The patient presented with abdominal pain, vomiting, and systolic blood pressure of 60 mmHg. Bloods demonstrated acute renal failure with creatinine 186 micromol/L (normal range 45 to 90), eGFR 27 (normal > 90), lactate 7.1 mmol/L (normal range 0.2 to 1.8). E. coli was subsequently detected in blood cultures, and purulent urine was visualized at the time of right nephrostomy insertion, thus confirming the diagnosis of urosepsis. 

CT abdomen/pelvis with contrast demonstrating relative hypoenhancement of the renal cortex and normal enhancement of the renal medulla, in keeping with the reverse rim sign seen in renal cortical necrosis. Renal cortical necrosis can be due to a variety of causes, including severe hemodynamic shock (sepsis, traumatic or post-partum hypovolemia), microangiopathic hemolysis, and acute renal transplant rejection. In this particular case, the cause was septic shock due to an obstructed renal calculus.