Abstract:ObjectiveTo compare the value of three-dimensional(3D)-anorectal ultrasound and X-ray defecography in diagnosing rectocele(RC). Methods Forty-two female patients with outlet obstruction constipation(OOC) treated from December 2016 to June 2017 were examined respectively by 3D-anorectal ultrasound and X-ray defecography to compare the diagnostic results of RC,including the status and degree of RC and the incidence of complications. Results There were 35 positive cases and 7 negative cases by 3D- anorectal ultrasound and 32 positive and 10 negative cases by X-ray defecography.There were no significant differences between two groups (all P>0.05).Total 28 patients with RC were confirmed by both 3D-anorectal ultrasonography and X-ray defecography.There were significant differences in mild-,moderate- and severe-degree of RC between two inspection methods (P<0.05).There were no significant differences in the diagnostic rates of rectal intussusception,perineal hernia and puborectal muscle hypertrophy between two methods (all P>0.05).The diagnostic rate of rectovaginal septum rupture by 3D- anorectal ultrasonography was statistically higher than that by X-ray defecography (P<0.05). Conclusion There is no obvious difference in RC diagnosis between 3D-anorectal ultrasound and X-ray defecography.3D- anorectal ultrasound has more advantages in rapid,reliable,easy to operate,low cost and without obvious pain in diagnosis of RC,and its image can be observed in multiple directions.It has important diagnostic value for RC.