What to Expect During MRI Defecography

MRI scanner
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An MRI defecography uses an MRI machine to gain information about the functioning of the muscles of you pelvic floor in order to understand why you might be experiencing problems with your bowel movements. This test allows your doctor to better understand how your rectum and other pelvic organs are working (or working dysfunctionally) as you evacuate stool.

Like all MRIs, MRI defecography uses radio waves and magnets to take pictures of the soft tissues of your internal organs.

When Is MRI Defecography Used?

The MRI defecography is a fairly rare procedure and there are not many facilities in which the procedure is performed. However, when it is available, it can provide diagnostic information about the following health conditions. Keep in mind that most of these conditions are diagnosed through a combination of tests as well as by your symptom report and medical history.

  • Descending perineal syndrome (weakness and collapsing of the pelvic muscles)
  • Enterocele (bulging of the small bowel into the vagina and the rectum)
  • Dyssynergic defecation
  • Fecal incontinence
  • Rectocele (bulging of the wall of the rectum into the vagina)

MRI Defecography Versus Defecography

Traditional defecography uses X-rays to evaluate the reason behind defecation disorders. MRI defecography is thought to provide more in-depth information as to how the various organs (including the anal sphincter, the bladder, the small intestine, the uterus, and the vagina) in the pelvis interact during a bowel movement.

In addition, the use of an MRI over X-rays protects you from radiation exposure.

In the past, the MRI defecography was limited in that you were required to lay down during the procedure, which did not provide optimal information as to what actually happens during a bowel movement. Open MRIs are now available for the procedure, thus allowing you to sit upright and for your doctor to see in real-time what happens with your body when you are defecating.

On the other hand, defecography is seen as more cost-effective, is more widely available and is relatively simple to conduct.

As a general rule of thumb, the MRI defecography may be the superior test if surgery is being considered as the possible treatment for your bathroom problems.

What to Expect During an MRI Defecography

You may be relieved to learn that unlike a colonoscopy, you will not have to undergo any bowel cleaning prep prior to the appointment. Nor will you have to fast. Like all MRIs, no metal is allowed and you will be asked about any metal objects that might be inside your body. The test is painless, although some people report some mild cramping or bloating. The test can be loud, with knocking noises as the machine is taking the images.

A gel, filled with a contrast solution, will be gently inserted into your rectum. (If you are female, a solution may also be inserted into your vagina.) If you are having an open MRI, you will be seated during the exam, otherwise you will lay flat on your back.

Something called an "imaging coil", which contains sensors, will be wrapped around your pelvis if you are sitting, or placed like a blanket on your belly or back.

During the procedure you will be given directions as to when to hold in or expel the solution. You may be asked to "bear down," or alternately to relax your pelvic area.

The procedure itself takes about 30 minutes.

Also known as:

  • Endorectal coil magnetic resonance (MR) imaging
  • MR defecography

Sources:

Hetzer, F., et. al. "MR Defecography in Patients with Fecal Incontinence: Imaging Findings and Their Effect on Surgical Management" Radiology 2006 240:449-457.

Olson, C. "Diagnostic Testing for Fecal Incontinence" Clinics in Colon and Rectal Surgery 2014 27:85–90.

Roos, J., et. al. "Experience of 4 Years with Open MR Defecography: Pictorial Review of Anorectal Anatomy and Disease" RadioGraphics 2002 22:4, 817-832.

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