Barostat examination of proximal site of the anastomosis in patients with rectal cancer after low anterior resection

Patients who have undergone low anterior resection (LAR) of the rectum for cancer show symptoms of urgency and frequency of defecation after meals. Th e cause of these symptoms is unclear. It was hypothesized that the function al disorder of the proximal site of the anastomosis after low anterior rese ction of the rectum often leads to the symptoms and that the 5-HT3 receptor antagonist reduces postprandial colonic contractions. The aim of this stud y was to assess colon contractions of the proximal site of the anastomosis and the effects of the 5-HT3 receptor antagonist on the contractions. We ev aluated 37 patients who had undergone LARs, 17 with high stool frequency (m ore than our times per day) and 20 with normal stool frequency. In the firs t part of the study, basal tone, compliance of the proximal site of the ana stomosis, and response to a meal (300 kcal) were recorded with a barostat i n all patients. In the second part of the study the effects of the 5-HT3 re ceptor antagonist on contractions of the proximal site of the anastomosis a fter ingesting a meal was evaluated. Seven healthy controls were also studi ed for descending colonic tone with a barostat after a meal. Basal barostat balloon volumes showed only small variations in the two post-LAR groups. C ompliance of the proximal site of the anastomosis was similar in the two gr oups. Meal ingestion stimulated contractions of the proximal site of the an astomosis. In patients with high stool frequency the proximal site of the a nastomosis contracted earlier than in those with normal stool frequency aft er a meal. The descending colonic tone of healthy controls did not change a fter a meal. The 5-HT3 receptor antagonist inhibited postprandial contracti ons of the proximal site of the anastomosis after LAR. These observations l end support to the idea that gastrocolonic reflex increases in patients who have undergone LAR, leading to high stool frequency. Furthermore, the 5-HT 3 receptor antagonist may alleviate the symptoms of urgency and the frequen cy of defecation.