A bowel obstruction happens when either your small or large intestine is partly or completely blocked. The blockage prevents food, fluids, and gas from moving through the intestines in the normal way. The blockage may cause severe pain that comes and goes.
This topic covers a blockage caused by tumors, scar tissue, or twisting or narrowing of the intestines. It does not cover ileus, which most commonly happens after surgery on the belly (abdominal surgery).
What causes a bowel obstruction?
Tumors, scar tissue (adhesions), or twisting or narrowing of the intestines can cause a bowel obstruction. These are called mechanical obstructions .
In the small intestine, scar tissue is most often the cause. Other causes include hernias and Crohn's disease, which can twist or narrow the intestine, and tumors, which can block the intestine. A blockage also can happen if one part of the intestine folds like a telescope into another part, which is called intussusception.