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
A 52 year old lady presents with constant leakage of urine and dysuria two weeks after a complicated total abdominal hysterectomy. A diagnosis of Vesicovaginal fistula is suspected. The most impoant test for the diagnosis is: 
Select and explain. 
A. Triple Swab Test, B. Urine culture, C. Cystoscopy, D. IVP
A: Triple Swab Test
Answer: A: Triple Swab Test 
Explanation: Triple swab test is the investigation of choice to establish the diagnosis of a suspected vesico vaginal fistula. It confirms the presence of vesico vaginal fistula, and also differentiate it from uretero vaginal and urethro vaginal fistula. Ref: William's Gynecology, 1st Edition, Page 574; Textbook of Gynecology By DC Dutta, 4th Edition, Page 386, 7.