[Etiology and clinical classification of constipation]

The causes of constipation are extremely complex and are still not fully clear. In addition to secondary factors such as organic diseases and drugs, constipation may also be related to genetics, diet, intestinal flora, age, gender and so on. At present, according to the etiology, chronic constipation is divided into primary constipation and secondary constipation. However, there are significant differences among current clinical guidelines in the clinical classification of primary constipation. Some guidelines classify primary constipation as slow-transit constipation (STC), outlet obstruction constipation (OOC), and mixed constipation; however, some guidelines classify primary constipation as STC, defecation disorder (DD), mixed constipation, and normal-transit constipation (NTC); what's more, some even propose types which are different from the above sub-types. There are also differences in the understanding of the relationship between functional constipation (FC) and primary constipation and the classification of irritable bowel syndrome predominant constipation (IBS-C) among various clinical guidelines. By reviewing domestic and international guidelines and relevant literature on constipation, the following conclusions are drawn: primary constipation can be divided into IBS-C and FC, and FC can be further divided into STC, OOC, and mixed constipation; primary constipation should not be confused with FC, nor should IBS-C be classified as FC.