1.Common Causes: (1)Unbalanced diet, for example: not enough fiber supplements in diet; (2)Disorder of bowel movements, for example: irregular defecation, restrain for a long time; (3)Abusing of laxatives; (4)Changes in lifestyle. 2.Functional Disturbance and Organic Lesions of Colon, Rectum and Pelvic Floor: (1)Mechanical obstruction of colon: benign and malignant tumor; chronic torsion; specific and unspecific inflammation; stoma stricture; chronic invagination; endometriosis; (2)Outlet obstruction of rectum and anal canal: anal fissure; anal stenosis; rectal stricture; internal sphincter achalasia; rectocele; proctoptosis, puborectalis hypertrophy; spastic pelvic floor syndrome; sacrum and rectum isolation; pelvic floor hernia;  (3)Colonic neurological and muscular disorders: Hirschsprung's disease; idiopathic megacolon; slow-time transmit colon movement; megarectum; (4)Irritable colon syndrome. 3. Neuropathic Disorders of Other Parts: (1)Diseases of central nervous system: any diseases of brain; spinal cord injury; compression by tumor; multiple sclerosis; (2)Abnormalities of peripheral nerve. 4. Psychological Disorders: (1)Depression; (2)Psychosis; (3)Anorexia nervosa. 5. Iatrogenic Causes: (1)Medications: codeine; morphia; antidepressants; anticholinergics; chalybeate. (2)Immobilization. 6. Metabolic and Endocrine: (1)Hypothyroidism;  (2)Hyperparathyroidism; (3)Hypercalcemia; (4)Hypokalemia; (5)Pregnancy; (6)Diabetes mellitus; (7) Hypopituitarism; (8)Pheochromocytoma; (9)Primary and secondary dehydration; (10)Lead poisoning; (11)Older age and dystrophy.