CT provides important information in the diagnosis of the underlying etiology of the fistula, as well as detecting the course and locations of fistulae. To our knowledge, there are no data in the literature regarding the use of IV contrast in the detection of rectovaginal or rectovesicular fistula. Water-soluble contrast should be placed in the bowel or bladder to try to opacify fistulous tracts, depending upon the clinically suspected location of the tract. The bladder can be opacified retrograde (CT cystogram) or antegrade with delayed imaging after IV contrast administration. Kuhlman et al [35] reported an accuracy of 60% for the CT detection of enterovaginal or vesicovaginal fistula by the identification of contrast material in the vagina from the bowel or bladder. In a study of 37 patients with colovaginal and colovesicular fistulae, CT had a diagnostic sensitivity of 76.5% for fistula detection and 94.1% for defining the etiology of the fistula [1]. However, this study does not report how the diagnosis of fistula was made and what type of contrast material was used. Fluoroscopy Contrast Enema Fluoroscopic contrast enemas performed for the diagnosis of perforation or leak, rectovaginal or rectovesicular fistula, pouchitis, or proctitis can be performed with water-soluble contrast or barium. Though this procedure is reported to have low sensitivity and specificity as detailed in the following paragraph, it may be useful for observing subtle fistulas. In general, water-soluble contrast is preferred if a leak or perforation are suspected to avoid barium spillage into the peritoneal cavity or extraperitoneal pelvis. Using barium may also interfere with a subsequent CT scan because of the streak artifact that it causes on CT. Care should be taken not to inadvertently obscure a distal fistula with the enema or catheter tip or the balloon of a catheter. The performance of contrast enema for the detection of rectovaginal fistulas is reported in small series from older published literature.
Anorectal Disease. CT provides important information in the diagnosis of the underlying etiology of the fistula, as well as detecting the course and locations of fistulae. To our knowledge, there are no data in the literature regarding the use of IV contrast in the detection of rectovaginal or rectovesicular fistula. Water-soluble contrast should be placed in the bowel or bladder to try to opacify fistulous tracts, depending upon the clinically suspected location of the tract. The bladder can be opacified retrograde (CT cystogram) or antegrade with delayed imaging after IV contrast administration. Kuhlman et al [35] reported an accuracy of 60% for the CT detection of enterovaginal or vesicovaginal fistula by the identification of contrast material in the vagina from the bowel or bladder. In a study of 37 patients with colovaginal and colovesicular fistulae, CT had a diagnostic sensitivity of 76.5% for fistula detection and 94.1% for defining the etiology of the fistula [1]. However, this study does not report how the diagnosis of fistula was made and what type of contrast material was used. Fluoroscopy Contrast Enema Fluoroscopic contrast enemas performed for the diagnosis of perforation or leak, rectovaginal or rectovesicular fistula, pouchitis, or proctitis can be performed with water-soluble contrast or barium. Though this procedure is reported to have low sensitivity and specificity as detailed in the following paragraph, it may be useful for observing subtle fistulas. In general, water-soluble contrast is preferred if a leak or perforation are suspected to avoid barium spillage into the peritoneal cavity or extraperitoneal pelvis. Using barium may also interfere with a subsequent CT scan because of the streak artifact that it causes on CT. Care should be taken not to inadvertently obscure a distal fistula with the enema or catheter tip or the balloon of a catheter. The performance of contrast enema for the detection of rectovaginal fistulas is reported in small series from older published literature.