Balloon Expulsion Test for Dyssynergic Defecation

The balloon expulsion test is a simple test used to identify problems with defecation. The test involves the insertion of a balloon into your rectum, which you are then asked to evacuate. The balloon is used as a way to simulate the process of you evacuating stool during a bowel movement. The time that it takes you to dispel the balloon provides important diagnostic information to your healthcare provider.

The balloon expulsion test along with anorectal manometry is considered the primary diagnostic tests for identifying a health condition known as dyssynergic defecation, a major cause of chronic constipation. The balloon expulsion test and anorectal manometry may be performed at the same time.

three balloons
Peter Chadwick / Getty Images 

What to Expect During the Procedure

Unlike a colonoscopy, you will not be required to prepare for a complete colon cleansing. You will most likely be asked to give yourself an enema before the procedure. This is not for test accuracy, but to make you more comfortable during the procedure as you will not have to worry about passing stool along with the balloon.

Depending on where you take the test, you will either be lying on a table or sitting up. A lubricated catheter with a balloon on the end will be gently inserted into your rectum. The balloon will be filled with either water (or in some cases, air). This inflation will trigger an impulse to move your bowels and expel the balloon. You will be directed to a private bathroom in order to pass the balloon. The time it takes for you to pass the balloon will be recorded.

Diagnosis of Dyssynergic Defecation

With the balloon expulsion test, a normal expulsion time is considered to be within one minute. Longer expulsion times would be indicative of problematic defecation. The American College of Gastroenterology requires that in addition to the patient report of chronic constipation, that abnormal findings would be evidenced by at least two of the following tests for a definitive diagnosis of dyssynergic defecation:

  • Anorectal manometry
  • Anal sphincter EMG
  • Balloon expulsion test
  • Defecography

Limitations of the Balloon Expulsion Test

The balloon expulsion test only gives pass-or-fail information regarding the presence of a defecation problem. However, you could "pass" the test and still have dyssynergic defecation. Also, the balloon expulsion test is not able to identify any structural problems within your anal or rectal area. Nor does it provide your practitioner with information as to the actual dysfunction that is causing the problem. It is performed because it is a simple test that provides valuable information, but more information will be needed for your healthcare provider to make a confirmed diagnosis and offer you a viable treatment plan.

3 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. University of Iowa Hospitals & Clinics. Dyssynergic defecation.

  2. Lee BE, Kim GH. How to perform and interpret balloon expulsion test. J Neurogastroenterol Motil. 20(3):407-9. doi:10.5056/jnm14068

  3. Wald A, Bharucha AE, Cosman BC, Whitehead WE. ACG clinical guideline: management of benign anorectal disorders. Am J Gastroenterol. 109(8):1141-57. doi: 10.1038/ajg.2014.190

Additional Reading

By Barbara Bolen, PhD
Barbara Bolen, PhD, is a licensed clinical psychologist and health coach. She has written multiple books focused on living with irritable bowel syndrome.