CASE PRESENTATION: A 41-year-old female with a 1 year history of ulcerative colitis (UC) treated with vedolizumab and prednisone was admitted to critical care unit with fever, watery diarrhea and lower abdominal pain. Her other history included recurrent C difficile colitis, for which she underwent fecal microbiota transfer 2 weeks prior to admission. Vital signs showed pulse 127 beats, BP 60/35 mm Hg, temperature 101 F and respiratory rate 24. Physical examination revealed diffuse abdominal tenderness but no rebound. Laboratory evaluation was significant for leukocytosis16.8 with a lactic acid of 4.7. Urinalysis was positive and blood culture subsequently grew E. coli. CT scan demonstrated diffuse colitis, transverse colon diameter of 2.4 cm and right pyelonephritis. She was treated for septic shock and exacerbation of UC. Her condition improved over the next few days but the lactic acidosis persisted. Colonoscopy on day 7 revealed severe colitis and ulcers in the sigmoid and descending colon and mild colitis in the distal transverse colon. Biopsies were obtained from the sigmoid and descending colon. The following day, she was noted to have subcutaneous emphysema of the chest wall. CT chest, abdomen and pelvis revealed large pneumoperitoneum, pneumoretroperitonium, pneumomediastinum and pneumopericardium with air tracking all the way up into the neck. Patient remained clinically asymptomatic. She had an exploratory laparotomy and was found to have transverse colon perforation and underwent subtotal colectomy with end ileostomy.