Quiz Question: What is your diagnosis?
Computed tomography showed a classic balloon-like shape (“balloon on a string” sign1) in grade IV hydronephrosis with gross dilatation of the renal pelvis and calyces. The indistinguishable corticomedullary differentiation, membrane-like residual cortex (parenchymal rim), indicates renal atrophy2. In the present case, the very small caliber of the left ureter suggested ureteropelvic junction stricture. The diagnosis was urosepsis secondary to obstructive hydronephrosis. Hydronephrosis is one of the leading causes of severe urinary tract infection and renal dysfunction which should beware of ongoing sepsis. Escherichia coli  was isolated from both urine culture and blood culture. After emergent percutaneous nephrostomy and antibiotic treatment by cefmetazole, he was discharged two weeks later with recovered renal function.