EM Decision Making: Thoughts on Mistakes in Renal Colic

Author: Peter Rosen, MD (Professor Emeritus of Clinical Medicine and Surgery at University of California, San Diego [UCSD]) // Edited by: Alex Koyfman, MD (@EMHighAK, EM Attending Physician, UT Southwestern Medical Center / Parkland Memorial Hospital) and Manpreet Singh, MD (@MPrizzleER – Clinical Instructor & Ultrasound/Med-Ed Fellow / Harbor-UCLA Medical Center)

The other day I was reading a paper on a mistake made in a diagnosis of back pain – it was thought to be renal colic, when it was renal arterial thrombosis.

I think that a common source of error in EM diagnostics comes from a desire to find a specific diagnosis that will be compatible with discharge from the ED, and a lack of reflection on what pieces of history will change the diagnostic considerations for any given patient.

We have all seen cases of ruptured aortic aneurysm that were mistakenly thought to be renal colic, probably because the ischemic pain started in the flank. It was easier to consider discharge if the back pain was called renal colic, rather than the complex task of having a vascular evaluation for the patient, if it were called an aortic aneurysm.

We are also troubled by the persistent theme that we order too many CT scans, and that we should be able to make clinical diagnoses without them. I think we do order too many imaging studies, but probably not in the geriatric population, and certainly not when we are trying to discover a surgically correctable problem.

I am a big believer in clinical judgment, and it does help to use historical reports of the disease state to enable prudent decision making. The best historical clue to the presence of renal colic is its an intermittent “crescendo” disease, where there is a period of rapid pain escalation often associated with increasing distress and functional impairment –  in other words, “colic.” When the patient does not have this intermittent aspect to the pain, look for other causes of back pain.

There are only three conditions that cause intermittent crescendo-like pain, where two of them are due to stone movement: renal colic, biliary colic, and bowel obstruction. Ischemic pain can certainly be intermittent, but does not have the crescendo component – it is better described as “restless” pain. In fact the best way to understand ischemic pain, is to inflate a blood pressure cuff above systolic pressure, and then attempt to describe the pain one is feeling in the arm distal to the cuff.

If the patient has crescendo-like pain, then one can decide on the appropriate study. In my opinion, I think with a first time episode of a kidney stone, there is enough variation in potential other causes to warrant a CT scan imaging study. If the stone appears to be a repeat episode, then you don’t really need an imaging study unless you’re concerned the stone didn’t pass (e.g. concern for hydronephrosis – do an ultrasound), or there is something else about the clinical picture that makes one worried its more than renal colic, e.g. fever that might suggest a perinephric abscess.

Syncope does not occur with renal colic, although many stone sufferers wish they were unconscious. The conditions that cause syncope are more likely not to have an intermittent quality to the associated pain.

Finally, trying to guess the location of the renal infection from its nomenclature is not helpful; calling something cystitis doesn’t mean that there is no renal involvement. A much more useful classification is simple versus complicated infection. That way one is more likely to make intelligent decisions about antibiotics, route of administration, and need for hospital admission.

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