RESUMO
PURPOSE: The aim of this prospective study was to analyze anorectal physiologic and clinical outcomes of the colonic J-pouch-anal anastomosis compared with the traditional straight colorectal anastomosis after ultra-low anterior resection in patients with rectal cancer, thus to define if this method of modified reconstruction has a functional superiority. METHODS: After total mesorectal excision for mid or low rectal cancers, patients were randomized to either a straight (n=23) or a colonic J-pouch anastomosis (n=24) to the lowermost rectum or anal canal. Functional outcomes were compared between two groups using an anorectal manometry performed before and 1 year after surgery and a bowel function questionnaire administered 6 months and 1 year postoperatively. RESULTS: Except the arithmetic level of anastomosis which was significantly higher in straight group than in pouch group (5.1 +/- 1.2 cm vs. 3.8 +/- 0.9 cm; P=0.0001), the two groups were well matched for demographic distribution, pathologic stage, colonic segment used for neorectum and use of adjuvant therapies. Patients with colonic J-pouch anastomosis showed functional superiority in terms of frequency of bowel movements, degree of urgency at 6 months (P<0.0001 and =0.03, respectively) and 1 year postoperatively (P<0.0001 and <0.05, respectively). Functional parameters, including incontinence to liquid stool and impaired discrimination between gas and stool were more pronounced in straight group after 6 months (P=0.04, and <0.05, respectively), but the differences were not statistically significant after 1 year. Sensation of incomplete evacuation was not different statistically between groups at 6 months, but more common in J-pouch group at 1 year (39.1% vs. 8.3%; P=0.04). As well as the length of high pressure zone and presence of rectoanal inhibitory reflex, there was no difference in sphincter pressure parameters between groups either before or 1 year after surgery. Maximal tolerable volume of the neorectum in J-pouch group was 110.2 +/- 16.7 ml, which was significantly larger than that of 74.1 +/- 14.9 ml in straight group (P<0.0001), and the neorectum in J-pouch group was significantly more compliant than that in straight group (6.1 +/- 1.9 vs. 3.3 +/- 2.1; P<0.0001) in 1 year after surgery. CONCLUSIONS: Construction of a colonic J-pouch as a substitute for the rectum restores neorectal volume and compliance. Clinically it offers patients superior anorectal function compared with straight anastomosis. To minimize evacuation difficulty associated with the pouch, optimal size of the pouch should be defined, thus to achieve an ideal balance between stool frequency/urgency and evacuation problems through larger prospective studies.