This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Gynaecology & Obstetrics
[{'content': 'A 52 year old lady with a vesicovaginal fistula after abdominal hysterectomy is not responding to conservative management. Most useful and impoant next investigation is: \nSelect and explain. \nA. Triple Swab Test, B. Urine culture, C. Cystoscopy, D. IVP', 'role': 'user'}, {'content': 'Answer: C \nExplanation: The most valuable investigation in an established case of a vesicovaginal fistula should be cystoscopy. Ref: Female Pelvic Health and Reconstructive Surgery By Carlin and Leong, 1st Edition; Minute Obstetrics and Gynecology consult, 2008, Page 210; Urogynecology and Female Pelvic Reconstructive Surgery : Just the Facts By Sam Siddighi, Jeffrey S. Hardesty, Page 190.', 'role': 'assistant'}]