On occasion, an enteroenterostomy may be used to bypass an obstructed segment of small intestine involved with regional ileitis, tumor, or extensive adhesions. A great difference in diameter of the intestine that enters and exits a point of obstruction may make an end-to-end anastomosis difficult. In some patients, a side-to-side anastomosis can provide relief of the obstruction with minimum risk and without sacrificing extensive segments of small intestine. In patients who have had previous small bowel resection or regional ileitis, it may be the procedure of choice rather than a radical resection leading to further nutritional problems, despite the risk of subsequent malignancy in the involved area of enteritis. The enteroenterostomy is also used to reestablish the continuity of the small intestine after a variety of Roux-en-Y procedures.