Renal Colic- Diagnosis
- Nephrolithiasis accounts for a significant proportion of emergency department visits every year.
- The severity of symptoms, as well as the degree of intervention required is variable.
- Controversy remains regarding the optimal diagnostic imaging modality for the diagnosis of nephrolithiasis in the ED.
- Common presenting symptoms include flank pain, nausea/vomiting, dysuria, urinary urgency and/or frequency, and hematuria.
- Absence of hematuria does not rule out nephrolithiasis.
- Up to 35% of patients will NOT have hematuria by day 3 of symptoms.
- Potential complications include:
- Complicated UTI or pyelonephritis.
- Acute urinary obstruction, potential for renal damage.
- Very broad differential diagnosis to consider.
- Nephrolithiasis is a clinical diagnosis.
- Workup may include:
- CBC, electrolytes and renal function.
- Renal function is rarely significantly impacted and therefore electrolytes/creatinine are often of little value
- STONE tool has been validated and places patient into low, medium or high probability group.
- Stone Tool (MD Calc).
- Can be used in conjunction with clinical picture to decide whether to image and/or what modality to use.
- Imaging not required in every case.
- Controversy remains between non-contrast CT and ultrasonography as first choice modality.
- Abdominal x-ray, IV pyelogram and MRI are not recommended.
- Non-contrast CT remains gold standard – low dose protocols may be used.
- Low dose CT has sensitivity of up to 99% and specificity of 94%.
- Provides information regarding stone size and location, potential complications and ability to make alternate diagnoses.
- Cons include increased health care costs and radiation exposure.
- Stones may be directly visualized as hyperechoic lines with distal shadowing.
- “Twinkling” sign when color doppler is used.
- Indirectly detects nephrolithiasis based on findings of hydronephrosis or lack of ureteral jetting.
- Sensitivity and specificity vary with practitioner skill and patient body habitus.
- Pooled literature review found sensitivity of 45% and specificity of 94%.
- 2014 study found that using U/S (either done by the emergency physician or through the radiology department) as first choice modality, did not lead to an increased risk of serious adverse events and avoided radiation exposure in large subset of patients.
Recommendation of Imaging Modality:
- In younger (< 35), healthy patients with high clinical suspicion of nephrolithiasis, imaging is not always required and CT can often be avoided.
- U/S is a good first choice modality and should be used to guide clinical suspicion and need for further imaging.
- U/S is imaging modality of choice in pregnant and pediatric populations.
- Low dose CT is generally recommended in elderly patients and in those whom the clinical suspicion is lower, or alternative diagnoses are equally as likely.
Quality Of Evidence?
We are highly confident that the true effect lies close to that of the estimate of the effect. There is a wide range of studies included in the analyses with no major limitations, there is little variation between studies, and the summary estimate has a narrow confidence interval.
We consider that the true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different. There are only a few studies and some have limitations but not major flaws, there are some variations between studies, or the confidence interval of the summary estimate is wide.
When the true effect may be substantially different from the estimate of the effect. The studies have major flaws, there is important variations between studies, of the confidence interval of the summary estimate is very wide.
- CT as gold standard is supported by high quality studies, as well as ACR and AUA guidelines.
- Using ultrasound as initial modality is certain patient populations is supported by single high quality study in 2014, as well as a recent systematic review and multispeciality consensus article.
Moore CL, Bomann S, Daniels B, et al. Derivation and validation of a clinical prediction rule for uncomplicated ureteral stone-the STONE score: Retrospective and prospective observational cohort studies. BMJ. 2014;348(March):1-12
The purpose of this document is to provide health care professionals with key facts and recommendations for the diagnosis and treatment of patients in the emergency department. This summary was produced by the BC Emergency Medicine Network and uses the best available knowledge at the time of publication. However, healthcare professionals should continue to use their own judgment and take into consideration context, resources and other relevant factors. The BC Emergency Medicine Network is not liable for any damages, claims, liabilities, costs or obligations arising from the use of this document including loss or damages arising from any claims made by a third party. The BC Emergency Medicine Network also assumes no responsibility or liability for changes made to this document without its consent.
Last Updated Nov 12, 2020
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