The Hartmann procedure, also known as a Hartmann's pouch procedure, is a type of colectomy (removal of part of the colon) where the sigmoid colon (part of the large intestine) is removed, and the remaining colon is brought out through an opening in the abdominal wall (end colostomy), with the rectal stump closed. It's often performed as an emergency surgery to address conditions like bowel obstruction, infection, or cancer.