Unlocking the colon clock: Bridging the gap in colonic transit time studies for optimal management of chronic constipation

Functional constipation affects up to 15% of the global population, significantly affecting the quality of life and imposing substantial clinical and economic burdens. Colonic transit time (CTT) studies have emerged as a pivotal diagnostic tool for distinguishing various types of functional constipation (<i>i.e.,</i> slow transit constipation, normal transit constipation, and ano-rectal dyssynergia), thereby guiding personalized treatment strategies and enabling precise monitoring of therapeutic response. CTT studies using radiopaque markers (ROM) have been the most widely used technique by researchers worldwide. Despite its affordability and high diagnostic yield, the ROM CTT study remains grossly underutilized in routine clinical practice largely due to a pervasive lack of awareness among physicians regarding its methodological nuances and clinical advantages. This narrative review systematically examined the multifaceted role of ROM CTT studies in clinical practice. It underscored how ethnic, dietary, and lifestyle factors profoundly influence colonic motility, thereby necessitating the development of population-specific diagnostic protocols. The review also highlighted the significant variability in imaging methodologies, such as differences in radiographic timing and patient positioning (supine <i>vs</i> erect), which further complicate the interpretation and reliability of CTT assessments. By drawing on a wide spectrum of research, this review advocated for enhanced physician education and the implementation of standardized, evidence-based protocols. Such initiatives are critical to optimizing the diagnostic accuracy and clinical utility of ROM CTT studies, ultimately leading to more effective management of refractory constipation and improved patient outcomes.