(cm) (Figure 7.15).
Calculate urinary bladder volume using length × height × width (cm) × 0.625 = estimation of urinary bladder volume (mL) (see Figure 7.15).
Urine output is estimated using change in urinary bladder volume/time.
AFAST and Its Target Organ Approach
AFAST was never meant to be a “flash exam” of the abdomen. The “flash” mentality is a quick ultrasound sweep answering a single binary question of whether fluid is present or absent, a positive or negative test. It is often used as a desultory sweep for a midabdominal mass, but without standardization of views and knowledge of anatomy at specific acoustic windows as in AFAST. Without direction, it becomes easy for the sonographer to get lost. Easily detected soft tissue conditions are often missed by abdominal radiography (Table 7.9) and the reader is referred to Chapters 8–12. The objective is through repetition and standardization to be able to tell normal from abnormal (differentiate expected from unexpected) and capture conditions that would otherwise be missed without any imaging or with radiography. As you read through Table 7.9, think about the conditions listed and how often they are missed on plain radiography. Interestingly, incidental findings during FAST exams have been reported in people (Sgourakis et al. 2012).
Figure 7.15. Measurements at the AFAST CC view for estimating urinary bladder volume. In (A) the best largest oval in the longitudinal plane is used for length (L, cm) and height (H, cm) measured as 5.01 cm and 3.22 cm, respectively. In (B) the best largest oval in the transverse plane is used for width (W, cm) measured as 4.49 cm. With these measurements the equation would be 5.01 × 3.22 × 4.49 cm × 0.625 = 45.3 mL. The volume can be compared to that aspirated when patients are catheterized immediately thereafter to gain confidence in its use (Lisciandro and Fosgate 2017).
Source: Reproduced with permission of Dr Gregory Lisciandro, Hill Country Veterinary Specialists and FASTVet.com, Spicewood, TX.
Table 7.9. AFAST and its target organ approach as a soft tissue screening test.
Source: Reproduced with permission of Dr Gregory Lisciandro, Hill Country Veterinary Specialists and FASTVet.com, Spicewood, TX.
| View | Target organ | Findings |
|---|---|---|
| DH | Gallbladder | SludgeMucoceleCalculiMasses |
| Liver | MassesObvious mottled echogenicity | |
| Caudal vena cava | Caudal caval size abnormalitiesCaval syndromeHepatic venous congestion | |
| Lung | Alveolar‐interstitial edema (B‐lines)ConsolidationMasses | |
| Heart | Pericardial effusionLeft atrial enlargement | |
| Thorax | Pleural effusionMasses | |
| SR, HR, SR5th, HR5th | KidneyLiver | PyelectasiaHydronephrosisCortical cyst(s)Perinephric cyst(s)Polycystic diseaseMassesSee DH view |
| CC | Urinary bladder | SedimentCalculiBladder wall irregularitiesMasses |
| HRU, SRU | Spleen | MassesObvious mottled echogenicityMidabdominal masses |
See respective POCUS abdomen‐related chapters for examples.
Recording AFAST Findings on Goal‐directed Templates
The use of standardized templates is imperative not only for communication of AFAST findings between veterinarians but also for the attending clinician evaluating serial findings (Figure 7.16). Goal‐directed templates also clearly define objectives, which is especially important in teaching hospitals and referral hospitals with multiple disciplines of practice including emergency and critical care, cardiology, and radiology. Being goal driven, these standardized templates also accelerate the learning curve and discipline the sonographer by making them look at certain aspects of the target organs (into the thorax for pleural and pericardial effusion [DH view]; looking at the hepatic veins for venous congestion [DH view]). The “Comments” allows for any findings outside the goal‐driven standard format to be listed, for example suspect a urinary bladder stone or mass, suspect a splenic mass, etc. Finally, the AFAST protocol and its strengths and weaknesses may be evaluated and improved upon with recorded data. Suggested templates for medical records are shown in Chapter 45 and Appendix I.
Pearls and Pitfalls, The Final Say
AFAST is superior in detecting hemorrhage to laboratory values (packed cell volume, lactate), physical examination findings, and radiography (Lisciandro et al. 2009; Rozycki 1998; Rozycki et al. 1998, 2001; McMurray et al. 2016). AFAST is an advantageous ultrasonographic format for nonradiologist veterinarians to use for the timely detection of free fluid representing bleeding or forms of peritonitis since ultrasound is superior in sensitivity to physical examination and abdominal radiography.
Should be a routine add‐on for all POCUS abdominal exams (Global FAST is an even better approach).
Should be standard of care for all bluntly traumatized small animals, as it is in people.
Should be used in penetrating trauma cases with the understanding that AFAST is generally thought to be very specific for detecting intraabdominal injury (by finding free fluid), but lacks high sensitivity.
Serial exams should always be performed in bluntly traumatized animals, after rehydration and resuscitation in trauma and nontrauma including suspect peritonitis cases.
The use of the AFAST‐applied abdominal fluid scoring system may be effective in bleeding traumatized and nontraumatized dogs to predict degree of anticipated anemia and may be used also for peritonitis or other effusive conditions as a monitoring tool by scoring (AFS 0–4).
The diagnosis of anaphylaxis in dogs may be supported with the finding
