To explore the pathogenesis of anterior resection syndrome by magnetic resonance imaging rectal defecography.

Background: Over 90% of rectal cancer patients develop low anterior resection syndrome (LARS) after sphincter-preserving resection. The current globally recognized evaluation method has many drawbacks and its subjectivity is too strong, which hinders the research and treatment of LARS.

Aim: To evaluate the anorectal function after colorectal cancer surgery by quantifying the index of magnetic resonance imaging (MRI) defecography, and pathogenesis of LARS.