 2016a,b; Caldwell et al. 2018; Hnatusko et al. 2019; Birkbeck et al. 2019). The approach is that a positive AFAST‐focused spleen for a mass is likely highly specific (the mass is real). In contrast, a negative AFAST‐focused spleen doesn't rule a mass out (dependent on the operator). The AFAST‐focused spleen is a screening test. For more detail, see Chapter 9.
The spleen is identified by the finding of a hyperechoic capsule and the blood supply splitting the capsule.
The slide and fan technique is repeated through successive sections while overlapping between sections. A more detailed evaluation may be found in Chapter 9.
Scan cranially and then caudally to each end of the spleen. The author performs this twice and makes sure that the spleen was maximally imaged at the SR view.
A mass that deforms the capsule of the spleen is always considered a serious finding.
Recording AFAST Findings on Goal‐directed Templates
Recording your findings is imperative for a successful ultrasound program. See Chapter 7 and the Appendices.
Pearls and Pitfalls, The Final Say
AFAST is a standardized ultrasound examination with exact clarity of its five acoustic windows and how each is performed. AFAST has been shown to be superior to radiography for not only the detection of free intraabdominal fluid but also the volume through its AFAST‐applied fluid scoring system (Lisciandro et al. 2009, 2015, 2019). Moreover, the AFAST DH view is an important source of patient information for free fluid, volume status, pericardial and pleural effusion and lung conditions. Chapter 7 covers clinical integration of AFAST‐acquired information.
AFAST has exact clarity to its five acoustic windows.
AFAST and its acoustic windows are exactly the same no matter the patient positioning.
Each view has target organs that are imaged while looking for free fluid (intraabdominal, retroperitoneal, pleural, pericardial) and lung conditions.
AFAST should be part of any POCUS abdominal examination to make sure that effusions or other obvious target organ pathology are not missed.
Serial AFAST and an assigned abdominal fluid score should be repeated, called the serial exam, four hours after the initial AFAST in all stable patients