<prompt> Investigation of Choice for Vesico-Vaginal Fistula is:IVPCystoscopy3 Swab TestX ray  <response>: Ans. c 3 Swab TestRef: Shaws Textbook of Gynecology 16th Ed; Page No-222Vesicovaginal Fistula VVF Most common cause of bladder fistulae 80-90 in India:Obstetrical problem. Prolonged labour-- operative--vaginal caesarean section. Sometime gynaecological cause: Hysterectomy Sling operations for stress incontinence Clinical features: Continuous dribbling of urine--no micturition true incontinence. Investigation: Methylene swab test. The vaginal cavity is packed with three sterile swabs; 50-100mL of dilute methylene blue dye is injected into the bladder through the catheter. If there is a VVF present, the methylene blue dye stains the uppermost swab. IVP: Normal in Vesicovaginal Fistula VVF, but Hydronephrosis on the affected side seen in Ureteric Fistula. 