tenesmus n : painful spasm of the anal sphincter along with an urgent desire to defecate without the significant production of feces; associated with irritable bowel syndrome
Tenesmus is a feeling of incomplete defecation. It is experienced as an inability or difficulty to empty the bowel at defecation. It is frequently painful and may be accompanied by involuntary straining and other gastrointestinal symptoms.
Vesical tenesmus is a similar condition, referring to difficult or failed attempts to urinate despite the bladder feeling full.
Rectal tenesmus is sometimes used as a retronym to further distinguish defecation-related tenesmus from vesical tenesmus.