for people ages 18-75 (full criteria)
study started
estimated completion:
Ralph C Wang



This is a randomized trial to determine the effect of a clinical decision support tool on image ordering for patients with suspected nephrolithiasis. Patients who present with acute unilateral flank or abdominal pain in whom emergency department providers suspect nephrolithiasis will receive either a clinical decision support module or no module.


CT scan is overused for patients who present to the ED with suspected nephrolithiasis (acute flank or abdominal pain). We have developed a clinical decision support (CDS) tool to identify those patients in whom ultrasound is appropriate. The CDS tool is based on the Study of Ultrasonography vs. Computed Tomography for Suspected Nephrolithiasis in the Emergency Department.

Our goal is to assess the effectiveness of a clinical decision support (CDS) tool to improve advanced imaging for suspected nephrolithiasis in the ED. We hypothesize those randomized to receiving CDS will order CT less often compared to those receiving control. Also, we hypothesize those randomized to receiving CDS will have a similar ED length of stay and rate of unexpected ED return as those receiving control.

Study design: Randomized trial of a CDS tool embedded in the electronic health record for patients with suspected nephrolithiasis. The study will be conducted at UCSF Department of Emergency Medicine.

Study subjects: We will enroll adult patients who present to the ED who present with "suspected nephrolithiasis", which we define as those with 1) symptoms of nephrolithiasis, and 2) require cross-sectional imaging. Symptoms of nephrolithiasis include acute unilateral flank and/or abdominal pain, typically described as severe and colicky. The pain is accompanied by nausea, vomiting, and urinary symptoms, such as hematuria. The imaging studies emergency physicians typically order for suspected nephrolithiasis include: CT scan (CT scan without contrast, CT scan with contrast, CT scan with and without contrast), radiology ultrasound, or point of care (POCUS) ultrasound. We will enroll patients whose providers order an imaging test for kidney stone - CT scan, ultrasound, or POCUS.

Sampling, recruiting and retaining subjects: We will enroll consecutive patients who present to the ED with the selection criteria. Those with suspected nephrolithiasis but have an exclusion criteria will be recorded and compared to those who were enrolled. Eligible patients will be randomized to either receiving CDS recommendations or no CDS recommendations. Subjects will not receive informed consent, and will not be contacted by staff.

Intervention: The intervention is the CDS tool, which consists of 2 components: 1) assess the presence of appropriateness criteria for ultrasound; 2) provide recommendations to encourage clinicians to order ultrasound, and a place to change the order. The CDS tool will be placed or integrated into EPIC, at the point of order entry. The tool will be triggered by an order for cross-sectional imaging to identify or rule out kidney stone. At UCSF, this will include CT for suspected nephrolithiasis.

The main outcome variable will be proportion of study arm who receive CT, and median radiation dose. Proportion of study arm who receive CT is defined as #CT scans ordered/#patients in study arm. The secondary outcomes will include proportion of patients with an unscheduled return due to missed diagnosis, cost, ED length of stay.


Nephrolithiasis Kidney Calculi Ultrasound-first Clinical Decision Support tool Clinical Decision Support


You can join if…

Open to people ages 18-75

  • Adult patients who present to the ED who present with "suspected nephrolithiasis",which we define as those with 1) symptoms of acute flank or abdominal pain, and 2) are deemed to require CT imaging.

You CAN'T join if...

  1. Adults aged <18 and > 76
  2. Obese (men < 285lbs, women < 250lbs)
  3. History of kidney disease (ESRD, hemodialysis, post kidney transplant, solitary kidney)
  4. High risk of clinically significant alternative diagnosis (appendicitis,cholecystitis, AAA, ovarian torsion)

Lead Scientist

  • Ralph C Wang
    Professor, Emergency Medicine. Authored (or co-authored) 33 research publications


not yet accepting patients
Start Date
Completion Date
University of California, San Francisco
Study Type
Last Updated