Is portal venous outflow better than systemic venous outflow in small bowel transplantation? Experimental study in syngeneic rats

Blood drainage of the graft into the recipient portal vein reestablishes the physiological venous outflow after small bowel transplantation (SBT). However, although this approach is likely beneficial for the host, it may be technically more demanding making portocaval venous drainage the preferred arrangement during human SBT. The aim of this study was to examine in a syngeneic model of SBT the possible benefits of portoportal anastomosis (PPA) vs portocaval anastomosis (PCA) in terms of body and organ weights and bacterial translocation.

Syngeneic SBT was carried out in 25 Brown-Norway male rats weighing 249 +/- 17.5 g using either PPA (n = 13) or PCA (n = 12). Half the animals in each group were killed, respectively, on postoperative day 2 or 7. Liver, spleen, and lungs were weighed and under sterile conditions the regional lymph nodes were excised. The nodes and venous samples from the cava and portal veins were cultured for aerobes and anaerobes. Bacterial components were detected in blood by polymerase chain reaction. The findings in both groups were compared by chi2 or Mann-Whitney U tests.

Mean postoperative body weight change was -3.6% +/- 1.5% in PPA and -6.0% +/- 1.2% in PCA animals (ns) on day 2 and -6.5% +/- 2.6% and -8.0% +/- 5.0% (ns) on day 7. Liver, spleen, and lung weights were not significantly different between both groups on either end point. Gram-negative enteric bacteria were found in 3 of 7 PCA animals and 2 of 6 PPA animals at day 2 (ns) and in 1 of 6 and 4 of 6 on day 7 (ns). Aerobic gram-positive bacteria were found in 1 of 7 and 1 of 6 (ns), 3 of 6 and 3 of 6 (ns), respectively, in the 4 groups. Most positive cultures corresponded to portal blood and lymph node samples. There were no anaerobic growths.

-No body or organ weight change suggesting significant functional advantages of one technical alternative over the other could be demonstrated. -Bacterial translocation in the absence of rejection was frequent after SBT independently of the variety of venous outflow used. No difference in bacterial translocation between both anastomosis could be demonstrated. -Orthotopic venous drainage did not seem to be advantageous in the present experimental setting.