Bowel obstruction may be classified by 5 different classification methods including: Open and closed, incomplete and complete, extrinsic, intrinsic and intraluminal, true and pseudo-obstruction, and finally, small bowel and large bowel. In this chapter, the extrinsic, intrinsic and intraluminal classification method will be used.
Bowel obstruction may be classified as follows:[1][2]
Open or closed bowel
Open type of bowel obstruction refers to an obstruction at a single location where the rest of the bowel is patent. A closed bowel obstruction refers to an obstruction occurring at two locations, so that there is no proximal or distal outlet.
Complete or incomplete obstruction
Obstructions can either completely occlude the lumen of the bowel, or can partially (incompletely) occlude the bowel.
Extrinsic, intrinsic/intramural or intraluminal obstruction
An obstruction may be due to an external cause, for example, a tumor that pushes on the bowel from the outside.
An obstruction may be caused by an intrinsic (intramural) wall abnormality, for example, a tumor or stricture or hematoma.
Small bowel obstruction include obstructions that occur along the duodenum up to the ileocecal junction, obstructions beyond this junction are classified as large bowel obstructions. A subset of large bowel obstruction includes outlet obstructions.
True or pseudo-obstruction
Ogilvie's syndrome and adynamic (paralytic) ileus represent pseudo-obstructions, and are not true mechanical obstructions as the bowel is dilated and patent but intestinal contents are not able to pass.
Bowel obstruction classification algorithm:
Bowel obstruction classification
Open or Closed
Large bowel or Small bowel
Extrinsic or Intrinsic or Intraluminal
Complete or Incomplete
True or Pseudo obstruction
Outlet obstruction (a subset of large bowel obstruction)
↑Mucha P (1987). "Small intestinal obstruction". Surg. Clin. North Am. 67 (3): 597–620. PMID3296252.
↑Miller G, Boman J, Shrier I, Gordon PH (2000). "Natural history of patients with adhesive small bowel obstruction". Br J Surg. 87 (9): 1240–7. doi:10.1046/j.1365-2168.2000.01530.x. PMID10971435.