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

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.

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

We evaluated 34 patients using the standard LARS score, and a new LARS evaluation index was established using the dynamic images of MRI defecography to verify the LARS score.

In the LARS score model, there were 10 (29.41%) mild and 24 (70.58%) severe cases of LARS. The comparison of defecation rate between the two groups was 29.36 ± 14.17% versus 46.83 ± 18.62% (P = 0.004); and MRI-rectal compliance (MRI-RC) score was 3.63 ± 1.96 versus 7.0 ± 3.21 (P = 0.001). Severe and mild LARS had significant differences using the two evaluation methods. There was a significant negative correlation between LARS and MRI-RC score (P < 0.001), and they had a negative correlation with defecation rate (P = 0.028).

MRI defecography and standard LARS score can both be used as an evaluation index to study the pathogenesis of LARS.