Radiotherapy-Related Bladder Fistula: A Hidden Cause of Recurrent Abdominal Symptoms

BACKGROUND Non-traumatic bladder rupture, a rare yet potentially life-threatening condition, can stem from diverse factors such as malignancies, bladder inflammation, or bladder diverticulum rupture. Pelvic radiotherapy, in extremely rare instances, can lead to radiation cystitis and subsequent bladder fistula formation. Patients with such conditions often present with abdominal pain, hematuria, oliguria, and urinary ascites. The diagnosis of radiotherapy-related bladder fistula poses significant challenges, particularly in patients with protracted illnesses and atypical abdominal symptoms, as it can be easily overlooked. CASE REPORT We present the case of a 60-year-old woman who, 14 years following a hysterectomy, bilateral adnexectomy, and radiotherapy for cervical carcinoma, developed recurrent abdominal pain and ascites. Initially, her symptoms were misattributed to gastrointestinal disorders. However, ascites analysis, which revealed markedly elevated creatinine and urea nitrogen levels in the ascitic fluid compared to serum, led to the suspicion of urinary ascites. The definitive diagnosis of an intermittent bladder fistula was confirmed through the instillation of a saline-methylene blue solution via the urinary catheter, which resulted in the drainage of blue ascitic fluid. CONCLUSIONS The diagnosis of vesical fistula is often challenging due to its diverse presentations and the possibility of being overlooked by CT. However, early recognition and appropriate management are crucial to prevent severe complications. This case highlights the importance of considering bladder fistula in the differential diagnosis of unexplained ascites and peritonitis, especially in patients with a history of pelvic radiotherapy or cystoscopic treatment.