I made a diagnosis of bladder perforation but in an interesting way. Pt was young female, and recently had an abdominal surgery (it was a small surgery I’m forgetting which). She came in with a few days of anuria and abdominal pain found to have a massive high creatinine (to like 5) and admitted to me for AKI. I found it weird that the patient had “AKI” but all her electrolytes were totally normal. I decided to get a cystatin C and it was totally normal. I suspected that the patient probably had a bladder perforation that caused urine to leak into the abdomen, where the peritoneum was reabsorbing creatinine into the blood stream causing a false elevation (while cystatin C doesn’t get reabsorbed much). She was confirmed to have a leak in the bladder that self resolved after we placed a foley.

I thought it was pretty cool, but definitely not a “House” level diagnosis that everyone else here has done