Usage patterns
大便をするto defecate; to have a bowel movement
The baby had a bowel movement, so I changed the diaper.
大便が出るfor feces to come out; to have a bowel movement
Since taking the medicine, I've been having regular bowel movements.
大便を漏らすto accidentally pass feces; to soil oneself
The dog got so nervous that it accidentally soiled itself.
大便を検査するto examine a stool sample
I had my stool checked as part of the health checkup.