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Does This Adult Patient Have Blunt Intra-abdominal Injury? Interview With Daniel K. Nishijima, MD, MAS
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Does This Adult Patient Have Blunt Intra-abdominal Injury? Interview With Daniel K. Nishijima, MD, MAS
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Language: EN.
Segment:0 .
>> Hello and welcome to JAMAevidence, our monthly podcast focused on core issues and evidence-based medicine. I'm David Simel, Professor of Medicine at the Durham Veterans Affairs Medical Center and Duke University. I'm the editor of the Rational Clinical Exam Series, and today we'll be talking to Dr. Dan Nishijima about the diagnosis of blunt intra-abdominal injuries. Dan, could you introduce yourself to our listeners? >> Hi. My name is Daniel Nishijima. I'm an Assistant Professor of Emergency Medicine here at UC Davis.
>> Dr. Nishijima did a review for the Rational Clinical Examination Series, Does This Adult Patient Have a Blunt Intra-Abdominal Injury? Dan, could you tell us what type of patients were the focus of your review? >> Sure. This review is directed for the hemodynamically stable patients with blunt abdominal trauma where there is some question on whether additional testing, such as a CT scan of the abdomen, is being considered. This review is not directed towards enough hemodynamically unstable patients whom a different algorithm is employed.
We see a lot of patients in the ED that fit into this category of hemodynamically stable blunt abdominal trauma, and we often struggle with who should and should not receive an abdominal CT scan. Our goal is to identify all clinically important intra-abdominal injuries, but at the same time utilize CT imaging wisely. We should really be cognizant that the risk for radiation-induced malignancy in a young adult is about 1 in 500, which is not a negligible number. >> What is the prevalence of blunt intra-abdominal injury after abdominal trauma among patients presenting to the emergency department?
>> Well, we pooled the prevalence of intra-abdominal injury in adult ED patients with blunt abdominal trauma among 23 studies totaling over 15,000 patients, and the prevalence for intra-abdominal injury was 13%. There were four studies totaling nearly 5,000 patients that evaluated the outcome measure of clinically significant injuries, such as those requiring intervention, such as surgery or interventional embolization. The prevalence is 4.7%. >> Well, that's a fair number of patients. So what makes proper diagnosis so important when dealing with blunt abdominal trauma?
>> Well, prior studies have demonstrated that missed or delayed diagnoses of intra-abdominal injuries lead to increased morbidity and mortality. Solid organ injuries such as a splenic or liver injury may cause ongoing bleeding, while a hollow viscus injury, such as a missed small or large bowel perforation, may cause leakage of bowel contents into the abdomen and lead to number of complications. Thus, it is crucial to identify clinically important injuries as soon as possible.
>> Well, before we get to a discussion about the useful clinical findings, what about things we assess that actually aren't useful? So what I'm thinking about, for example, is, shouldn't that absence of abdominal pain rule out an injury in most patients? >> Yes. One of the most interesting findings from our study was that abdominal pain after trauma and abdominal tenderness on palpation did not perform well in ruling in or ruling out intra-abdominal injuries. Many clinicians use abdominal tenderness on palpation as a primary decision point to CT or not, and our study suggests that this shouldn't be the case.
We all know that trauma patients are often altered, intoxicated, or have distracting injuries, thus making the abdominal examination not infrequently unreliable. >> Well, how about then describing some of the more useful physical examination findings for diagnosing blunt intra-abdominal injury? >> Well, there are a few physical examination findings that the clinician cannot ignore. First is a seatbelt sign. This occurs when the lap portion of the seatbelt causes bruising over the anterior abdomen after a motor vehicle accident.
So if present on physical examination, the positive likelihood ratio is roughly between 5 to 10. Even with a low pretest probability, the post-test probability with the presence of a seatbelt sign makes it difficult to rule out intra-abdominal injury. Thus, the mechanism of injury is concerning for producing an occult bowel injury, which, even on CT scan, may be difficult to diagnose. Here at UC Davis, we often admit patients with seatbelt sign and persistent abdominal pain for serial abdominal exam, even with a negative CT scan.
Other abdominal examination findings, such as rebound tenderness, guarding, and abdominal distension are much more rare compared to abdominal tenderness alone. However, when present, the positive likelihood ratio ranges from roughly 4 to 7. Two other physical examination findings to pay attention to are, one, low blood pressure or hypertension in the ED; and two, a concomitant femur fracture. These findings had a positive likelihood ratio of 5 and 3, respectively, and thus should raise the clinician's suspicion for intra-abdominal injury.
>> Dan, in your review, you looked at the use of bedside ultrasound, which is now something that emergency medicine physicians all over the country are able to do. Can you please explain the FAST, F-A-S-T ultrasound examination for our listeners and describe its utility in the diagnosis of intra-abdominal injury? >> Sure. The FAST examination stands for the Focused Assessment with Sonography for Trauma, and essentially what it does is we use a low-frequency ultrasound transducer to evaluate for free fluid in abdominal cavity or around the heart.
The FAST examination consists of four views the right and left upper quadrants, the pelvis, and a subxiphoid view of the heart. We included the FAST examination in our review because it was a non-invasive test done at the bedside and can be completed within a few minutes. Essentially, in the ED, we use it as kind of an extension of a physical examination. Our study demonstrated that the FAST examination is the single best test for the valuation of blunt abdominal trauma. Even when we adjusted for the potential for publication bias, the summary positive likelihood ratio was 30, which is great, and a summary negative likelihood ratio was 0.26, which is good.
Thus, if the FAST examination is positive, the clinician essentially should obtain a CT scan, as the risk for intra-abdominal injury is very high. If the FAST examination is negative, it does not rule out into intra-abdominal injury, particularly if your pretest probability is moderately high. However, if the clinicians pretest probability is low, it may decrease the post-test probability enough to avoid CT imaging. >> Well, thanks. Is there anything else you'd like to tell our listeners about the clinical examination for blunt intra-abdominal injury?
>> Yes. It's rather clear that there is not one bedside clinical finding that rules in or rules out intra-abdominal injury, nor does overall clinical suspicion by the clinician rule in or rule out intra-abdominal injury. Thus, it is clear that a combination of findings and potentially the incorporation of the FAST examination will be the key to decreasing CTs for blunt abdominal trauma. >> Thanks, Dan, for talking with us today. More information about this topic is available in the Rational Clinical Examination Series and on our website, JAMAevidence.com, where you can listen to our entire roster of podcasts.
I'm David Simel, and I'll be back with you soon for another edition of JAMAevidence.
