Complicated urinary tract infection and sepsis associated with suspected vesicoperitoneal fistula in a 67-year-old Chinese man

Background Urinary tract infections (UTIs) are common in older adults and may progress to sepsis, especially in the presence of structural abnormalities. Intraperitoneal urinary leakage causing urinary ascites is rare and may present with apparent acute kidney injury (AKI) and severe infection, making diagnosis and management challenging. Case presentation A 67-year-old Chinese man with prolonged indwelling catheterization was admitted to the EICU with complicated UTI and septic shock. After initial improvement, he developed abrupt anuria, rapidly increasing abdominal distension, ascites, and rising serum creatinine. Intravesical methylene blue instillation followed by paracentesis yielded pale blue ascitic fluid, and ascitic fluid creatinine exceeded the concurrent serum creatinine, establishing urinary ascites due to intraperitoneal urinary leakage. These findings suggested a suspected vesicoperitoneal fistula, possibly related to prolonged catheterization. Because the family declined cystography, cystoscopy, and surgical exploration, conservative management with continuous drainage and urinary catheter replacement was undertaken, resulting in recovery of urine output and gradual resolution of ascites. Recurrent fever later developed, and Candida tropicalis was isolated from urine and ascitic fluid; the patient improved after fluconazole therapy. Follow-up CT showed findings further supporting a suspected vesicoperitoneal fistula. Conclusions In patients with prolonged indwelling catheterization, sudden anuria​ coupled with rapid accumulation of ascites should raise a high index of suspicion​ for urinary ascites secondary to a suspected vesicoperitoneal fistula, possibly compounded by suspected concurrent catheter obstruction. Apparent AKI may represent pseudo-AKI caused by reverse intraperitoneal autodialysis. Bedside dye testing may provide rapid diagnostic support when advanced imaging is not immediately feasible. Conservative management with ascitic fluid drainage, urinary catheter replacement and optimization of catheter drainage, and tailored antimicrobial therapy may be effective when surgery is not an option.