fistulography

Fistulography is a radiologic imaging technique in which a contrast agent is injected into a fistulous tract to delineate its course and connections. It is used to map fistulas in various anatomical regions, most commonly anorectal and genitourinary fistulas, as well as other soft-tissue fistulas.

During the procedure, the patient is usually positioned to optimize tract visualization. A catheter or cannula is inserted into the fistulous opening (often the external or internal opening) and a water-soluble iodinated contrast is slowly injected under fluoroscopic guidance. Serial radiographs or fluoroscopic images are obtained in multiple projections as the contrast fills the tract, with care to identify the tract length, branches, cul-de-sacs, and any associated abscess cavities. The tract’s relationship to surrounding structures, such as anal sphincters in perianal fistulas, is documented.

Indications include surgical planning for fistula repair, confirming the tract’s connections, locating the internal opening, detecting secondary tracts, and guiding drainage procedures. Fistulography can help determine the complexity of a fistula and the presence of abscesses that may require concurrent treatment.

Limitations include radiation exposure and reliance on patient cooperation; incomplete filling of very small or obstructed tracts; difficulty delineating extraperitoneal or suprastructural portions; and limited soft-tissue detail compared with magnetic resonance imaging or CT fistulography. Risks include contrast reaction and infection at the injection site.

Alternatives include MR fistulography or conventional MRI with a dedicated fistula protocol, CT fistulography, or ultrasound-assisted evaluation, which may provide superior soft-tissue contrast and a more comprehensive assessment of fistula anatomy, especially for complex or deep fistulas.