SGEM#398: Another Ab Gets BUSED – POCUS in the ED for Biliary Disease

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Date: March 22, 2023

Reference: Hilsden et al. Point of care biliary ultrasound in the emergency department (BUSED) predicts final surgical management decisions. Trauma Surg Acute Care Open 2022

Guest Skeptic: Dr. Casey Parker is a Rural Generalist that includes in his practice emergency medicine, anesthesia, and critical care. He is also now a fully-fledged “sonologist”. Casey currently splits his time between Broome, a small rural hospital in the remote Kimberley region of Western Australia, and a large tertiary ED in sunny Perth. He has been on the SGEM#369, SGEM#326 and SGEM#217.

Case: A forty-year-old woman presents to the emergency department (ED) complaining of epigastric pain and nausea for 24 hours. The junior doctor has performed physical examination and blood work. She has some right upper quadrant (RUQ) tenderness on palpation and an elevated C-reactive protein (CRP) of 42. Her white blood cell count and liver function tests are normal.

The very efficient junior doctor has arranged for a formal ultrasound, but this will be done later this afternoon, after six hours fasting. As luck would have it the admitting surgeon is currently in the ED seeing another patient.

The supervising ED physician has been to a few training courses and is keen to try out his new sono-skills. This seems like a good case to try and decide if this patient has significant biliary disease such as acute cholecystitis or an impacted gallstone. A focused Biliary US in the ED (BUSED) may be all that is required to guide the surgeon’s decision-making for this patient. Do they need surgery, an ERCP or just analgesia and non-operative care?

Background: The SGEM has reviewed the use of point of care ultrasound (POCUS) for a variety of conditions in the ED. This includes using ultrasound for small bowel obstructions (SGEM#373), shoulder dislocations (SGEM#288), appendicitis (SGEM#274), endotracheal tube placement (SGEM#249), retinal detachments (SGEM#245), skull fractures (SGEM#124), acute heart failure (SGEM#119), renal colic (SGEM#97), acute abdominal aneurysms (SGEM#94) and lumbar punctures (SGEM#41). One use of POCUS we have not covered yet is for diagnosing acute biliary disease.

Ultrasound is usually the first line imaging modality for diagnosing acute biliary disease. As demonstrated in the list of SGEM episodes, ED clinician performed POCUS has been increasing in popularity over the years. Many small trials have compared the accuracy of POCUS to the “gold standard” of “Radiology-performed ultrasound”.

The literature on POCUS for diagnosing acute biliary disease tends to compare the diagnostic accuracy of the sonography in each department. However, little is known about the actual decision-making process after POCUS evaluation.

Clinical Question: When compared to point-of-care ultrasound, what is the value of formal radiology-performed ultrasound in terms of the surgical decision-making in acute biliary disease?

Reference: Hilsden et al. Point of care biliary ultrasound in the emergency department (BUSED) predicts final surgical management decisions. Trauma Surg Acute Care Open 2022

Population: Adult ED patients 18 years of age or older with abdominal pain who the EM physician felt they had biliary disease after performing a history, physical examination, and POCUS
- Excluded: If surgery was completed prior to formal ultrasound imaging, failure to gain consent or age less than 18 years.
Intervention: Surgical decision (offer surgery, ERCP/MRCP or no surgery) based upon the clinical, laboratory and POCUS data. The BUSED scans were performed by one of 11 specifically trained ED physicians. There were 20 surgeons 3 acute care, 4 colorectal, 4 hepatobiliary, 3 surgical oncology and 3 MIS/bariatric.
Comparison: Surgical decision made after formal radiology ultrasound (RUS).
Outcome:
- Primary Outcome: The primary outcome was the percentage of patients in which the management changed after RUS was performed.
- Secondary Outcomes: Clinical decisions based on surgeon subspecialty, biochemical markers, vital signs, and patient demographics.
Type of Study: Observational, prospective cohort study performed at a tertiary care centre study in London, Ontario, Canada

Authors’ Conclusions: “This prospective study has shown that in the vast majority of cases the additional information afforded by formal RUS does not alter clinical management. Point of care biliary ultrasound has been demonstrated to be reliable in the diagnosis of acute biliary disease and offers a safe and efficient diagnostic pathway for patients presenting in the emergency room.”

Quality Checklist for Observational Study:

Did the study address a clearly focused issue? Yes
Did the authors use an appropriate method to answer their question? Yes
Was the cohort recruited in an acceptable way? Yes
Was the exposure accurately measured to minimize bias? Yes
Was the outcome accurately measured to minimize bias? Yes
Have the authors identified all-important confounding factors? Unsure
Was the follow up of subjects complete enough? Yes
How precise are the results? Pretty good
Do you believe the results? Yes
Can the results be applied to the local population? Unsure
Do the results of this study fit with other available evidence? Yes
Funding of the Study? No conflicts of interest declared

Results: The recruited 103 consecutive patients of which 100 were included in the analysis. The mean age was 50 years. The decision was to admit 68 patients for surgery, 21 for duct clearance (ERCP/MRCP) and 11 for no surgery.

Key Result: The surgical plan was not changed often after a formal ultrasound was performed.

Outcome:
- Primary Outcome: The initial plan based upon the ED POCUS was changed 10% of the time after RUS was performed. See the alluvial diagram.

Secondary Outcomes: Clinical decisions based on surgeon subspecialty, biochemical markers, vital signs, and patient demographics.

1. Surgical Decision Making: The crunch point in this trial is based on surgical decision-making. It is difficult to separate the surgeon’s decision based on POCUS vs. RUS when the surgeon would have known that the patient was going to have both, no matter what they decided. It is kind of a Schrodinger’s Cat scenario. A more conservative surgeon who did not have high confidence in ED-performed US prior to the trial may behave in a more relaxed manner given that they would ultimately have access to a formal US prior to any actual intervention. They could have separated some of these issues out and done an RCT, providing the surgeon with a report but not identify if it was generated by POCUS or RUS. Then, the researchers could follow these patients along clinically to see if there was a patient-oriented outcome difference. This may have been more difficult to get ethics approval.

2. External Validity: This is a small study performed at a single, tertiary university affiliated hospital in Canada. The surgical decision making in this hospital may not reflect practice in in differently-sized Eds or in different regions. So, whilst this trial is useful, I would want to repeat it at a large scale in other healthcare system and hospital locations (urban, community, or rural) before stating that it is a truly valid strategy. It is also important to note that the 11 emergency physicians performing the POCUS were fellowship trained in POCUS.

3. Difference between POCUS and RUS for Acute Biliary Disease: At the end of the day, this is a comparison between US vs US. So why would there be a difference? The answer is probably around the experience of the operator and the detection of subtle gallstones in the neck of the gall bladder or common bile duct. These can be really tricky and there are a few trials that have shown that a sonographers personal sensitivity for these stones goes up with experience.

Rickes, et al (2006) showed that experienced sonographers (>10,000 scans) were twice as likely to detect CBD stones than novice (<2000 scans). So, maybe it should be a comparison not between POCUS and formal radiology US, but between novice and more advanced sonographers?

It is nice to remove the inter-departmental conflict, as this is not really about ED vs. Radiology. There is an unfortunate, large amount of POCUS literature where small case series attempt to compare ED vs. Rads scans, it’s not a true dichotomy. I believe that an experienced ED doc would be as good as any radiologist given what we know. After all the stone still exists no matter who is holding the probe.

4. Selection Bias: It is possible there was some selection bias in this study design as patients were only included if the treating Emergency physician felt that the diagnosis was a “biliary disease” after clinical, biochemical and POCUS examination. So, we have already selected a group of patients where the diagnosis was already reasonably clear to the surgeon. It is not that surprising that in this group the EP doing POCUS got it right 90% of the time.

It may be useful to know what the role of biliary POCUS is in less selected patients. eg. those with “upper abdominal pain” or “right side abdominal pain” at triage and include them all in the trial – because that is how patients present… our patients don’t come with simple labels on their files! The true value of POCUS may be in finding the patients where pain is attributed to gallstones, and then no biliary abnormality is found on POCUS thus forcing the ED team to rethink their diagnosis?

5. Baseline Differences: Although this is not a randomized trial it is important to look at the baseline characteristics of each group and ask, “are we looking at the same people in each group?”

There was a big difference in the baseline bilirubin level between groups. This makes sense. If you are jaundiced, then we know that there is a much higher likelihood of having a stone (or another lesion) obstructing the biliary tree. These are potentially sicker patients; they need comprehensive CBD imaging which BUSED is not really going to achieve.
So maybe these patients are not the ones that we should be including in the trial of BUSED. It is unlikely that a surgeon will manage them on any ultrasound alone, they are going to ask for either an MRCP or ERCP to sort out the obstruction before considering surgery or conservative care.
This trial has excellent GRANULAR data on the patients where the treatment decision changed because of the RUS- mostly it came down to the difficulty in imaging the CBD accurately
In my experience as a trained SONOLOGIST – the CBD and distal stones are tough to find on many patients. It takes time and technique which may not be the best use of the ED doctors time if they know that the patient already is jaundiced?

Dr. Rob Leeper

We are fortunate to have Dr. Rob Leeper one of the authors of this study and friend of the SGEM on the show. Here are his comments on our critical appraisal on how to apply the study.

Dr. Rob Leeper

Radiology based US is not as available as you would think in a publicly funded health care system (after midnight, after 5 pm, week days.. as an outpatient you can wait weeks).

One vert simple binary US finding is all that is required to make a surgical decision (presence of absence of gall stones.. exactly analogous to + or – fluid in FAST)

While many urgently presenting patients may have US needs that are complex, there is a very common patient presentation where BUSED applies:

a) A good clinical story for biliary pain (meal associated severe pain in right upper quadrant and into back)

b) A reassuring set of labs that make bile duct pathology unlikely (normal bilirubin and normal liver enzymes)

In this patient, the only thing a surgeon needs to know from the US is whether or not there are stones. If there are not then surgery is off the table. If there are, then the remainder of our decision making about intervention is independent of the US findings and hinges entirely on factors like patient fitness, or availability etc. In other words, the ball is in our court. A huge key for EM providers is to be able to get a patient undeniably “into the surgeon’s court” and this paper demonstrates that for one very common EM presentation, a simply binary bedside test can achieve that degree of certainty.

Comment on Authors’ Conclusion Compared to SGEM Conclusion: We generally agree with the authors’ conclusions. This study does show that in this hospital system ED-performed biliary US by fellowship trained emergency physicians was sufficient to guide surgical decisions in 90% of cases. If we were to exclude the patients with biochemical jaundice, then even more cases would have been adequately imaged with ED-US.

However, this study would need to be replicated on a larger scale in different ED systems to make a recommendation about the role of ED performed US vs radiology scans.

SGEM Bottom Line: In non-jaundiced patients with suspected acute biliary disease, an emergency physician trained in biliary US can correctly inform surgical decision-making in most cases.

Case Resolution: The ED physician performs a focused biliary ultrasound which shows a gallbladder full of stones, some gallbladder wall thickening and a positive sonographic Murphy’s sign. The team can make a diagnosis of acute cholecystitis and refer to the inpatient surgical team and commence antibiotics.

Dr. Casey Parker

Clinical Application: ED doctors can and should be trained in the use of biliary US to help guide their diagnosis in the work up of patients with abdominal pain. They do need to consider the clinical context and receive appropriate training to make accurate and timely diagnosis. This would be like other medical conditions where we rarely use only one data point to inform care.

What Do I Tell My Patient? Your ultrasound, in combination with the blood tests and clinical picture all suggest that you have an acute gallbladder inflammation – this is usually treated with pain medicine and antibiotics, some patients do need to undergo surgery to remove their gallbladder. We will discuss the findings with our excellent Surgical colleagues who will take good care of you and discuss the plan further.

Keener Kontest: There were so many people who had the correct answers to the last keener question. The person who answered correctly first was Dr. Steffen Kerkhoff an Anesthesiologist and EMS Physician from Germany. He knew Igel means a hedgehog in the german language.

Listen to the SGEM podcast to hear this weeks’ question. Send your answer to TheSGEM@gmail.com with “keener” in the subject line. The first correct answer will receive a cool skeptical prize.