A Turn for the Better – The Benefit of Doing A Limited Prone Rescan to Confirm the Exact Location of an Equivocal Vesicoureteric Junction Calculus Detected on Supine Abdominopelvic CT Scan

Background: In this case report, a calculus was seen at the vesicoureteric junction (VUJ) on computed tomography (CT), in an equivocal location. The subsequent urological management is based on the precise location of the calculus (ureteric orifice at the VUJ versus urinary bladder lumen). A simple manoeuvre of doing a limited prone CT rescan of the urinary bladder confirmed the location of the calculus within the urinary bladder, thus allowing conservative management. Case Presentation: A middle-aged male with known urolithiasis presented with right sided abdominal pain, nausea and vomiting. Differentials included a right ureteric calculus and appendicitis. A CT scan of the abdomen and pelvis in the supine position revealed a 0.4 cm calculus at the right VUJ with mild right hydronephrosis. It was not certain whether this calculus was impacted at the VUJ or within the bladder lumen. A limited prone CT re-scan of the pelvis was performed, which confirmed that the calculus was within the urinary bladder, as it migrated to a dependent position in the lumen of the bladder when in the prone position. Patient was managed conservatively and passed the calculus via the urethra the next day. Conclusion: Prone CT is the gold standard for the evaluation of stone disease and can differentiate a vesical calculus from a vesicoureteric junction calculus. In cases where a supine abdominopelvic CT is performed (e.g. in institutions which do not routinely scan in prone position or in cases where a supine scan is done to exclude other pathologies), an additional limited prone CT is needed in equivocal cases for a suspected VUJ calculus. This additional limited prone CT can prevent unnecessary urologic intervention.