Imaging and Surgical Management of Anorectal Vaginal Fistulas

Abstract

Anorectal vaginal fistulas (ARVFs) can result in substantial morbidity and potentially embarrassing symptoms in adult women of all ages. Despite having what may be obvious clinical manifestations, the fistulas themselves can be difficult to identify with imaging. MRI is the modality of choice for the diagnosis and characterization of ARVFs. A dedicated protocol involving the use of vaginal gel and optimized imaging planes with respect to the vagina, as well as an understanding of the MRI pelvic floor anatomy, is crucial for reporting surgically relevant details. Ancillary findings such as postsurgical changes, inflammation, abscess, sphincter destruction, and neoplasm are well evaluated. Vaginography, contrast enema, endoscopic US, and CT can be highly useful complementary diagnostic examinations. The entities that result in ARVFs may be obstetric, inflammatory (eg, Crohn disease and diverticulitis), neoplastic, iatrogenic, and/or radiation induced. Surgical management is heavily dependent on the cause and complexity of the fistulizing disease, which are related to the location of the fistula in the vagina, the type and extent of fistula branching, the number of fistulas, sphincter tears, inflammation, and abscess. RSNA, 2018.

Rectovaginal Fistulas Secondary to Obstetrical Injury

“…25 Unilateral or bilateral puborectal atrophy, especially in the setting of potential obstetric trauma, should raise the concern for anal sphincter injury or dysfunction. 25 Computed tomography does not provide the same level of anatomic detail as MRI, it can be useful in suggesting the presence of an RVF, evaluating for undrained pelvic sepsis, and ruling out concomitant intestinal inflammation, especially diverticulitis. Fluoroscopy, via contrast enema or vaginography, can be used as a confirmatory test with sensitivities ranging from 79 to 100%.…”

Elucidating vaginal fistulas on CT and MRI

“…The strength of MRI relies on its ability to identify acute inflammatory changes and abscesses, post-surgical fibrosis and neoplastic tissue. Therefore, if allowed by the patient’s clinical conditions, MRI is the preferred imaging modality to investigate suspected urethro-, vesico-, ano- and recto-VF [2, 6].…”

“…Apart from fasting some hours before the examination, generally no special bowel preparation is required before MRI. However, some centres suggest that preliminary distension with ultrasound gel may ease identification of the vagina [6]. Ideally, the urinary bladder should be moderately distended.…”

“…Ideally, the urinary bladder should be moderately distended. Patients are scanned in the supine position, with a phased-array coil placed at the height of the pubic symphysis [6, 17, 18].…”

“…Similarly, visualisation of the abnormal communication is generally quite challenging at either ano-proctoscopy or urethro-cystoscopy. As a result, clinicians and surgeons need critical help from radiologists to (1) confirm the presence of a VF, (2) visualise its site, course and involved organs, and (3) characterise the underlying pathology [6, 7].…”