The first diagnosis considered for this condition is outlet obstructive constipation, followed by tumor of the colorectum, and the last diagnosis considered is inflammation of the colorectum. The diagnosis of outlet obstructive constipation mainly includes prolapse of rectal mucosa, prolapse of rectum, hypertrophy of puborectal muscle, and redundant colon, etc. These four conditions can lead to anal urge for stool, but no stool can be removed. For malignant tumors of the colorectum and inflammatory diseases of the colorectum, anoscopy, anoscopy, colonoscopy or sigmoidoscopy, CT of the abdominal and pelvic cavity and tumor markers are required for a definite diagnosis.