We present the case of an 82-year-old woman admitted in the intensive care unit with a septic shock caused by a liver abscess. She underwent an emergency laparotomy for abscess drainage and microbiological sampling. In the early postoperative period, she developed a massive subcutaneous emphysema (SE) extending from the abdomen to the head, without obvious cause. A surgical complication was suspected; thus, the patient underwent a second laparotomy which revealed a perforated peritonitis. SE is a rare presentation of perforated peritonitis, which should be known by critical care physicians in order to avoid a misdiagnosis of this life-threatening pathology.