Caudal Edge of the Liver in the Right Upper Quadrant (RUQ) View Is the Most Sensitive Area for Free Fluid on the FAST Exam

Background

The FAST exam is a useful tool in screening for the presence of intraperitoneal free fluid in the setting of trauma. The utilization of ultrasound provides rapid imaging in the trauma bay that can help guide clinical decision making and the necessity for surgical intervention. The FAST exam is comprised of subxiphoid, right upper quadrant, left upper quadrant, and suprapubic views by ultrasound. Previous research has indicated that the RUQ, specifically the hepato-renal space (Morrison’s pouch), is the preferred area for the detection of free fluid.1,2 However, scarce research into the sub-divisions of each view has been performed.

Caudal Edge of the Liver in the Right Upper Quadrant (RUQ) View Is the Most Sensitive Area for Free Fluid on the FAST Exam

Clinical Question

The aim of this study was to determine what specific sub-divided areas of each FAST view were the most sensitive in the detection of intraperitoneal free fluid.

Methods & Study Design

• Design

This was a retrospective cohort analysis.

• Population

All patients who received a FAST exam at a single Level 1 trauma center over an 18-month period.

• Intervention

The RUQ, LUQ, and suprapubic views of the FAST were each subdivided into three additional sections for analysis. Specifically, the RUQ was divided into the hepato-diaphragmatic space (RUQ1), hepato-renal space (Morrison’s pouch) (RUQ2), and the caudal liver tip (RUQ3). The LUQ was divided into the spleno-diaphragmatic space (LUQ1), the spleno-renal space (LUQ2), and the inferior pole of the kidney (LUQ3). The suprapubic area was divided into the lateral sides of the bladder (SP1), posterior bladder and anterior pelvic organ space (SP2), and posterior uterus (in female subjects) (SP3). The subxiphoid view was excluded as the study was only interested in intraperitoneal free fluid.

• Outcomes

Each sub-quadrant of all positive FAST exams was analyzed for the presence of free fluid.

Results

Of the 1,008 FAST scans included in the study, 48 (4.8%) were positive for free fluid. These findings were either confirmed by CT or intraoperatively.
Of the positive FAST exams, 32 (66.7%) were positive in the RUQ, 17 (35.4%) were positive in the LUQ, and 23 (47.9%) were positive in the suprapubic region.
Of the positive RUQ scans, 30 (93.8%) were positive in RUQ3, 27 (84.4%) in RUQ2, and 5 (15.6%) in RUQ1.
Of LUQ scans, 11 (64.7%) were positive in LUQ1, 10 (58.8%) in LUQ2, and 4 (23.5%) in LUQ3.
In the SP view, 15 (64.7%) were positive in SP1, 9 (58.8%) in SP2, and 7/9 (77.7%) in SP3.
No correlation was found between quadrants.

Strength & Limitations

This was a simple, well done study that provides useful information on the FAST exam. The study featured a relatively small sample size of 48 positive FAST exams. There is a potential that in the time between a FAST exam and further intervention (CT or OR) further bleeding could have occurred, thus lowering the sensitivity of the FAST. The authors struggled to make conclusions regarding the suprapubic view between sexes due to a small sample size of positive SP views.

Authors Conclusion

The caudal tip of the liver (RUQ3) is the most sensitive area for the detection of free fluid on FAST exam.

Our Conclusion

The FAST exam can be an extremely useful tool at the bedside or in the setting of trauma. All areas of the FAST should be properly viewed, with particular emphasis on the caudal tip of the liver. It is important to note that many FAST exams only showed free fluid in one area of one quadrant while showing no free fluid elsewhere, therefore it is important to assess all three areas in every view to increase the sensitivity of the FAST exam.

The Bottom Line

Despite previous emphasis on Morrison’s pouch, the caudal liver tip is a more sensitive indicator of intraperitoneal free fluid and should be properly visualized on every FAST exam.

Authors

This post was written by Oliver Marigold, MS4 at UCSD School of Medicine, Charles Murchison MD and Amir Aminlari MD.

References

Von Kuenssberg Jehle, D., Stiller, G. & Wagner, D. Sensitivity in detecting free intraperitoneal fluid with the pelvic views of the FAST exam. The American Journal of Emergency Medicine 21, 476–478 (2003).
AIUM Practice Guideline for the Performance of the Focused Assessment With Sonography for Trauma (FAST) Examination. Journal of Ultrasound in Medicine 33, 2047–2056 (2014).
Lobo, V. et al. Caudal Edge of the Liver in the Right Upper Quadrant (RUQ) View Is the Most Sensitive Area for Free Fluid on the FAST Exam. WestJEM 18, 270–280 (2017).

February 19, 2020July 21, 2020

Case # 17: Par for the Course

An 80 year old man presents to a rural emergency room at 3am with abdominal pain. His past medical history is significant for mild hemophilia A. Six hours prior to arrival, he was driving a golf cart when he struck a pole and the steering wheel hit his stomach.

He initially had no symptoms but began to have abdominal pain while trying to sleep. He also became nauseated and vomited once. He eventually called EMS and was brought to the ER. On arrival, his vitals are as follows.

Vitals: T: 90.7, HR: 108, BP: 74/48, RR: 28, SpO2 98 on 4L

He is alert, oriented and his only complaint is abdominal pain. A FAST exam was done. What do you see? What are your next steps?

Answer and Learning Points

Answer

Although the quality of images is lacking due to the urgency of the situation and the patient's body habitus, the first image (RUQ) does not show obvious free fluid. The following images (suprapubic and LUQ) clearly show free fluid in the abdomen.

An emergent evacuation of the patient to a level 1 Trauma service was requested. Patient was transfused with two units of O blood. Due to his history of hemophilia A, the patient was also given factor VIII to 100% repletion. The patient was taken to the OR at the level 1 trauma center where he was found to have a greater omental bleed and was successfully treated with clot evacuation and laceration repair. He was placed on a factor VIII drip postop.

Learning Points

- Per ATLS guidelines, a hypotensive patient with a + FAST and no other signs of bleeding warrants immediate surgical exploration.
- In a 2018 meta-analysis, a positive FAST has a sensitivity of 68% and a specificity of 95%. Therefore a negative FAST does not rule out the disease, but a positive fast in the correct clinical sitting (such as this) does rule in hemoperitoneum(1).
- Hemophiliac patients require factor VIII replacement to 100% in the setting of major trauma, which is typically 50 IU/kg(2).

Author

Feigenbaum, Adam, PA-C. Emergency Medicine Fellow, Naval Medical Center San Diego.

Sukhdeep Singh, MD. Clinical Faculty, UCSD Department of Emergency Medicine. Director of POCUS, El Centro Regional Medical Center.

References

Stengel D et al. Point-of-care ultrasonography for diagnosing thoracoabdominal injuries in patients with blunt trauma. Cochrane Database Syst Rev. 2018. Dec 12;12
Guidelines for Emergency Department Management of Individuals with Hemophilia and Other Bleeding Disorders. https://www.hemophilia.org/Researchers-Healthcare-Providers/Medical-and-Scientific-Advisory-Council-MASAC/MASAC-Recommendations/Guidelines-for-Emergency-Department-Management-of-Individuals-with-Hemophilia-and-Other-Bleeding-Disorders. December 5, 2019

September 18, 2017July 22, 2020

Case # 6: Not Your Average Syncope

A 25 year old female presents to the emergency department with acute abdominal pain and a syncopal episode. She notes a positive home urine pregnancy test 1 week ago. She appears mildly uncomfortable with a tender abdomen. A bedside ultrasound is performed, a clip is shown below. What are the findings of the ultrasound clip and what is your diagnosis?

Vitals: T 98.7 HR 120 BP 95/72 RR 20 O2 98% on RA

Image courtesy of Elizabeth Owen, MD

Answer and Learning Point

Answer

The ultrasound clip demonstrates a large amount of free fluid between the spleen and the diaphragm. There is also a sliver of echogenic material above the capsule of the spleen suggestive of clotted blood. Morison’s pouch (not shown) was also noted to be significantly positive for free fluid. Given the patient’s unstable vitals and the clinical history, this was concerning for a ruptured ectopic pregnancy. OB was consulted immediately and the patient was taken to the OR. The diagnosis of ruptured ectopic pregnancy was confirmed during laparotomy. The patient did well.

While the FAST exam has traditionally been used in trauma, there has been increasing use to diagnose intra-abdominal bleeding as a source of hypotension in medical patients. Specifically with regards to ectopic pregnancy, data has suggested that positive free fluid in Morison’s pouch is highly predictive of operative intervention with a positive likelihood ratio of 112 (Sens 50%, Spec 99.5) [1]. A retrospective study in 2001, looking at emergency medicine physician performed ultrasound, demonstrated that identifying patients with a suspected ectopic pregnancy and free fluid in Morison’s pouch decreased the time to diagnosis and treatment [2].

Learning Points

- All women of childbearing age presenting with abdominal pain and syncope should be presumed to have a ruptured ectopic pregnancy until proven otherwise
- Transabdominal ultrasound to evaluate for free fluid should be utilized by the emergency physician in cases of suspected ruptured ectopic pregnancy to assist with risk stratification and rapid diagnosis
- As in trauma patients, evaluation for free fluid should be performed with the patient supine (or preferably Trendelenburg position as this increases the sensitivity of identifying free fluid in Morison’s pouch [3])
- A curvilinear (preferred) or phased-array probe should be used to evaluate the abdomen for free fluid and it is critical to completely visualize the most inferior portion of Morison's Pouch, including the caudal tip of the liver & inferior renal pole, as this is where free fluid will collect first
- A positive pregnancy test and positive free fluid in Morison’s pouch is essentially diagnostic of a ruptured ectopic pregnancy (though ruptured splenic artery aneurysm should also remain on your differential)

Author

This post was written by Michael Macias, MD, Ultrasound Fellow at UCSD.

References

1. Moore C, Todd WM, O’Brien E. Free Fluid in Morison’s Pouch on Bedside Ultrasound Predicts Need for Operative Intervention in Suspected Ectopic Pregnancy. Acad Emerg Med. 2007; 14(8):755-8.
2. Rodgerson JD, Heegaard WG, Plummer D, Hicks J, Clinton J, Sterner S. Emergency department right upper quadrant ultrasound is associated with a reduced time to diagnosis and treatment of ruptured ectopic pregnancies. Acad Emerg Med. 2001; 8:331–6.
3. Abrams BJ, Sukumvanich P, Seibel R, Moscati R, Jehle D. Ultrasound for the detection of intraperitoneal fluid: the role of Trendelenburg positioning. Am J Emerg Med. 1999;17:(2)117-20.

July 16, 2017July 22, 2020

Does This Adult Patient Have a Blunt Intra-abdominal Injury?

Background

Trauma is the leading cause of death in those younger than 45 years in the United States. Around 80% of injuries are due to blunt trauma with 20% involving penetrating trauma. It is blunt trauma, however, that carries substantial diagnostic challenges due to complex injury patterns and difficult management strategies. This paper sets out to review and summarize the comparisons of different techniques in diagnosis of intra-abdominal injury via physical exam findings, laboratory values, and imaging including bedside ultrasound.

Does This Adult Patient Have a Blunt Intra-abdominal Injury?

Clinical Question

How accurate and reliable are existing symptoms, signs, laboratory tests and bedside imaging studies at diagnosing intra-abdominal injury following blunt abdominal trauma?

Methods & Study Design

Population
- The study analyzed 12 papers that assessed clinical examination and 22 papers to assess role of FAST in identifying intra-abdominal injury. Sample sizes ranged from 117 to 3435 patients. All studies defined inclusion criteria as adult patients with any blunt abdominal trauma except for 2 studies that included only adult patients in motor vehicle collisions.
Intervention
- This particular paper focused on the likelihood ratios of various approaches in predicting intra-abdominal injury including: physical exam findings (i.e rebound tenderness, abdominal distention, guarding, seat belt sign, and hypotension), laboratory tests (i.e. base deficit, hematuria, elevated transaminases and anemia), and FAST examination.
Outcomes
- Researchers measured specificity, sensitivity, positive likelihood and negative likelihood of the various physical exam, laboratory, and imaging findings associated with blunt trauma.
Design
- This is a meta-analysis of numerous prospective studies looking at blunt abdominal trauma.
Excluded
- The publishers chose to include studies that were prospective, with consecutive enrollment and blinding, and included a reference standard (i.e. abdominal CT, DPL, laparotomy, autopsy, or clinical course to detect intra-abdominal injury or hemoperitoneum).

Results

Strengths & Limitations

Strengths
- Analyzed the biggest publications from top-trauma centers focusing on strength of statistical analysis.
- Created subcategories of studies that focused on FAST in order to ascertain if any of the information was skewed.
Limitations
- This is a 2012 study that only focused on papers older than 2007, excluding any new techniques and standards as well as imaging advancements of the last decade.
- They did not review studies for clinical outcome, so cannot draw conclusions regarding how change in bedside exam and procedures impact patient care post diagnosis.
- As with all large meta-analysis studies there is always risk of significant heterogeneity from varying study inclusion/exclusion criteria making generalizability complex.

Author's Conclusions

“Bedside ultrasonography has the highest accuracy of all individual findings, but a normal result does not rule out an intra-abdominal injury. Combinations of clinical findings may be most useful to determine which patients do not require further evaluation, but the ideal combination of variables for identifying patients without intra-abdominal injury requires further study.”

Our Conclusions

Overall, this paper reinforces the strength of bedside ultrasonography (adjusted positive LR of 30) as a diagnostic tool of intra-abdominal injury following blunt trauma compared to physical exam and laboratory findings. This reinforces ultrasounds role as the best tool to "rule-in" an intra-abdominal injury. However, it also elucidates a relatively poor sensitivity of the FAST exam, making it a poor tool to "rule-out." This is important as it urges physicians to not rely solely on a negative FAST exam when ruling out intra-abdominal injury but consider other factors including clinical gestalt, mechanism of injury, physical exam and laboratory work up.

Additionally, to better understand the magnitude of this paper's findings it is important to known what a likelihood ratio really tells us. The following image is a quick way to think about likelihood ratios. A positive likelihood ratio of 2 should increase your probability of disease ( resulting in your post test probability) by 15%, 5 by 30% and 10 by 45%. Likewise a negative likelihood ratio of 0.5 should decrease your probability of disease by 15%, 0.2 by 30% and 0.1 by 45%.

The Bottom Line

Bedside ultrasonography is a highly specific diagnostic tool to rule in intra-abdominal injury following blunt trauma but should be used in conjunction with clinical gestalt, physical exam findings and laboratory values when ruling out injury.

Authors

This post was written by Olga Miakicheve, MS4 at UCSD. It was edited by Michael Macias, MD.

References

1. Simel, D. (2012). Does This Adult Patient Have a Blunt Intra-abdominal Injury?. JAMA, 307(14), 1517. doi:10.1001/jama.2012.422

July 4, 2017July 22, 2020

FAST Ultrasound Examination as a Predictor of Outcomes After Resuscitative Thoracotomy

Background

The emergency resuscitative thoracotomy (RT), aka The ED Thoracotomy, is a procedure performed as a last-ditch effort during resuscitation of a patient in traumatic arrest or impending traumatic arrest. Unfortunately despite physicians’ best efforts, outcomes for this procedure are generally poor. The largest review of outcomes after RT performed in the emergency department found an overall survival of 7.4% (8.8% for penetrating injury, 1.4% for blunt injury), with good neurological outcomes present in 92.4% of surviving patients [2]. Furthermore, given the lack of high quality evidence on this procedure, there are no universal guidelines that exist to determine optimal candidates [3,4]. Point-of-care ultrasound has become a core adjunct in evaluation of the trauma patient, however there is minimal data evaluating its utility in determining which trauma patients may benefit from RT [5].

FAST Ultrasound Examination as a Predictor of Outcomes After Resuscitative Thoracotomy: A Prospective Evaluation

Clinical Question

Can the Focused Assessment Using Sonography for Trauma (FAST) predict survival after a RT in patients presenting to the emergency department in traumatic cardiac arrest?

Methods & Study Design

Population
- All penetrating trauma patients with absent vital signs and blunt trauma patients with a loss of vital signs en route or in the resuscitation bay that underwent RT.
Intervention
- A FAST exam was performed just prior to RT to assess for the presence or absence of a pericardial effusion and cardiac motion.
Outcomes
- Survival to Discharge or Organ Donation
Design
- Prospective, observational study performed at a single academic level-1 trauma center
Excluded
- Patients who were taken directly to the OR for an emergent or urgent thoracotomy were excluded.
- Patients who did not have a FAST exam performed prior to RT were excluded from analysis

Results

- 223 patients underwent RT, 187 underwent analysis (36 had no FAST performed)
  - Primary Outcome
    - Survival: 3.2%
    - Organ Donation: 1.6%

Strengths & Limitations

Strengths
- First large, prospective observation study on emergency RT
- Sensitivity analysis performed to include patients who had inadequate views obtained
Limitations
- Study performed at a high-volume, single academic level-1 trauma center with which may skew generalizability
- Residents who had formal training in the FAST exam performed all ultrasound scans. Many emergency medicine physicians are not credentialed in ultrasound or FAST examination

Author's Conclusions

"In summary, for the patients that arrived to hospital and underwent a FAST examination, all survivors and organ donors had visible cardiac motion. If no cardiac motion or pericardial effusion was seen, the survival was zero. Ultrasound was, therefore, able to effectively identify those patients who had the potential to survive the RT and discriminate them from those who did not. Utilizing ultrasound would have resulted in the avoidance of a significant proportion of thoracotomies which were ultimately found to be futile.”

Our Conclusions

This is a well done study examining the utility of the FAST exam in identifying which patients will potentially benefit from emergency RT. One may look at the primary outcomes of this study and think that the very low overall survival rate (3.2%) does not jive with previously reported studies. However, it is important to note that during the study period, 21 patients who had a penetrating cardiac injury and went straight to the OR for thoracotomy, were excluded. All of these patients survived. If we were to incorporate this number into the the final analysis, survival would be ~13% which fits better with previous data. But that isn’t the point of this study. The big question that I feel is appropriately answered is which patient population can we safely avoid undertaking an emergency RT, knowing it is futile. While resource utilization for a procedure of this magnitude may be less burdensome at an academic level-1 trauma center, performing a RT in an emergency department where this is rare occurrence requires a much larger undertaking by the staff. The new data from this study, demonstrates that patients who did not have cardiac motion or a pericardial effusion on initial FAST had a zero survival rate. This is practice changing, especially for providers who rarely perform this procedure. If an experienced trauma team performing this procedure had zero survival rate in patients with no cardiac motion or pericardial effusion, it is safe to say that a provider with less experience will not perform better. Furthermore, having real time data to share with the entire resuscitation team during a traumatic arrest can provide closure to the team and a sense that performing any further heroic procedures is futile.

The Bottom Line

The FAST exam is a critical adjunct in traumatic patients and should be applied to all cases of traumatic arrest in order to determine the utility of performing an emergency RT.

References

1. Inaba K, e. (2017). FAST ultrasound examination as a predictor of outcomes after resuscitative thoracotomy: a prospective evaluation. - PubMed - NCBI . Ncbi.nlm.nih.gov. Retrieved 4 July 2017, from https://www.ncbi.nlm.nih.gov/pubmed/26258320
2. Rhee PM, e. (2017). Survival after emergency department thoracotomy: review of published data from the past 25 years. - PubMed - NCBI . Ncbi.nlm.nih.gov. Retrieved 4 July 2017, from https://www.ncbi.nlm.nih.gov/pubmed/10703853
3. Seamon MJ, e. (2017). An evidence-based approach to patient selection for emergency department thoracotomy: A practice management guideline from the Eastern Association ... - PubMed - NCBI . Ncbi.nlm.nih.gov. Retrieved 4 July 2017, from https://www.ncbi.nlm.nih.gov/pubmed/26091330
4. Burlew CC, e. (2017). Western Trauma Association critical decisions in trauma: resuscitative thoracotomy. - PubMed - NCBI . Ncbi.nlm.nih.gov. Retrieved 4 July 2017, from https://www.ncbi.nlm.nih.gov/pubmed/23188227
5. Moore EE, e. (2017). Defining the limits of resuscitative emergency department thoracotomy: a contemporary Western Trauma Association perspective. - PubMed - NCBI . Ncbi.nlm.nih.gov. Retrieved 4 July 2017, from https://www.ncbi.nlm.nih.gov/pubmed/21307731