The use of the AFAST-applied Abdominal Fluid Scoring System was published by Lisciandro et al. J of Vet Emerg and Crit Care, 2009. In the study, 101 bluntly traumatized dogs were evaluated using AFAST initially and serially 4-hours post-admission with a determined abdominal fluid score based on the number of AFAST positive sites (4 -sites: Diaphragmatico-hepatic [DH], Spleno-renal [SR], Cysto-colic [CC], and Hepato-renal [HR]). Thus, the patient’s abdominal fluid score (AFS), is calculated as follows: AFS 0 (no positive sites), AFS 1 (positive at any single site), AFS 2 (positive at any 2 sites), AFS 3, (positive at any 3 sites), and AFS 4 (the maximum score, positive at all 4 sites).

Small Volume vs Large Volume Bleeder, revised, October 4, 2014

The  results of the study support that the assignment of an AFS to dogs gave more meaning to a positive AFAST exam by semi-quantitating the volume of intra-abdominal blood. Dogs with lower-scoring AFS of 1 or 2 were unlikely to become anemic from their intra-abdominal bleeding (Statistically Significant, P < 0.05). Thus, an AFS 1 or 2 dog (that remains an AFS 1 or 2 on serial AFAST exams) with anemia (PCV <35%) has either pre-existing anemia, is bleeding at another location (externally, fracture site, large space such as pleural or retroperitoneal spaces), or is hemodiluted, or has combinations of any of these factors. In summary, it is not expected for a dog with an AFS 1 or 2 that does NOT increase in score (AFS from a 1 or 2 small volume bleeder to an AFS 3 or 4 large volume bleeder on serial examination) to become anemic solely from their intra-abdominal bleed if they were healthy prior to their injury. This information proves very important when managing hit-by-car dogs.

On the other hand, dogs with AFS of 3 or 4 predictably became anemia (PCV< 35%), and one-quarter became anemic enough (PCV <25%) to be considered blood transfusion candidates (Statistically Significant, P <0.05). Thus, dogs with blunt trauma could be differentiated into 2 groups: lower-scoring AFS 1 and 2 dogs being designated as “small volume bleeders”; and higher-scoring AFS 3 and 4 dogs being designated as “large volume (big) bleeders.” It should also be noted that any dog with a positive AFAST exam should be considered as having a MAJOR intra-abdominal injury until proven otherwise with strict exercise restriction for 2-3 weeks post-injury. The AFS does NOT correlate with the severity of injury.

The application of the AFAST-apllied fluid scoring system is simple and easy to remember; and should be incorporated into AFAST goal-directed templates as well as the specific locations of the positive sites. By recording not only the AFS (0-4) but also the specific positive sites, the location of the source of bleeding in lower-scoring dogs (AFS 1 and 2) that continue to bleed and become higher scoring dogs (AFS 3 and 4), as logic would dictate, would likely have the source(s) of hemorrhage in the vicinity of the initial positive site(s). This information may help more expediently direct the surgeon to the injured area when emergent laparotomy was warranted; and also be helpful in determining the skill set needed by the surgeon (DH positive AFS 1 that progresses to AFS 3 or 4 may have a technically challenging liver or caval or hepatic venous injury vs. a CC positive AFS 1 that processes to an AFS 3 or 4 that has a less challenging splenic or mesenteric injury).

It is important to know that MOST dogs with blunt trauma-induced hemoabdomen can be medically managed without surgery (blood transfusions +/- fresh frozen plasma). So don’t rush a higher-scoring hit-by-car immediately into the operating room, but rather resuscitate with judicious fluid therapy and plan on the need for blood transfusion sometime over the next several hours. Knowing that a dog is a high-scorer on presentation helps direct planning and resources ahead of time!

In contrast to blunt trauma, we will discuss 2 additional subsets of dogs with hemoabdomen.

First, post-interventionally (post-op abdominal surgery or percutaneous procedures), higher-scoring dogs with hemoabdomen without coagulopathy likely need to be explored sooner than later because in time they will become anemic (and once they decompensate from ongoing bleeding now may need transfusions, additional resuscitation, that escalate client cost); and their bleeding is unlikely to stop on its own (without surgical intervention and stopping the source(s) of bleeding). Our philosophy is if a post-interventional case, i.e. post-op spay, is an AFS 3 or 4, you must explore as soon as possible. We also recommend using AFAST and its applied-abdominal fluid scoring system as standard of care in all post-interventional cases to evaluate for bleeding complications since the approach is likely much more sensitive than traditional means of bloodwork, vital signs, physical examination and radiographic findings as documented in human medicine. For example, if a percutaneous ultrasound guided procedure is performed in the morning, an AFAST and AFS should be performed 4-6 hours later to make sure now unrecognized bleeding is taking place before the patient is released as an outpatient.

Regarding non-traumatic hemoabdomen (the bleeding intra-abdominal mass), pre-operatively, likely at triage when using AFAST as a first line screening test, AFS may be used similarly in that lower-scoring non-traumatic hemoabdomen dogs should not be anemic on presentation from the acute bleed. Thus, AFS 1 and 2 dogs with anemia is likely to have been experiencing low grade bleeds sub-acutely or chronically prior to their presentation. In this same subset of dogs with non-traumatic hemoabdomen, higher-scoring dogs, if not anemic on presentation, will become anemic in time (typically in 4-hours on serial examination with an active bleed). In contrast to bluntly traumatized dogs that are more often treated medically, this subset of hemoabdomen dogs need resuscitation and emergent laparotomy since they are unlikely to have long-term survival without definitive surgical treatment of the source(s) of bleeding.

Finally, serial FAST examinations for all at-risk for bleeding humans are now considered standard of care in human medicine by the American College of Emergency Physicians; and was the protocol in the JVECC study cited in this blog. AFAST and its applied fluid scoring system may be used initially and serially in other effusive conditions such as right-sided heart failure, dogs with 3rd spacing, forms of peritonitis (infectious, inflammatory, neoplastic), as well as serially in dogs with hemoabdomen as a monitoring (tracking) tool for response to therapy. Through experience, we have found that dogs with bluntly-induced or coagulopathic hemoabdomen rapidly self-tranfuse themselves within 48 hours once the bleeding stops.

As for cats, as a species, they generally cannot survive large volume bleeds and declare themselves non-survivors before making it to veterinary facilities (Lisciandro, Abstract JVECC 2013). A cat post-blunt trauma with a large abdominal effusion is more likely to have a uroabdomen than a hemoabdomen.

For more information, we refer to our textbook Focused Ultrasound Techniques for the Small Animal Practitioner and for additional training at our San Antonio FASTVet Academy or through our online Virtual Classroom Courses.

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