Vesicocolic fistula detected by (99m)Tc-MAG3 renogram.

A 55-year-old man presented with 60-lb weight loss in 6 months. An abdominal CT demonstrated a large mass in the pelvis arising from the sigmoid colon and invading the urinary bladder. His elevated serum creatinine (1.25 mg/dL) triggered a request for a Tc-MAG3. Tc-MAG3 renogram demonstrated communication of the urinary bladder with the descending colon but no evidence of obstruction to drainage from the kidneys to the bladder. A retrograde cystogram confirmed a vesicocolic fistula. After multiple rounds of chemotherapy, the patient died 7 months later.