When Elevated Creatinine Is Not What It Seems: Intraperitoneal Urinary Leak Mimicking Acute Kidney Injury.

Acute kidney injury (AKI) is typically classified as prerenal, renal, or postrenal in etiology, with postrenal often referring to obstructive causes. However, certain uncommon conditions, such as intraperitoneal urinary leaks, may not fit clearly into these categories. In patients with a recent history of pelvic procedure, a complication such as intraperitoneal urinary leak can mimic AKI due to urine reabsorption across the peritoneum. When these leaks present beyond the immediate postoperative period, they can be challenging to diagnose, potentially leading to delayed management and complications.  We report the case of a male patient who presented with lower abdominal pain and dysuria four weeks after undergoing radical prostatectomy. His initial evaluation, including urinalysis and imaging, suggested a urinary tract infection (UTI), and he was discharged with antibiotics. Three days later, he returned to the emergency room with persistent symptoms, new-onset diarrhea, and elevated creatinine compared to baseline. He was diagnosed with AKI, presumed to be secondary to dehydration, and received intravenous (IV) fluids. Despite undergoing treatment, his symptoms worsened, with further deterioration in renal function in the absence of a clear cause. An abdominal MRI ultimately revealed a fluid collection behind the bladder, indicative of a urinoma. His symptoms and renal function improved significantly after the Foley catheter placement.  Intraperitoneal urinary leaks should be considered in post-pelvic surgery patients with unexplained serum creatinine elevations, as delayed recognition can lead to significant morbidity. This report underscores the importance of including intraperitoneal urinary leaks in the differential diagnosis for patients presenting with AKI following recent pelvic surgeries or procedures.