are found at three of the four views which calculates as an AFS of 1.5, a “small‐volume bleeder/effusion.” In (C) there are larger pockets of free fluid (1 + 1 + 1) at the same three AFAST views as in (A) and the AFS calculates as 3, a “large‐volume bleeder/effusion.” In (D) there are small triangulations at the DH and SR views and a larger pocket at the HRU view with a calculated AFS of 2 (½ + ½ + 1), a “small‐volume bleeder/effusion.” The same concept is applied to dogs.
Source: Reproduced with permission of Dr Gregory Lisciandro, Hill Country Veterinary Specialists and FASTVet.com, Spicewood, TX. Illustration by Hannah M. Cole, Adkins, TX.
Pearl: Cats with automobile‐induced traumatic hemoabdomen are often nonsurvivors before making it to veterinarians because they cannot compensate as dogs do and because of their smaller size, making injury more severe and lacking a splenic blood reservior. Free fluid on AFAST in surviving cats (>12–24 hours) is more likely to be urine than blood.
Importance of Recording Locations of Where Patients are Positive
It is imperative to not only record the AFS but also locations of where the patient is positive and negative. This is important because the locations of AFAST‐positive views in lower‐scoring “small‐volume bleeders” may be helpful for the localization of the bleeder (Table 7.4). For example, consider a hit‐by‐car dog or cat with an AFS of 1 at the AFAST DH view that continues to bleed with an increase in AFS to 3 or 4 and that despite blood transfusions becomes a surgical case. Logic would dictate that the source of intraabdominal bleeding is likely associated with the liver and its vasculature. This information would potentially better prepare the surgeon for the anticipated type of injury, such as liver laceration, hepatic venous or vena caval injury, and for the needed procedure(s) as well as relevant resources. On the other hand, in the same trauma scenario the AFS 1 is positive at an AFAST view further caudally, such as the CC or HR umbilical view, and now logic would dictate that the source of bleeding would be more likely intestinal tract or spleen. Thus, the definitive procedure would likely be less technically challenging than a liver laceration or vascular hepatic injury.
Table 7.4. Possible sources of abdominal bleeding on AFAST views.
Source: Reproduced with permission of Dr Gregory Lisciandro, Hill Country Veterinary Specialists and FASTVet.com, Spicewood, TX.
| View | Possible source |
|---|---|
| DH | LiverVascularCaudal vena cavaHepatic vesselsPortal vessels |
| SR, HR, SR5th, HR5th | Spleen (SR, SR5th)Liver (HR, HR5th)AdrenalOvaryVascularCaudal vena cavaAortaRenal vesselsVertebrae |
| CC | Small intestineLarge intestineReproductive tractUterusProstateVascularCaudal vena cavaAorta |
| HRU, SRU | LiverSpleenUterusGastrointestinal tract |
In nontrauma, another example would be a postovariohysterectomy bleeding case with an AFS of 1 that is positive at the SR view. Let's say that over time, the patient progresses to an AFS of 3 or 4 that requires surgical exploratory. Logic would dictate the source of bleeding is most likely in the vicinity of the SR view and the left ovarian pedicle would be suspect. This information would again help direct the surgeon to that region as initially AFAST positive for the source of bleeding. In fact, for bleeding postoperative ovariohysterectomy surgeries, the AFAST acoustic windows are in regions of the left ovarian pedicle (SR view), the right ovarian pedicle (HR5th bonus view), and the uterine stump (CC view), which is important to consider in “small‐volume bleeders” that progress to “large‐volume bleeders” requiring surgical intervention. The upshot is that the sonographer should record both the AFS and specifically what AFAST views are positive and negative to maximize patient information as dictated in AFAST goal‐directed templates (see last section of this chapter).
Pearl: Use the AFAST and AFS system as a postinterventional exit exam evaluation, e.g., postoperative and postpercutaneous ultrasound‐guided procedures, before patients are sent home to ensure no occult bleeding is occurring. The use of this strategy is more sensitive than a physical exam, vital signs, and packed cell volume and total solids.
Most Common AFAST‐Positive Sites in Low‐Scoring AFS 1 and 2 Patients
In trauma, the most commonly reported positive sites are the nongravity‐dependent DH and CC views, which is against logic, which would dictate that the most gravity‐dependent HRU view would be more likely to be positive (SRU view in left lateral recumbency) (Lisciandro et al. 2009, 2019; Romero et al. 2015). In nontrauma, the most gravity‐dependent and least gravity‐dependent views were most commonly positive and surprisingly in equal distribution (McMurray et al. 2016), also defying logic. Lastly, in clinically normal puppies and kittens, the DH and CC views were most commonly positive (Lisciandro et al. 2015, 2019; Romero et al. 2015). The upshot is that sonographers should be aware of the pitfalls and artifacts for all AFAST views in order to maximize identifying free fluid over confounders since there is variation in the most commonly detected positive AFAST views between patient subsets and ages. These pitfalls and artifacts are well detailed in Chapter 6.
AFAST Limitations for Intrapelvic Bleeding
People with femoral and pelvic fractures can lose 50–75% of their blood volume at the fracture site, respectively (Coccolini et al. 2017). In dogs and cats, this is uncommon but does occur and should be considered in anemic cases in which the source of the large volume of blood loss is inapparent (Lisciandro 2012). Importantly, FAST has been shown to perform poorly for detecting intrapelvic bleeding and the AFAST sonographer should consider this limitation. Through an understanding of ultrasound and imaging of soft and hard musculoskeletal tissues, however, it seems possible that large blood clots and hemorrhage could potentially be detected at fracture sites through the combined use of B‐mode and color flow Doppler (see Chapters 34 and 35).
Use of the AFAST AFS System as an Exit Exam Postintervention
Physical examination, laboratory testing, and radiography are insensitive and unreliable tests for the presence of free fluid in small animals (Rozycki 1998; Rozycki et al. 1998, 2001; Boysen et al. 2004; Lisciandro et al. 2009; Lisciandro 2012; Boysen and Lisciandro 2013; McMurray 2016), and there is no reason to think that this would be different for postinterventional cases. After any invasive procedure that places your patient at risk for bleeding, the AFAST and its applied fluid scoring system should be used as standard of care. By having an AFAST and AFS documented pre‐ and postinterventionally (or, even better, the Global FAST approach – see Chapters 36 and 37), during follow‐up examinations the continued use of AFAST and AFS (Global FAST) may help to detect complications earlier in their course.
The value of the FAST approach for postinterventional monitoring has clearly been shown in people (Rozycki 1998; Rozycki et al. 1998, 2001). Initial and serial AFAST with an AFS will help survey for ongoing bleeders. In addition, the technique aids in the detection of “large‐volume
