Effect of methylene blue infusion into the inferior mesenteric artery on lymph node retrieval after transabdominal total mesorectal excision for rectal cancer: a retrospective cohort study

Background: This study aimed to investigate the effect of methylene blue injection via the inferior mesenteric artery on lymph node retrieval in postoperative rectal cancer specimens. Materials and methods: This retrospective cohort study enrolled 120 patients undergoing radical rectal cancer resection by the same surgical team at a hospital in Bengbu City between July 2023 and December 2024. Among these, 60 patients operated on between April and December 2024 underwent heparinization of the surgical specimen post-extraction, followed by methylene blue arterial perfusion (experimental group). The remaining 60 patients, operated on between July 2023 and March 2024, received no special treatment after specimen removal (control group). The two groups were compared regarding total postoperative lymph node detection rates, positive lymph node detection rates, and average time per lymph node examined. Results: < 0.001]. Conclusions: Methylene blue injection via the inferior mesenteric artery enhances the total number of lymph nodes detected post-rectal cancer surgery while reducing the average time per lymph node examination. This ensures accurate pathological staging and holds promise for providing more precise evidence for post-operative prognosis assessment and treatment planning in rectal cancer.