Characterising the Natural History of Mucosal Metabolism During Colorectal Anastomotic Healing

This pilot study aims to investigate anastomotic healing and its underlying mechanisms at a mucosal level. It is a first-in-human study which will demonstrate the safety of post-operative endoscopic assessment of a colorectal anastomosis and provide preliminary data in order to power future interventional studies. 100 patients undergoing elective left colonic or rectal resection with a primary anastomosis will be recruited pre-operatively throughout the study period. This study will not affect or delay the intended treatment for study participants. Patients will undergo serial endoscopic examination of the anastomosis post-operatively. Blood, urine, stool, and mucosal biopsies will be serially collected. A subgroup of 20 patients with a defunctioning ileostomy will be recruited to an interventional arm. This interventional arm will demonstrate the safety of re-introducing ileostomy effluent into the downstream (distal) limb of an ileostomy. The preliminary data will enable exploration of the association between microbiome and post-operative function and enable adequate powering of future interventional studies.