Quantitative evaluation of experimental ischemic colitis correlated with the degree of artificial bowel obstruction in rats.

Experimental ischemic colitis proximal to artificial bowel obstruction was produced under poor regional circulatory conditions in rats. Only the vessels of the left hemi-colon were ligated to obtain poor circulation (ischemia). Two types of aluminum rings were used to obstruct the bowel at the most distal portion of the ischemic colon. One, with a 4 mm internal diameter, was used for the model of partial colon obstruction with ischemia (partial obstruction, n = 25) and the other, with a 2 mm internal diameter, was used for complete colon obstruction with ischemia (complete obstruction, n = 25). The circumference of the dilated bowel was larger in complete obstruction than in partial obstruction. Ischemic colitis developed in 9 of 25 rats (34.0%) with partial obstruction and 16 of 25 (64.0%) with complete obstruction. In terms of morphometry, over half of the ischemic lesions in complete obstruction were more than 1.0 cm2, but such a large size in partial obstruction was not observed. It was demonstrated that the depth of ischemic lesions gradually increased in extensive lesions. In conclusion, complete colon obstruction with ischemia frequently caused severer ischemic colitis, together with marked distention of the proximal bowel, than partial colon obstruction with ischemia.