Noncontrast multidetector-row computed tomography scanning for detection of radiolucent calculi in acute renal insufficiency caused by bilateral ureteral obstruction of ceftriaxone crystals

Noncontrast computed tomography (CT) has great advantage with higher sensitivity and more clear modalities in detecting urinary tract radiolucent calculi in patients with acute renal insufficiency (ARI) compared to other image diagnosis approaches. We report two cases (female, 28 years old; male, 39 years old) with persistent flank pain and acute anuria after the administration of ceftriaxone (4.0 g daily) for 2 days intravenously. No abnormality was found in the kidney-ureter-bladder (KUB) areas with plain abdomen X-rays. A diagnosis of bilateral hydronephrosis was made by ultrasound examination in both cases. Serum creatinine levels reached up to 257 and 810 mu mol/L (normal serum creatinine level is 40-130 mu mol/L), respectively. Vague density spots were noticed in the pelvis with noncontrast multidetector-row CT (MDCT) scanning. However, distinguishable clusters of high-density shadows were seen in pelvic areas with maximum intensity projections (MIP, CT values in 30-128 HU). Ceftriaxone crystal calculi were found on both sides of distal ureters under endoscopy. Renal function recovered in both patients after double-J ureteral stents were installed. Out results demonstrated that noncontrast MDCT scanning and MIP reconstruction as an effective diagnostic tool could provide clear images in detection of radiolucent calculi in urinary tract when conventional X-rays image are not suitable in the patients with obstructive anuria and ARI of unknown origin.