What causes tenesmus?

Conditions that can cause tenesmus include anorectal abscesses, colon infections and Crohn's disease, as stated by the U.S. National Library of Medicine. It can also be caused by colorectal cancers.

Tenesmus is the feeling that a person needs to pass a stool, even if they have already emptied the bowels. This feeling can lead to straining and cramping. One of the most common causes of the condition is inflammatory bowel disease, according to the University of Maryland Medical Center. A doctor can perform different tests such as a colonoscopy to determine the cause. This helps determine the proper treatment for the condition.