SGEM#97: Hippy Hippy Shake – Ultrasound Vs. CT Scan for Diagnosing Renal Colic

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Date: November 24th, 2014

Guest Skeptics: Dr. Tony Seupaul and Dr. Spencer Wright. Tony is the Chairman of the Department of Emergency Medicine, University of Arkansas.

Spencer is a PGY-3 Resident in the Emergency Medicine program at the University of Arkansas.

Five Points about American Thanksgiving:

Lots of Travel
Lots of Football
Lots of Food
Lots of Shopping
Lots of Family

Case: A 36-year-old previously healthy white male is attending his families thanksgiving supper. He develops waves of right flank pain associated with vomiting. One of the relatives suggests it might be food poisoning. This does not go over well with the matriarch of the family. A second relative suggest he has probably been drinking too much which leads to another argument among some of the family members. Another relative who is a nurse suggests it could be renal colic and suggests he goes to the emergency department for assessment.

He arrives at the emergency department doing the hippy hippy renal colic shake. He describes the pain as sharp/stabbing and that has progressively become worse since onset. He says that over the last couple of hours he has felt that it is radiating down towards his groin. The pain has been associated with nausea and vomiting. He denies seeing any blood in his urine and has not experienced any pain with urination. There has been no diarrhea. H”e denies having a fever or a history of renal colic. The ibuprofen he took last night provided some temporary pain relief.

Background: We have covered renal colic a number of times on the Skeptics’ Guide to Emergency Medicine.. This included a randomized clinical trial done in France looking at the use of tansulosin for the expulsion of distal ureteral stones. (SGEM#4: Getting Unstoned). This small study of only 129 patients did not show superiority of tansulosin over placebo.

Dr. Anthony Seupaul

SGEM#32: Stone Me was a Cochrane Systematic Review looking at fluids and diuretics for rental colic. It was done by me evidence based medicine mentor Dr. Andrew Worster. The genius that started BEEM and taught me the EBM answer could always be…“it all depends”. His SR had only two small studies which met inclusion criteria. The conclusion was no reliable evidence was available to support the use of fluids or diuretics to treat renal colic.

The last time we reviewed renal colic was another Cochrane Systematic Review from Zue et al. The Bottom Line was tamsulosin was useless in most emergency department patients with ureteral colic unless their stone size exceeds at least 4mm. (SGEM#71: Like a Rolling Kidney Stone).

This time we are not going to be talking about renal colic treatment but rather diagnostic strategies.

Clinical Question: In ED patients with suspected renal colic, is ultrasound as effective as CT as a diagnostic tool?

Reference: Smith-Bindman et al.Ultrasonography versus Computed Tomography for Suspected Nephrolithiasis. NEJM 2014

Population: 2,759 patients 18-76 years of age in emergency department setting from 15 geographically diverse academic emergency departments.
 Intervention: Ultrasonography
Comparison: Computed Tomography
Outcome:
- Primary Outcome(s): 30-day incidence of high-risk diagnosis with complications related to missed or delayed diagnosis and 6-month cumulative radiation exposure.
- Secondary Outcomes: Serious adverse events, related serious adverse events, pain, return ED visits, hospitalizations, and diagnostic accuracy.

Authors’ Conclusions: “Initial ultrasonography was associated with lower cumulative radiation exposure than initial computed tomography without significant differences in high-risk diagnosis with complications, serious adverse events, pain scores, return ED visits, or hospitalizations.”

Quality Checklist for Randomized Clinical Trials:

The study population included or focused on those in the ED. YES
The patients were adequately randomized. YES
The randomization process was concealed. YES
The patients were analyzed in the groups to which they were randomized. YES
The study patients were recruited consecutively. NO
The patients in both groups were similar with respect to prognostic factors. YES
All participants were unaware of group allocation. YES
All groups were treated equally except for the intervention. UNSURE
Follow-up was complete. YES
All patient-important outcomes were considered. YES
The treatment effect was large enough and precise enough to be clinically significant. YES

Key Results:

No difference in high-risk diagnosis with complications, about 0.3%

Primary Outcomes:
- High-Risk Diagnosis: No difference (about 0.3%)
- Radiation exposure (mSv): Difference (more with CT)
Secondary Outcomes:
- Serious adverse events: No Difference about 11%
- Emergency Department Length of Stay (hr): Difference in LOS with the longest time having radiology do a US
- Return ED visits: No Difference at 1 week, 1 month or 6 months
- Hospital admission after Ed discharge: No Difference at 1 week, 1 month or 6 months
- Accuracy for diagnosis of nephrolithiasis: No Difference
  - Sensitivity ~85%
  - Specificity ~50%

The trial was a well done RCT with a high level of validity. It is unlikely that this trial will be repeated and supports what many EM physicians suspected in the diagnosis of kidney stones in an ED population.

The study did not comment on whether groups were treated differently with regards to disposition, treatment, and follow-up, based on results from different imagine modalities. It should be noted that there were exclusions for obesity in both men and women which could significantly effect the test characteristics of US patients.

This study provides strong enough evidence that there is no harm to implementing ultrasonography for suspected nephrolithiasis, and is benefit in reducing radiation exposure. This evidence should and will impact clinical care, as physicians should stay away from CT in favor of US to reduce radiation exposure, without added risk by performing US.

Comment on Authors’ Conclusion Compared to SGEM Conclusion: Author’s conclusions are similar to our conclusion, in that ultrasonography for suspected nephrolithiasis reduces cumulative radiation exposure without significant differences in bad outcomes as compared to computed tomography.

SGEM Bottom Line: Bedside emergency department ultrasound is safe and has several advantages over CT for the diagnosis of kidney stones.

Case Resolution: The 36-year-old man who presented looking like renal colic gets an ultrasound. This confirms a 4mm stone in the distal ureter. His pain and vomiting has settled in the department with intravenous ketorolac and ondansetron.

You write him prescription for an analgesia and antiemetics. You also arrange a follow up with a urologist and provide him with strict return precautions. He thanks you and you leave the room.

Dr. Spencer Wright

Clinically Application: Emergency medicine physicians should consider ultrasound for suspected nephrolithiasis when appropriate. We could be doing a favor for our patients in reducing radiation exposure, and are not putting the patient at increased risk or harm.

What Do I Tell My Patient? I would tell my patients that it looks like you have a kidney stone because you are doing the hippy hippy shake. We should start with ultrasound to lessen your exposure to radiation. Radiation increases the chance of developing cancer later in life. If further concerns arise, we can always get a CT scan. The ultrasound is just as good at diagnosing kidney stones and we may be able to get you out of the emergency department faster.

Keener Kontest Last weeks winner was Dylan Morris an EM resident from Portland Oregon. This is his second win and will receive the Double Strength cool skeptical prize.

Dylan knew that the household device was commonly used in cardiac arrest to provide oxygenation and ventilation in the 1500’s was a bellows. The device could be applied orally or rectally. When applied rectally, smoke from the fireplace was used. Rob Orman, this is where the saying…blowing smoke up your ass came from.

Listen to the SGEM this week for the Keener Question. If you know the answer than send me an email to TheSGEM@gmail.com with “keener” in the subject line. The first person to correctly answer the question will receive a cool skeptical prize.

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