Tests and diagnosis
By Mayo Clinic staff
Physical examination
To figure out the cause of a rectovaginal fistula, your doctor will perform a physical examination to try to locate the fistula and check for a possible tumor mass, infection or abscess. The exam includes a visual inspection of your vagina, anus and the area between them. Your doctor will perform a digital exam, inserting a gloved and lubricated finger into your vagina while feeling the perineum with another gloved finger, and then perform a rectal exam by inserting his or her gloved finger into your anus.
Unless the fistula is very low in the vagina and readily visible, your doctor may use a speculum to visualize the inside of the vagina. This may allow him or her to see the opening of the fistula inside your vagina. An instrument similar to a speculum, called a proctoscope, may be inserted into your anus and rectum to check the health of your rectum.
Tests for identifying fistulas
Often a fistula isn't found during the physical exam. A variety of other tests may be used to locate and evaluate a rectovaginal fistula. These tests also help your medical team in planning for surgery.
- Water and blue dye tests. Filling the vagina with water and the rectum with air can help locate the fistula. Air passing from the rectum through the fistula forms bubbles on the vaginal side of the passage. Another test involves placing a tampon into your vagina, then injecting blue dye into your rectum. Blue staining on the tampon shows the presence of a fistula.
- Contrast tests. A vaginogram or a barium enema can help identify a fistula located in the upper rectum. These tests use a contrast material to show either the vagina or the bowel on an X-ray image.
- Computerized tomography (CT). A CT scan is a special X-ray technique that provides more detail than a standard X-ray does. A CT scan of your abdomen and pelvis can help locate a fistula and determine its cause.
- Magnetic resonance imaging (MRI). This test uses a magnetic field and radio waves to create images of soft tissues in your body. MRI can show the location of a fistula as well as involvement of pelvic organs or the presence of a tumor.
- Anorectal ultrasound. This procedure uses sound waves to produce a video image of your anus and rectum. Your doctor inserts a narrow, wand-like instrument into your anus and rectum. Anorectal ultrasound can evaluate the structure of your anal sphincter and may show defects caused by obstetric injury.
- Anorectal manometry. In this test, a narrow, flexible tube is inserted into your anus and rectum and a small balloon at the tip of the tube is expanded. The test measures the sensitivity and function of your rectum and can provide useful information when a fistula is due to Crohn's disease or radiation. This test does not locate fistulas but can help with planning repair.
- Other tests. If your doctor suspects you may have inflammatory bowel disease, he or she may order a colonoscopy. This test allows your doctor to view your colon using a thin, flexible, lighted tube with an attached camera. During the procedure, your doctor can take small samples of tissue (biopsy) for laboratory analysis, which can help confirm the diagnosis of Crohn's disease. If you've received radiation therapy to your pelvic region, your doctor may do more small bowel tests, including X-rays, to make sure you don't also have a small bowel fistula.
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