Background:
Biliary disease is a common presentation in the Emergency Department which is typically evaluated using ultrasound. Point-of-care Ultrasound (POCUS) of the gallbladder by emergency physicians has been demonstrated in previous literature to be both fast and accurate in diagnosing patients with cholelithiasis and cholecystitis. However, surgeons are hesitant to accept of the results of POCUS studies before taking patients to the OR without confirmatory imaging. This is understandable. By taking patients to the OR, surgeons are exposing them to risk and cost. But performing additional imaging (often radiology performed gallbladder ultrasound) itself adds time and cost the patient's ED stay. If we pull this thread further, we can hypothesize that creating delays in the ED can result in increased morbidity for the patient as well as delay the care of further downstream patients.
So, this begs the question of how we can most efficiently utilize our imaging resources. Does the ED need to scrap the idea of Gallbladder POCUS and accept delays in diagnosis in favor of a comprehensive imaging study? Or has gallbladder POCUS been demonstrated sufficiently to be a reliable test and surgeon behavior relative to test need to be changed? The goal of this study is to evaluate the ability of gallbladder POCUS to accurately predict the need for cholecystectomy, thus allowing surgeons to confidently operate based on POCUS findings.
Study Methods Summary:
Population
Retrospective Review of adult patients (>18 years old) in the ED over 18 months who received biliary POCUS by privileged providers.
Intervention
Gallbladder POCUS evaluating for the following items:
- Presence/absence of gallstones
- Pericholecystic fluid
- Common bile duct visualization
- Gallbladder neck
- Gallbladder wall thickening
- Sonographic Murphy's sign
Comparison
Cholecystectomy was considered the gold standard comparator
Outcome
- Primary: Diagnostic performance of POCUS to determine need for cholecystectomy
- Secondary: Evaluate parameters predictive of the need for cholecystectomy
Results:
The study authors identified 283 patients who received gallbladder POCUS in the ED. A fraction of these patients were eventually referred for surgery evaluation and a fraction of the patients referred for a surgery consult underwent cholecystectomy. The vast majority of these patients received both a POCUS study as well as a radiology study. Based on this cohort, the study authors report in the text of their results the following findings:
Presence of Gallstones
- Sensitivity: 55% (40-70%, 0.95 CI)
- Specificity: 92% (87-95%, 0.95 CI)
- Odds Ratio: 13.141 (5.59-30.89, 0.95 CI)
Gallbladder Wall Thickening
- Sensitivity: 18% (9-33%, 0.95 CI)
- Specificity: 98% (95-99%, 0.95 CI)
- OR: 4.815 (1.33-17.438, 0.95 CI)
Sonographic Murphy's Sign
- Sensitivity: 16% (7-30%, 0.95 CI)
- Specificity: 95% (92-97% 0.95 CI)
- OR: 2.675 (0.625-11.485, 0.95 CI)
Length of Stay in the ED
- POCUS: 309 min
- Radiology: 433 min
Conclusions
I find this an interesting study that takes a unique spin on gallbladder POCUS. Previous studies have compared the sensitivity and specificity of POCUS studies using surgical pathology or radiology studies as the gold standard. While this is helpful for establishing the basis for doing gallbladder POCUS, it is not ultimately a patient focused outcome. This study uses an outcome that matters to patients as the gold standard. Do I need to go to the OR to get my gallbladder out - how well does the POCUS study predict that?
There are many benefits that this study provides to the compendium of gallbladder POCUS literature. The first we already mentioned. It shows that gallbladder POCUS is highly specific when predicting the need for cholecystectomy. Another aspect of this study that I find particularly useful is the fact that it breaks down the gallbladder POCUS study into its individual components and evaluates how well each of them each of them perform. The presence of stones is the most highly predictive of cholecystectomy followed by gallbladder wall thickening.
The study does have some limitations. The authors share their list at the end of the discussion. But two major limitations that I find with this study is its retrospective design and the lack of discussion about the radiology ultrasound findings. The authors mentioned that all but two patients who underwent cholecystectomy had both POCUS and radiology studies. But there is no further discussion about how these two studies compare. While an argument can be made that this wasn't the primary focus of the paper, it certainly leaves open the opportunity for a future study to explore how POCUS and radiology studies performed in short succession compare.
Final Verdict
Based on this paper, it seems that gallbladder POCUS in the hands of skilled operators has evolved to the point where it can serve as a standalone test to help inform surgeons when making the decision to go to the OR. For my fellow ED colleagues, you can feel confident in your study. And for the surgeons, when a POCUS study is performed on straight forward patients, look at the images and have a conversation with the ED physician. You may not need to reflexively order a duplicate test.
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