Bilateral ureterolithiasis: A true positive and false negative PoCUS exam in a patient with renal colic

Acute flank pain from suspected urolithiasis is a common presenting complaint in the Emergency Department. Multiple computed tomography (CT) has traditionally been the standard imaging modality used to diagnose obstructive kidney stones, however point of care ultrasound (PoCUS) can play an important role in the diagnostic algorithm and risk stratification of acute flank pain. Here, we present the case of a 29-year-old female with suspected urolithiasis, who underwent PoCUS that revealed right-sided hydronephrosis and normal left kidney, bladder, and aorta. A subsequent KUB was negative. As the clinical course failed to improve with therapy, an abdominal and pelvic CT was ordered revealing a 5 mm distal obstructing ureteric calculus at the right vesico-ureteric junction and another 5 mm left mid ureteric calculus. To the best of our knowledge, this is the first case in which a patient presenting with acute right-sided flank pain demonstrated unilateral hydronephrosis on PoCUS, but had clinically significant bilateral ureteric stones on CT. Emergency physicians who employ PoCUS for evaluation of flank pain must be aware of its benefits and drawbacks and how they apply to each patient. As such, we have developed a script emergency physicians can use for shared decision-making with renal colic patients when deciding on the appropriate imaging modality.