| Grade | Description | Radiographic criteria | Operative criteria |
| I | Partial SBO | Minimal intestinal distension | Minimal intestinal distension with no evidence of obstruction |
| II | Complete SBO; bowel viable and not compromised | Intestinal distension with transition point without bowel compromise | Intestinal distension with transition point; no evidence of bowel compromise |
| III | Complete SBO with compromised but viable bowel | Intestinal distension with transition point, no distal contrast flow, evidence of complete obstruction or impending bowel compromise | Intestinal distention with impending bowel compromise |
| IV | Complete SBO with nonviable bowel or perforation with localized spillage | Evidence of localized perforation or free air; bowel distension with free air or free fluid | Intestinal distension with localized perforation or free fluid |
| V | SB perforation with diffuse peritoneal contamination | Bowel perforation with free air and free fluid | Intestinal distension with perforation, free fluid, and evidence of diffuse peritonitis |
