Grade	AAST disease grade	Diagnosis	Management	References
I	Partial SBO	CT scan of abdomen and pelvis Water soluble contrast follow through to rule out complete adhesive small bowel obstruction (ASBO) and predict need for surgery	Initial non-operative management. Water-soluble contrast follow through to rule out complete ASBO and predict the need for surgery. Surgery recommended after 3 days without resolution. Patients with SBO should generally be admitted to a surgical service	1 2 3 4 5 6
II	Complete SBO; bowel viable and not compromised	CT scan of abdomen and pelvis Water soluble contrast follow through to rule out complete ASBO and predict need for surgery	Initial non-operative management. Water-soluble contrast follow through to rule out complete ASBO and predict the need for surgery. Surgery recommended after 3 days without resolution. Patients with SBO should generally be admitted to a surgical service	1 2 3 4 5 6
III	Complete SBO with compromised but viable bowel	CT scan of abdomen and pelvis Water soluble contrast follow through to rule out complete ASBO and predict need for surgery	Operative management. Open surgery is preferred method. Laparoscopic approach can be attempted in select cases.	1 2 3 4 5 6
IV	Complete SBO with non-viable bowel or perforation with localized spillage	CT scan of abdomen and pelvis	Operative management. Open surgery is preferred method. Laparoscopic approach can be attempted in select cases. Patients with SBO should generally be admitted to a surgical service.	1 2 3 4 5 6
V	Small bowel perforation with diffused peritoneal contamination	CT scan of abdomen and pelvis	Operative management. Open surgery is preferred method. Laparoscopic approach can be attempted in select cases. Patients with SBO should generally be admitted to a surgical service.	1 2 3 4 5 6