A 68-year old female underwent removal of a 3 cm transverse colon polyp, which contained adenocarcinoma, by means of endoscopic polypectomy. She tolerated the procedure well. Unfortunately, six hours later she returned to the hospital with vague abdominal complaints. Her clinical exam revealed mild abdominal tenderness, but was not suggestive of a perforated viscus. Radiographic data revealed retroperitoneal, mediastinal, and free intraperitoneal air, along with intramural bowel wall air.