Free Intra-Abdominal Air without Peritoneal Perforation after TEM: A Report of Two Cases

Transanal endoscopic microsurgery (TEM) is a minimally invasive treatment modality for a variety of rectal lesions. Due to its minimally invasive nature, TEM has emerged as a safe method. Among most threatening complications are hemorrhage and peritoneal perforation. We report on two patients who demonstrated intra-abdominal free air on an erect chest X-ray after TEM procedure without other findings of a pneumoperitoneum. We hypothesize that due to the combination of elevated pressures in the retroperitoneal cavity and decreased integrity of the retroperitoneal barrier, insufflated CO 2 gas can diffuse into the intraperitoneal cavity. Conservative treatment should be considered in patients with free intra-abdominal air postoperatively. However, there should be no suspicion of peritoneal entry during the procedure and the patient should be in generally good condition without severe abdominal symptoms.