EARLY AND LONG-TERM EFFECTS OF COLECTOMY AND ENDORECTAL PULLTHROUGH ON BILE-ACID PROFILE

Objective Although total colectomy with mucosal proctectomy and endore ctal pullthrough affects two sites critical to the enterohepatic circu lation of bile acids, little information is available regarding the ma nner in which normal digestive physiology is altered by these procedur es. This study defines the early and long-term effects of colectomy an d endorectal pullthrough on bile acid profile and the long-term effect s on biliary lipid metabolism. Summary Background Data Specific change s in bile acid absorption have been reported in patients after ileal r esection. Recent studies from our laboratory indicate that in the earl y postoperative period, colectomy with endorectal pullthrough causes a significant decrease in gallbladder bile concentrations of total bile acids, cholesterol, phospholipids, and calcium. The observation by se veral authors that the pouch undergoes morphologic and perhaps functio nal adaptation suggest that these changes may be transient and perhaps reversible. Methods These studies were done in an awake, unanesthetiz ed canine model that allows periodic sampling of gallbladder bile with out creation of an external biliary fistula and its associated sequela e. Animals were ultimately randomly assigned to either laparotomy and gallbladder cannulation (N = 6), or gallbladder cannulation with total colectomy and ileorectal anastomosis (N = 7), or biliary cannulation, colectomy, mucosal proctectomy and endorectal pullthrough with ileal reservoir (N = 5). Results Six weeks after operation, colectomy and il eorectal anastomosis were associated with a significant alteration in the relative composition of bile acids in gallbladder bile. These earl y changes were manifested by a significant (p < 0.05) increase in taur ocholic acid and a concomitant decrease in taurodeoxycholic acid. Thes e changes became even more pronounced in the ileorectal anastomosis gr oup 12 weeks after colectomy and ileorectostomy. Although similar chan ges in the relative concentrations of individual bile acids occurred i n the 6-week endorectal animals, bile acid profile was restored to nor mal by 12 weeks. Conclusions Colectomy with ileorectal anastomosis lea ds to early and significant changes in bile acid profile, which persis t and become even more pronounced with time. In contrast, the construc tion of an ileal reservoir after colectomy facilitates restoration of a normal bile acid profile. We propose that these alterations in bile acid metabolism result from adaptation of the ileal reservoir as its m ucosa assumes functional characteristics of normal colon.