 Surgery may also be required for complications such as obstructions, fistulas, or abscesses, or if the disease does not respond to drugs.After the first surgery, Crohn's usually comes back at the site where the diseased intestine was removed and the healthy ends were rejoined, however it can come back in other locations.After a resection, scar tissue builds up, which can cause strictures, which form when the intestines become too small to allow excrement to pass through easily, which can lead to a blockage.