Endoscopic and histologic correlates of intestinal ischemia in a canine model.

The purpose of this study was to correlate endoscopic, microscopic and gross changes in an isolated ischemic segment of canine jejunum. Three experiments were devised. The arterial and venous blood supply to a 20 cm segment of distal jejunum in mongrel dogs was isolated and the bowel divided. External and endoscopic photography and intestinal biopsies were obtained at 0, 5, 15, 30, 60, 120, 180 and 360 minutes after vascular occlusion. Arterial occlusion was characterized by initial blanching of the mucosa, hyperperistalsis, edema, spasm and serosal pallor within 5 minutes. Microscopically, capillaries became congested at 5 minutes; epithelial sloughing occurred in 1-2 hours; necrosis of the tips of the villi occurred at 4 hours; and necrosis of muscle fibers was observed at 18 hours. Venous occlusion was characterized by marked mucosal and edema and hemorrhages within 5 minutes. At 15 minutes serosal hemorrhages were observed. Mucosal sloughing with hemorrhage and infarction were observed at 3 hours. Microscopically, mucosal capillary congestion was severe at 5 minutes and widespread hemorrhages were seen at 15 minutes. Mucosal sloughing began at 30 minutes and was severe by 60 minutes. Complete mucosal necrosis occurred by 3 hours. Combined arterial and venous occlusion was similar to arterial occlusion alone except for the early appearance of punctate mucosal hemorrhages. Massive submucosal hemorrhages did not occur. Results demonstrate that arterial and venous occlusion can be differentiated endoscopically; venous occlusion appears to be more readily injurious; and endoscopy and biopsy are valuable in diagnosis and management.