This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: AIIMS 2018, Subject name: Gynaecology & Obstetrics
Most useful test in vesicovaginal fistula? 
Select and explain. 
A. Cystoscopy, B. Three swab test, C. Urine culture, D. Intravenous pyelogram
A: Cystoscopy
Answer: A: Cystoscopy 
Explanation: Best investigation for VVF : Cystoscopy Cystoscopy tells about Site of fistula Size of fistula No. of fistula Ureteric opening Tests done for diagnosis of VVF: Clinical examination for site of fistula and type of lak Three swab test: methylene blue dye test Cystoscopy Cystography VCUG: voiding cystourethrography CT, urine c/s, IVP, USG Retrograde pyelography; may be done to rule out other causes of urine incontinence