SHM Converge Scientific Abstract ePoster Gallery-Not All That Branches Is Stone: Contrast Retention Masquerading as Staghorn Calculi

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This case report describes a 67-year-old woman whose non-contrast CT abdomen/pelvis appeared to show a right-sided staghorn calculus with hydronephrosis, prompting planned percutaneous nephrolithotomy (PCNL). However, the “stone” was actually retained iodinated contrast from a CT angiogram performed 48 hours earlier. Intraoperatively, surgeons found only a small renal pelvic stone and a chronically dilated renal pelvis, but no true staghorn calculus.<br /><br />Further evaluation revealed a high-inserting ureteropelvic junction, which likely caused delayed drainage and contrast trapping in the collecting system. A nuclear renogram showed reduced right kidney function (29%). An antegrade nephrostogram confirmed ureteral patency and no filling defects, supporting the diagnosis of contrast retention rather than extensive stone disease. Because hydronephrosis persisted, a nephroureteral stent and later a nephrostomy tube were placed, and the patient improved with plans for outpatient evaluation for possible pyeloplasty.<br /><br />The report emphasizes that pseudo-staghorn calculi can closely mimic true staghorn stones on non-contrast CT, especially when imaging is performed within 48–72 hours after contrast administration and in patients with abnormal urinary anatomy or hydronephrosis. Recognizing recent contrast exposure, reviewing prior studies, and correlating imaging with clinical history and functional testing are essential to avoid misdiagnosis and unnecessary invasive procedures.

Asset Subtitle

Emma Rivas Romero

Meta Tag

Author List Aditya Rao, Emma Rivas Romero, Olga Karasik, Shiyu Jing

Category Clinical Vignettes

Concept Iodinated Contrast

Concept Staghorn Calculus

Concept Pseudo-staghorn Calculus

Concept Non-contrast Head CT

Concept Contrast Retention

Distinguished Non-Finalist

Presenter Organization UCF/HCA Greater Orlando/Osceola Internal Medicine Program

Presenting Author Emma Rivas Romero

Track Adult

Keywords

pseudo-staghorn calculus

retained iodinated contrast

non-contrast CT

staghorn calculus mimic

hydronephrosis

percutaneous nephrolithotomy

ureteropelvic junction obstruction

renal pelvic stone

nephrostogram

pyeloplasty

Iodinated Contrast

Staghorn Calculus

Pseudo-staghorn Calculus

Non-contrast Head CT

Contrast Retention