Objective:Discuss the etiology of constipation;evaluate the accuracy and clinical significance of iconography in diagnosis of constipation based on colonic transit test and defecography.Methods:183 patients who had been diagnosed with constipation underwent colonic transit test.Patients who were considered outlet obstruction were further examined by defecography.Diagnosis was made according to the measurement standard established by Professor Gong Shuigen

and retrospective analysis was performed.Results:A total of 169 patients showed abnormal colonic transit.36 had actual slow-transit constipation;49 had pseudo-slow-transit constipation;and 127 had out-let obstructive constipation

among those 43 were accompanied with slow-transit constipation.Conclusion:Colonic transit test combined with defecography is the optimal

simple and noninvasive diagnostic method for constipation.The static and dynamic observation of colonic transit motility and the imaging manifestation of physiolog-ical process of defecation

especially the combination of both

enable us to further elucidate the etiology of constipation caused by slow colonic transit and functional outlet obstruction

and facilitate clinicians to design the most effective treatment.This method is significantly more advanced than the conventional barium enema technique and fiberocolonoscopy and has become the irreplaceable diagnostic method for constipation.