Colonic transit in the empty colon after defunctioning ileostomy: do we really know what happens?

BACKGROUND: There is disagreement amongst surgeons about the use of oral mechanical bowel preparation (MBP) prior to low anterior resection with diverting ileostomy. Colonic transit in the early post-operative period is an important factor in determining the role of MBP, as propagation of any stool remaining in the defunctioned colon may exacerbate morbidity in the event of anastomotic leak. We studied colonic transit time in the first 7 days following low anterior resection with diverting ileostomy.
METHODS: We conducted a prospective observational study of patients with rectal cancer undergoing elective low anterior resection with diverting ileostomy in a tertiary colorectal unit. Twenty radio-opaque markers were inserted into the caecum via the distal limb of the loop ileostomy at surgery. Plain abdominal radiographs were taken on post-operative days 1, 3 and 5. The primary endpoint was passage of the markers to the neorectum. Data were collected on treatment, return of gastrointestinal function and complications.
RESULTS: Twenty-two patients (mean age 68.5 years; 18 males) participated in the study. In 20 patients, all markers remained in the right colon on day 7. Three markers were present in the left colon in one patient, and eight markers were present in the neorectum in another patient, on the seventh day.
CONCLUSIONS: Colonic transit may be abolished by the presence of diverting ileostomy. It should now be established whether clearance of the left colon alone, using enemas, is sufficient for patients undergoing low anterior resection, thus avoiding the morbidity associated with oral MBP.