Non-mechanical block. 'primary' means cause unknown. Intestinal = small intestine (about 20 feet long) or large intestine (about 6 feet long) leading to rectum. 'pseudo-obstruction' means a blockage thatis not mechanical, such as caused by a tumor, or fibrous adhesions from prior surgery, or stool impaction. The cause is an abnormality of the nerves leading to the muscle of bowel wall (lupus, scleroderma, parknsns).