Clinicopathological evaluation of anoxic mucosal injury in strangulation ileus

Abstract

Background: In patients with strangulation ileus, the severity of bowel ischemia is unpredictable before surgery. To consider a grading scale of anoxic damage, we evaluated the pathological findings and investigated predictive factors for bowel gangrene.

Methods: We assessed 49 patients with strangulation ileus who underwent a laparotomy between January 2004 and November 2012. Laboratory tests and the contrast computed tomography (CT) were evaluated before surgery. According to the degree of mucosal degeneration, we classified anoxic damages into the following 3 grades. Ggrade 1 shows mild mucosal degeneration with extended subepithelial space. Grade 2 shows moderate degeneration and mucosal deciduation with residual mucosa on the muscularis mucosae. Grade 3 shows severe degeneration and mucosal digestion with disintegration of lamina propria.

Results: Resected bowel specimens were obtained from the 36 patients with severe ischemia, while the remaining 13 patients avoided bowel resection. The mucosal injury showed grade 1 in 11 cases, grade 2 in 10 cases, and grade 3 in 15 cases. The patients were divided into two groups. One group included grade 1 and non-resected patients (n = 24) while the other included grades 2 and 3 (n = 25). When comparing the clinical findings for these groups, elevated creatine kinase (P = 0.017), a low base excess (P = 0.021), and decreased bowel enhancement on the contrast CT (P = 0.001) were associated with severe mucosal injury.

Conclusion: In strangulation ileus, anoxic mucosal injury progresses gradually after rapid spreading of bowel congestion. Before surgical intervention, creatine kinase, base excess, and bowel enhancement on the contrast CT could indicate the severity of anoxic damage. These biomarkers could be the predictor for bowel resection before surgery.

Figure 1

Macro- and microscopic findings of grades 1 and 2. a The mucosa of grade 1 shows a segmental color change to deep red. b The mucosal injury of grade 1 shows mild mucosal degeneration with extended subepithelial space (H & E stain, ×10). c The mucosa of grade 2 shows a segmental color change to reddish brown. d The mucosal injury of grade 2 shows moderate degeneration and mucosal deciduation with residual mucosa on the muscularis mucosae (H & E stain, ×10).

Figure 2

Macro- and microscopic findings of grade 3, and fibromuscular intimal thickening of the vasa recta. a The mucosa of grade 3 shows a segmental color change to dark red. b The mucosal injury of grade 3 shows severe degeneration and mucosal digestion with disintegration of lamina propria (H & E stain, ×10). c The microscopic finding shows fibromuscular intimal thickening of the vasa recta without occlusive thrombus (H & E stain, ×10).

Figure 3

Radiographic and pathological findings of the first case. a The contrast CT shows closed bowel loop, mesenteric congestion, and mild ascites (arrows). b Pathological findings show grade 1 mucosal injury, moderate congestion and hemorrhage (H&E stain, ×4).

Figure 4

Radiographic and pathological findings of the second case. a The contrast CT shows decreased bowel enhancement, closed bowel loop, mesenteric congestion, and mild ascites (arrows). b Pathological findings showed grade 3 mucosal injury, severe congestion and hemorrhage (H&E stain, ×4).