IS Case 401: Rectovaginal fistula
Imaging Sciences URMC 2010
Publication Date: 2010-08-27
Patient is a 75-year-old female with a recent history of acute myocardial infarction, as well as diabetes, hypertension and chronic kidney disease now complains of loose stools coming out of her vagina.
MRI of the pelvis initially obtained to evaluate the patient's sacral decubitus ulcers demonstrates a defect in the right anterior rectal wall extending to the vagina (yellow arrowheads, Figs. 1 & 2). There is no abscess visualized. Subsequent single contrast gastrografin enema confirms the fistulous connection (yellow arrowhead, Fig. 3) between the rectum and vagina.
Gastrointestinal (GI) fistulas are communicating tracts between the gastrointestinal system and any other internal epithelial lined space, including the GI tract itself, or external surface such as the skin. This may lead to passage of the GI contents (i.e., feces) through the tract and into the involved space.
GI fistulas can be congenital or acquired in nature. Acquired etiologies are diverse and include inflammatory causes (Crohn’s disease, diverticulitis, infection), iatrogenic (post-surgical), malignancy, post-radiation therapy, foreign body or any other process that violates the bowel wall. The etiology of this patient's rectovaginal fistula is unknown.
The majority of rectovaginal fistulas are related to obstetric complications, inflammatory bowel disease, or gynecologic malignancy including associated therapies such as surgery or radiation. CT with rectal contrast may demonstrate contrast and air within the vagina. Conventional fluoroscopic GI or vaginal evaluation may confirm the extent of the fistula. Utilizing T2-weighted MRI, fluid within the fistula tract may demonstrate hyperintense signal and the fibrous wall may show hypointense signal. Dwarkasing, et al.  found the soft-tissue contrast resolution and multiplanar reconstructions of MRI to be especially useful in highlighting the fistula and the relationship to the relevant surrounding anatomy, as well as possible associated findings like edema or abscess. Body coils may limit evaluation for small fistula tracts, however a higher signal-to-noise ratio may be obtained using a phased-array coil and or endorectal coil.
- Pickhardt PJ, Bhalla S, Balfe DM. Acquired gastrointestinal fistulas: classification, etiologies, and imaging evaluation. Radiology. 2002 Jul;224(1):9-23. PMID: 12091657
- Dwarkasing S, Hussain SM, Hop WC, Krestin GP. Anovaginal fistulas: evaluation with endoanal MR imaging. Radiology. 2004 Apr;231(1):123-8. PMID: 14990820