Confirmation of an internal hydatid bladder fistula using postoperative methylene blue retrograde injection via urinary catheter: a case report.

Abdominal hydatidosis resulting in an internal hydatid bladder fistula postoperatively is quite rare and might have serious consequences without timely treatment. A 74-year-old Tibetan woman presented with abdominal distension and was diagnosed with hydatid disease. Cyst contents were removed, and the pericyst was partially resected without contraindication. Furthermore, no internal urinary fistula was found before or during the operation, and the presence of an internal fistula was indicated by methylene blue retrograde injection via urinary catheter after the operation. The use of postoperative methylene blue retrograde injection via urinary catheter is recommended to identify internal hydatid bladder fistula formation.