Ref: l. Campbell-Walsh Urology, 9th Edition, Chapter 72, Urinary tract fistula.2. Glenn's Urological Surgery, Sixth Edition, Chapter 26 Enterovesical and Reciourethral Fishdae3. Sahiston Textbook of Surgery, 19th Edition, Pg: 1313.Explanation:"The most common presenting symptom of colovesical fistula is pneumaturia"About other optionsBarium enema is diagnostic - barium enema will fail to reveal a fistula 50% of the time.Common in females - more common in men than in women because the uterus prevents the sigmoid from adhering to the bladder.May be a surgical complication - Colovesical fistulas can occur as a result of surgical complication, however it is rare. Iatrogenic Rectovesical fistula is more common.Hence, option A. commonly presents withpneumaturia appears more appropriate.Vesicoenteric fistulasIt commonly occurs in the setting of bowel disease, such as diverticulitis. colorectal carcinoma, and Crohn's disease.Less common causes include irradiation, infection, and trauma (external penetrating trauma as well as iatrogenic surgical trauma).Diverticulitis is the most common cause of colovesical fistula, accounting for approximately 70% of cases.Sigmoid-vesicular fistulas are more common in men than in women because the uterus prevents the sigmoid from adhering to the bladder.Women with sigmoid fistulas have usually had a prior hysterectomyClinical featuresAlthough enterovesical fistulae are almost always secondary to extravesical pathology, they present with urinary symptomsThe MC presenting symptom is pneumaturia, (seen in 50% to 85% cases)Irritative voiding symptoms (in 70% to 90% cases)Fecaluria (20% to 68%) of patients with enterovesical fistulae and tends to be more common with diverticular and malignant fistulae.The classic presentation of vesicoenteric fistula is described as Gouverneur's syndrome and consists of suprapubic pain, urinary frequency, dysuria, and tenesmus.Other symptoms include hematuria, abdominal pain, diarrhea, urinary retention, perineal pain, hematochezia, and fever.Urine in the stool is rarely reported with enterovesical fistulae: these fistulae tend to be unidirectional with flow from the high-pressure intestinal tract to the low-pressure urinary tractInvestigationsThe most reliable test Computed Tomography (CT Scan), which may demonstrate air in the bladder ' .The triad of findings on CT that are suggestive of colovesical fistulaBladder wall thickening adjacent to a loop of thickened colonAir in the bladder (in the absence of previous lower urinary tract manipulation)Presence of colonic diverticula.A barium enema will fail to reveal a fistula 50% of the time, and an IV pyelogram is even less accurate.Cystoscopy usually reveals cystitis and bullous edema at the site of the fistula, but the test is helpful to exclude cancer (colon or bladder) as the cause of the fistula.ManagementNonoperative managementIn nontoxic, minimally symptomatic patients with nonmalignam causes of enterovesical fistulas, a trial of medical therapy including intravenous total parenteral nutrition bowel rest, and antibiotics may be warranted.This may be the preferred initial approach, especially in patients with Crohn's disease, in whom the notion of immediate exploratory laparotomy and bowel resection is discouraged because of the chronic relapsing nature of the disease.Operative ManagementThe goal of operative management is to separate and close the involved organs with minimal anatomic disruption and normal long-term function of both systems.Both one- and tw o-stage procedures have been advocated, depending on the clinical circumstances.A one-stage procedure involves removal of the fistula, closure of the involved organs, and primary reanastomosis of the bowel after resection of the involved bowel segment.A two-stage approach advocates removal of the fistula, closure of the involved organs, and construction of a temporary proximal diverting colostomy, with a later return to the operating room for colostomy takedown once the fistula track is demonstrated to be closed.The choice of whether to proceed with a one- stage or two-stage repair is influenced by the location and cause of the fistula, the patient's general condition, the presence of a pelvic abscess, and the presence of colonic obstruction.Patients with an inflammatory cause of the fistula hut without gross contamination can be treated with a one-stage procedure, whereas those with unprepared bowel, gross contamination, or abscess may require a two-stage procedure.