A 42 year old woman underwent a laparoscopic retrocolic retrogastric Roux en Y gastric bypass in 2018. This was was complicated by chronic, refractory marginal ulcers with a severe anastomotic stricture in spite of medical therapy and serial endoscopic balloon dilations. The patient was consented for elective laparoscopic gastrojejunostomy revision, which was performed without intraoperative complications. However, although she was initially doing well, on post-operative day #2 the patient developed significant diarrhea, abdominal pain, a surgical fever, sinus tachycardia, hypotension, and hypoxia consistent with positive Systemic Inflammatory Response Syndrome (SIRS) criteria. A CT scan was not obtained on purpose due to the gravity of the situation and her sudden decompensation. The patient was taken to the operating room for an emergency exploratory laparoscopy converted to laparotomy with intraoperative upper endoscopy which confirmed that there was no anastomotic leak. However, a significant case of segmental, right-sided toxic megacolon was identified despite having tested negative for Clostridium difficile assay earlier. A laparoscopic right hemicolectomy was performed immediately without complications. A drain was placed and she was started on appropriate antibiotics. The pathology specimen results were consistent with right colonic ischemia with pseudomembranes but without a perforation. The patient recovered well and was discharged to home 4 days later on a full liquid diet, and on antibiotics.