Focused Assessment With Sonography for Trauma Examination Reexamining the Importance of the Left Upper Quadrant View

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1 ORIGINAL RESEARCH Focused Assessment With Sonography for Trauma Examination Reexamining the Importance of the Left Upper Quadrant View Kathleen M. O Brien, MD, Lori A. Stolz, MD, Richard Amini, MD, Austin Gross, MD, Uwe Stolz, PhD, MPH, Srikar Adhikari, MD, MS Article includes CME test Objectives The purpose of this study was to determine the frequency and predominant location of isolated free fluid in the left upper quadrant (LUQ) on focused assessment with sonography for trauma (FAST) examinations of adult patients with trauma presenting to the emergency department. Methods We conducted a retrospective review of adult patients with positive FAST results for free fluid in the abdomen at 2 academic emergency departments. Eligible FAST examinations were reviewed for the presence of fluid in the LUQ and exact location of free fluid within the LUQ. Received September 19, 2014, from the Department of Emergency Medicine, Massachusetts General Hospital, Boston, Massachusetts USA (K.M.O.); and Department of Emergency Medicine, University of Arizona Medical Center, Tucson, Arizona USA (L.A.S., R.A., A.G., U.S., S.A.). Revision requested October 17, Revised manuscript accepted for publication November 10, This work was presented in abstract form at the 2014 American Institute of Ultrasound in Medicine Annual Convention; March 29 April 2, 2014; Las Vegas, Nevada. Address correspondence to Srikar Adhikari, MD, MS, Department of Emergency Medicine, University of Arizona Medical Center, PO Box , Tucson, AZ USA. sriadhikari@aol.com Abbreviations CI, confidence interval; CT, computed tomographic; ED, emergency department; EM, emergency medicine; FAST, focused assessment with sonography for trauma; LUQ, left upper quadrant; RUQ, right upper quadrant doi: /ultra Results A total of 100 FAST examinations with free fluid in the abdomen that met inclusion criteria were identified during the study period. Overall 32 of 100 (32%; 95% confidence interval [CI], 23.5% 41.6%) of patients with positive FAST results were found to have free fluid in the LUQ. Only 6 of 100 (6%; 95% CI, 2.5% 11.9%) patients with positive FAST results had free fluid isolated to the LUQ. Of these 6 patients with isolated LUQ free fluid, none had free fluid isolated to the splenorenal fossa alone; 1 had free fluid isolated to the subphrenic space (above the spleen/below the diaphragm); and 4 had free fluid visible only in the left paracolic gutter/inferior to the spleen. Twentyseven of 32 patients (84%; 95% CI, 69.1% 93.8%) with free fluid anywhere in the LUQ were also found to have fluid in the left paracolic gutter. Conclusions Free fluid isolated to the LUQ occurs in a clinically significant number of adult patients with trauma and positive FAST results. Isolated fluid accumulation was often seen within the left paracolic gutter. Key Words bedside ultrasound; emergency ultrasound; focused assessment with sonography for trauma; free fluid; left upper quadrant view; splenorenal The focused assessment with sonography for trauma (FAST) examination is an integral component of the initial evaluation of adult patients with trauma presenting to the emergency department (ED) with possible intra-abdominal or intra-thoracic injury. 1 The American Institute of Ultrasound in Medicine and American College of Emergency Physicians have jointly published guidelines for the performance of FAST examinations, and the American College of Surgeons has recently adopted the FAST examination into the advanced trauma life support protocol by the American Institute of Ultrasound in Medicine J Ultrasound Med 2015; 34:

2 Several studies support the use of FAST as the initial diagnostic modality for evaluation of patients presenting with blunt or penetrating thoracoabdominal trauma to the ED. 4 6 The FAST examination is performed at the bedside after the primary survey of the advanced trauma life support protocol. It allows for rapid detection of hemoperitoneum or hemopericardium and helps determine the need for emergent surgical intervention. 1 When performing the FAST examination, 4 regions (right upper quadrant [RUQ], left upper quadrant [LUQ], cardiac, and suprapubic views) are routinely evaluated. The equality and necessity of all 4 views have recently been called into question. 7 The most sensitive view in the FAST examination for detecting intraperitoneal free fluid is the RUQ. 1,8 Evidence suggests that free fluid is more often detected in the RUQ than LUQ even with isolated splenic injuries. 9 The importance of adequate LUQ views is uncertain, as free fluid is often seen in the pelvis or Morison pouch regardless of the site of the intra-abdominal injury. 8 Although FAST is a seemingly straightforward examination, the LUQ view is technically more challenging for the novice sonographer than the RUQ view. Adequate LUQ views are difficult to obtain and can require considerable time for a novice sonographer. The objectives of this study were to determine the frequency and predominant location of isolated free fluid in the LUQ on FAST examinations of adult patients with trauma presenting to the ED. Materials and Methods Study Design and Study Setting We conducted a retrospective review of ED patients with positive FAST results for free fluid in the abdomen. The study took place at 2 EDs between July 2011 and May Both EDs have an emergency medicine (EM) residency and an active emergency ultrasound training program. The EM core privileges included the FAST examination, and all EM attending physicians were credentialed to perform FAST examinations. This study was approved by the Institutional Review Board. Study Population and Selection Criteria Inclusion criterion were adult patients (>18 years) with trauma and positive FAST results for free fluid in the abdomen. Exclusion criteria were history of ascites, peritoneal dialysis, and a FAST examination performed for an indication other than blunt or penetrating trauma. Study Protocol Eligible patients were identified through multiple queries of the ED ultrasound image archival system (Q-path; Telexy Healthcare, Port Coquitlam, British Columbia, Canada) for FAST examinations with positive results for free fluid in the abdomen. This database stores all pointof-care ultrasound examinations performed at both EDs, including worksheets detailing indications, findings, and the final interpretation that accompanies each ultrasound examination. Studies were identified by querying worksheets for a physician diagnosis of positive abdominal fluid and by querying quality assurance worksheets for positive FAST examination and false-negative study. Emergency medicine residents and attending physicians with varied point-of-care ultrasound experience performed FAST examinations. The FAST examinations were performed after initial clinical assessment. The examinations were performed with a Z.One Ultra (Zonare Medical Systems, Mountain View, CA) or SonixTouch (Ultrasonix Medical Corporation, Richmond, British Columbia, Canada) system with a low-frequency broadband curvilinear or phased array transducer. Standard teaching at our institution for the FAST examination includes obtaining views of the RUQ, LUQ, pelvis, pericardium, and bilateral hemithoraces, with full interrogation of each region. For the LUQ in particular, the examination entails subphrenic views, splenorenal views, and views of the paracolic gutter with anteroposterior fanning. However, the adequacy of the views obtained in the FAST examinations included in this study was determined by the treating EM physician. All ultrasound examinations performed in the ED were reviewed for quality assurance by emergency ultrasound section faculty. Patients with trauma were simultaneously evaluated by EM residents, attending physicians, and the trauma surgery team. The trauma surgery service determined whether a patient needed an additional imaging study or emergent surgical intervention. All identified ultrasound examinations were reviewed by one of the study investigators and an expert emergency sonologist to confirm the presence of free fluid in the abdomen. Eligible studies were those found to be positive on image review by both reviewers. Focused assessment with sonography for examinations with positive results were specifically reviewed to determine the location(s) of free fluid in the abdomen. Results were considered positive for free fluid if free fluid was seen in any of the 4 traditional FAST views: RUQ, LUQ, pelvis, and pericardium. Free fluid detected in the LUQ was further characterized as located in the splenorenal recess, subphrenic space above the spleen/below the diaphragm, and left paracolic 1430 J Ultrasound Med 2015; 34:

3 gutter inferior to the spleen (Figure 1). Medical records of these patients were also reviewed for demographic information, clinical features, additional diagnostic testing, and hospital courses and to ensure that inclusion and exclusion criteria were met. All FAST studies with positive results were also reviewed for adequacy of LUQ images. Studies were determined to have adequate LUQ view if all 3 images (splenorenal fossa, left paracolic gutter, and subphrenic space) were recorded in a negative LUQ study and if the quality of the images was sufficient for medical decision making. Any study showing LUQ free fluid was deemed adequate even if all 3 views were not obtained. Because of the subjective nature of this adequacy determination, a second blinded expert emergency sonologist reviewed 30% of the studies to assess the adequacy of the LUQ view. Interobserver disagreements were settled by further image review by a third blinded expert emergency sonologist. Both expert sonologists performed more than 2000 point-of-care ultrasound examinations before this study. Outcome Measures The primary outcomes included the frequency of positive FAST examinations with free fluid isolated to the LUQ and the exact location of LUQ free fluid. The secondary outcomes included LUQ image quality and type of intraabdominal injury in patients with isolated LUQ free fluid. Data Analysis Statistical analysis was performed with Stata version 12.1 software (StataCorp, College Station, TX). Continuous data are presented as means and standard deviations, and dichotomous data are presented as percentage frequencies of occurrence. Data for the free fluid location in positive FAST examinations and adequacy of the LUQ view are reported as percentages with 95% confidence intervals (CIs) calculated by the Jeffrey method. 10 Clinical features and final outcomes of patients with and without isolated LUQ free fluid were compared by the Fisher exact test for categorical data (heart rate >100 beats per minute, systolic blood pressure <100 mm Hg, or blood products given during the ED course) and the Kruskal-Wallis test for continuous data (initial heart rate, initial systolic blood pressure, intensive care unit length of stay, and hospital length of stay). Results A total of 405 FAST examinations were reviewed, and 100 examinations met inclusion criteria. The mean age of the patients was 37 (SD, 16) years. Thirty percent were female. The locations of free fluid in the LUQ are summarized in Figure 2. Overall, 32 of 100 (32%; 95% CI, 23.5% 41.6%) patients with positive FAST results were found to have free fluid in the LUQ. Only 6 of 100 (6%; 95% CI, 2.5% 11.9%) patients with positive FAST results had free fluid isolated to the LUQ. Of these 6 patients with isolated LUQ free fluid, none had free fluid isolated to the splenorenal fossa alone; 1 had free fluid isolated to the subphrenic space (above the spleen/below the diaphragm); and 4 had free fluid visible only in the left paracolic gutter/inferior to the spleen (Figures 3 and 4). Twenty-seven of 32 patients (84%; 95% CI, 69.1% 93.8%) with free fluid anywhere in the LUQ were also found to have fluid in the left paracolic gutter. Twenty-six of 32 patients (81%; 95% CI, 65.4% 91.8) with free fluid in the LUQ had other positive FAST views. Of patients with isolated LUQ free fluid, 83% had computed tomographic (CT) findings consistent with isolated splenic injury (Table 1). Figure 1. Free fluid (arrows) in the splenorenal recess (A), subphrenic space above the spleen/below the diaphragm (B), and left paracolic gutter inferior to the spleen (C). J Ultrasound Med 2015; 34:

4 There was no significant difference between patients who had isolated LUQ free fluid and those who did not for the initial heart rate (P=.4), systolic blood pressure (P=.8), Figure 2. Locations of free fluid in the LUQ. incidence of a heart rate greater than 100 beats per minute during the ED course (P =.2), incidence of systolic blood pressure less than 100 mm Hg during the ED course (P>.9), intensive care unit length of stay (P =.6), hospital length of stay (P =.8), or percentages of patients given blood products (P =.2). Fifty-one percent (95% CI, 41.3% 60.7%) of FAST examinations had LUQ views that were deemed inadequate for medical decision making. Eighty-nine percent (95% CI; 77.3% 84.9%) of the studies deemed inadequate were found to have poor or absent subphrenic views. All 6 patients with isolated LUQ free fluid had adequate pelvic views without a decompressed urinary bladder. Discussion Although it is challenging to obtain LUQ images, as demonstrated by more than 50% inadequate LUQ images in our review, this study suggests that it is an essential component of the FAST examination in adult patients with trauma. We found a small but clinically meaningful pro- Figure 3. A, Patient 1: free fluid (arrow) isolated to the left paracolic gutter. B, Patient 2: free fluid (arrow) isolated to the subphrenic space above the spleen/below the diaphragm. C, Patient 3: free fluid (arrow) isolated to the left paracolic gutter inferior to the spleen. Figure 4. A, Patient 4: free fluid (arrow) isolated to the left paracolic gutter. B, Patient 5: free fluid (arrow) isolated to the left paracolic gutter inferior to the spleen. C, Patient 6: free fluid in the subphrenic space (left arrow) and splenorenal fossa (right arrow) J Ultrasound Med 2015; 34:

5 portion of positive FAST examinations to have isolated free fluid only in the LUQ (6%). Therefore, foregoing this view could mean missed injuries in a clinically significant number of patients with trauma. Conventional FAST instruction emphasizes obtaining views of the splenorenal recess and briefly fanning through the left subphrenic space and down the left paracolic gutter. It is widely taught that free fluid is apt to accumulate first in the left subphrenic space and overflow into the splenorenal recess and, finally, down the left paracolic gutter and into the pelvis. 11 Our findings contradict this traditional teaching, which is an assumption made on the basis of CT findings of exudate movement in patients with intra-abdominal abscesses. 12 In our study, free fluid isolated to the splenorenal recess was not found. Our findings demonstrate that free fluid within the LUQ is most frequently seen in the left paracolic gutter. The left paracolic gutter is easy to visualize and teach to novice sonographers. On the basis of our study findings, we recommend focusing on this particular region within the LUQ while teaching the FAST examination. Our findings demonstrate that even EM residents and attending physicians at a level 1 trauma center with a robust ultrasound program have difficulty in obtaining adequate LUQ views despite educational efforts that stress the importance of all 3 LUQ locations. Image review found that more than 50% of LUQ views obtained were inadequate for medical decision making. The subphrenic view was overwhelmingly found to be suboptimal or not obtained. Our findings suggest that limited visualization of the left paracolic gutter and subphrenic views should be emphasized during FAST examination training. Additionally, our findings indicate that most isolated LUQ free fluid was secondary to splenic injury. This finding held true in 83% of the cases, simultaneously reinforcing and calling into question prior knowledge that the location of free fluid in a FAST examination is not indicative of the location of intraabdominal injury. Table 1. Injury Patterns on CT Associated With Free Fluid Isolated to the LUQ on FAST Examinations Patient Injury on CT 1 Grade 3 splenic laceration 2 Grade 5 splenic laceration 3 Right renal laceration, inferior vena cava injury, liver laceration 4 Grade 2 splenic laceration 5 Grade 4 splenic laceration 6 Grade 2 splenic laceration Our study had several limitations, including its retrospective nature, which could have introduced a selection bias. It is, however, our departmental protocol to perform a FAST examination on all patients with trauma and possible intra-abdominal or intra-thoracic injury, thereby minimizing our selection bias. Our study was limited to those positive FAST examinations appropriately archived and by the quality of images archived at the time of clinical assessment. It is possible that some patients who were particularly unstable or critically ill underwent FAST examinations, and images were not saved and were therefore unavailable for analysis. Our quantification of inadequate LUQ views may be an overestimation, in that all examinations reviewed had positive results. If an operator had noted free fluid in another abdominal view before performing the LUQ view, the individual might have been satisfied with less than optimal LUQ views, as medical decision making would have been unchanged by subsequent images. Since a CT scan was not obtained in all patients, it is possible that we have underestimated the incidence of isolated LUQ fluid. Additionally, a substantial number of FAST examinations could have had isolated LUQ free fluid but were not included in the analysis because fluid was not identified secondary to inadequate LUQ views. This study very likely underestimated the number of patients with isolated LUQ free fluid because of the high number of FAST examinations with inadequate LUQ images. Although an analysis was performed to compare patients with isolated LUQ free fluid to others, there was not sufficient power to detect meaningful differences. The other limitation of this study was the small sample size, which could also limit the conclusions that can be reached. In conclusion, free fluid isolated to the LUQ occurs in a clinically significant number of adult patients with trauma and positive FAST results. Isolated LUQ fluid accumulation was often seen within the left paracolic gutter. Adequate LUQ views should be obtained as part of the FAST examination. Special attention should be paid to imaging the left paracolic gutter, as it is the LUQ location most likely to yield a positive finding and can be easily imaged even by a novice sonographer. References 1. Williams SR, Perera P, Gharahbaghian L. The FAST and E-FAST in 2013: trauma ultrasonography overview, practical techniques, controversies, and new frontiers. Crit Care Clin 2014; 30: American College of Emergency Physicians. Emergency ultrasound guidelines. Ann Emerg Med 2009; 53: J Ultrasound Med 2015; 34:

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