Fig. 1From: Development of colonic transit time and ultrasound imaging tools as objective indicators for assessing abnormal defecation associated with food intake: a narrative review based on previous scientific knowledgeDefecation mechanism. In normal defecation, the lack of an urge to defecate indicates the absence of stool in the rectum. In this case, faeces are stored on the oral side of the sigmoid colon. There are two causes of dysfunction: rectal hypoesthesia and functional stool drainage disorders. Measuring the gastrointestinal transit time is useful for evaluating these causes of dysfunctionBack to article page