Date: December 16th, 2019  

Reference: Moore et al. Imaging in Suspected Renal Colic: Systematic Review of the Literature and Multispecialty Consensus. Annals of EM, JU, and JACR 2019.

Dr. Chris Moore

Guest Skeptics: Dr. Christopher Moore is an Associate Professor of Emergency Medicine a Yale School of Medicine. He is also the Chief for the Section of Emergency Ultrasound and Director of the Emergency Ultrasound Fellowship.

Dr. Kevan Sternberg is an Associate Professor of Urology at the University of Vermont Medical Center.

This is an SGEM Xtra and is a result of a paper that was published in three journals (Annals of EM, Journal of Urology and Journal of the American College of Radiology). The paper was about what is the best diagnostic imaging modality for renal colic.

Renal Colic on the SGEM:

  • SGEM#4: Getting Unstoned

    Kidney Stones

  • SGEM#32: Stone Me
  • SGEM#71: Like a Rolling Stone
  • SGEM#97: Hippy Hippy Shake – Ultrasound Vs. CT Scan for Diagnosing Renal Colic
  • SGEM#154: Here I Go Again, Kidney Stone
  • SGEM#202: Lidocaine for Renal Colic?
  • SGEM#220: Acupuncture Morphine for Renal Colic
  • SGEM#230: Tamsulosin – You’ve Lost that Loving Feeling – For Renal Colic

Dr. Kevan Sternberg

There are greater than two million annual emergency department (ED) visits for suspected renal colic in the United States, and computed tomography (CT) scanning is now performed for more than 90% of patients who receive a diagnosis of kidney stone.

Despite a significant increase in CT use for diagnosis during the last two decades, patient-centered outcomes such as admission and intervention do not appear to have been affected.

There was a trial published in 2014 comparing radiology department ultrasound, POCUS and CT for suspected nephrolithiasis (Smith-Bindman et al. NEJM 2014). We covered this on SGEM#97 with Dr. Tony Seupaul and Dr. Spencer Wright. The bottom line from that episode was bedside emergency department ultrasound is safe and has several advantages over CT for the diagnosis of kidney stones.

Despite this evidence, recent data suggest that ultrasonography is used for less than 7% of patients receiving a diagnosis of kidney stone, and CT use has continued to increase. Similarly, although reduced-radiation-dose CT is recommended for the evaluation of renal colic, it is used for less than 10% of patients with kidney stone.

What did you do in this study?

We sought out a nine-member panel with representation from three specialty societies: ACEP, the American College of Radiology, and the American Urological Association.

How did you decide who was on the panel?

All panel members were board-certified practicing academic physicians and were nominated according to previous work on specialty- specific guidelines.

Clinical Question: For patients presenting to the ED with pain suspected to be uncomplicated renal colic, what imaging should be pursued compared with standard noncontrast CT scanning to optimize patient-centered outcomes?

To answer the question, you did a systematic review of the literature using the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-analyses) guidelines.

After reviewing and summarizing the literature for imaging modalities, we delineated specific clinical scenarios to illustrate decision making with respect to initial imaging. We came up with a total of 29 clinical vignettes representing a balance of possible permutations (age, sex, pregnancy status, likelihood of stone disease, and likelihood of acute alternative diagnosis).

How did you come up with consensus on the best diagnostic imaging strategy?

Consensus was sought with a modified Delphi process that included three rounds of anonymous voting, with two group discussions between rounds. All nine members of the group answered the vignettes in a blinded fashion.

What were the three imaging options?

For purposes of defining consensus, imaging modalities were separated into three groups (no further imaging, ultrasonography, and CT), although subtypes within imaging modalities are reported.

What were the results?

We reached at least moderate consensus in all 29 scenarios, with perfect or excellent consensus in 80%.

Five Major Themes

  1. Younger Patients (~35 years old): Even without a history of stones, CT may be avoided as long as pain is controlled (perfect consensus).
  2. Middle-Aged Patients (~55 years old): We recommend CT if there is no history of kidney stones.
  3. Older Patients (~75 years old): We recommend CT regardless of history.
  4. Pregnant and Pediatric Patients: With a typical presentation they should undergo ultrasonography and do not require initial CT if symptoms are relieved.
  5. Radiation Dose: We recommend reduced-radiation-dose CT whenever CT is used for suspected renal colic.

Were there any limitations you identified?

There are many more 29 clinical scenarios. We chose this number because it seemed to be the best balance of major factors with the least number of scenarios. The scenarios are also skewed toward those in which the clinical likelihood of a kidney stone is high according to objective criteria. Although we did include scenarios with stone being less likely and found that in these scenarios practitioners were more likely to request CT, there may have been a bias toward assuming these scenarios represented kidney stone and no other diagnosis.

Happy New Years to all the SGEMers. We will be back in 2020 with more critical appraisals of recent publications.

Trying to cut the knowledge translation window down from over ten years to less than one year using the power of social media (FOAMed).

Our ultimate goal is for patients to get the best care, based on the best evidence.

Remember to be skeptical of anything you learn, even if you heard it on the Skeptics’ Guide to Emergency Medicine.