Earlier series in a smaller number of patients reported sensitivities of 100% [41,42]. Limitations of vaginography include occlusion of low fistula by the Foley catheter balloon and completely filling complex fistulous tracts that may have several branches. The high sensitivity and PPV supports the use of this procedure in certain clinical scenarios. MRI Pelvis Rectovaginal and anovaginal fistula may be visualized on MRI performed with a phased array body coil, but to our knowledge, there are no published studies reporting the accuracy of fistula detection. As such, the advantages of scanning with or without IV contrast have not been studied. Based on our knowledge of anorectal fistula, there is a clear advantage to using IV contrast to visualize collapsed tracts that do not contain fluid and would be difficult to see on T2-weighted sequences. MRI pelvis without IV contrast may be helpful in certain clinical situations but is not as good as one performed with IV contrast. Stoker et al [43] compared endoluminal coil MRI with and without IV contrast to endoluminal US, reporting a PPV for detection of fistula tracts of 92% and 100%, respectively. Radiography Pelvis Radiography is not useful in this clinical scenario because it cannot assess the presence or absence of an abscess or fistula tract. US Pelvis Transrectal Yee et al [44] reported that endoluminal US detected only 28% of rectovaginal fistula in 25 patients prior to surgical repair. However, more recent reports show improved detection; consequently, this procedure can be useful in certain clinical situations for fistula detection. In 28 patients, Yin et al [45] had a PPV of 100% for the identification of the anorectal opening of the fistula and 93% for the identification of the vaginal opening, and an overall PPV of the fistula of 90%. The limitation of endoluminal US is identification of complex fistulas with secondary branches, visualization of occluded branches, and visualization of fistula that extend beyond the field of view.
Anorectal Disease. Earlier series in a smaller number of patients reported sensitivities of 100% [41,42]. Limitations of vaginography include occlusion of low fistula by the Foley catheter balloon and completely filling complex fistulous tracts that may have several branches. The high sensitivity and PPV supports the use of this procedure in certain clinical scenarios. MRI Pelvis Rectovaginal and anovaginal fistula may be visualized on MRI performed with a phased array body coil, but to our knowledge, there are no published studies reporting the accuracy of fistula detection. As such, the advantages of scanning with or without IV contrast have not been studied. Based on our knowledge of anorectal fistula, there is a clear advantage to using IV contrast to visualize collapsed tracts that do not contain fluid and would be difficult to see on T2-weighted sequences. MRI pelvis without IV contrast may be helpful in certain clinical situations but is not as good as one performed with IV contrast. Stoker et al [43] compared endoluminal coil MRI with and without IV contrast to endoluminal US, reporting a PPV for detection of fistula tracts of 92% and 100%, respectively. Radiography Pelvis Radiography is not useful in this clinical scenario because it cannot assess the presence or absence of an abscess or fistula tract. US Pelvis Transrectal Yee et al [44] reported that endoluminal US detected only 28% of rectovaginal fistula in 25 patients prior to surgical repair. However, more recent reports show improved detection; consequently, this procedure can be useful in certain clinical situations for fistula detection. In 28 patients, Yin et al [45] had a PPV of 100% for the identification of the anorectal opening of the fistula and 93% for the identification of the vaginal opening, and an overall PPV of the fistula of 90%. The limitation of endoluminal US is identification of complex fistulas with secondary branches, visualization of occluded branches, and visualization of fistula that extend beyond the field of view.