Introduction: We retrospectively reviewed the CT findings of the acute abdomen patients examined in the last two years to investigate the frequency of a new CT sign of intestinal infarction, the pneumoretroperitoneum, and its association with other CT findings highly suggestive of this condition.
Material and methods: The CT findings of 60 patients with diagnostic confirmation of intestinal infarction were retrospectively reviewed. CT was performed without (no. = 55) and with (no. = 5) oral administration of contrast material and without (no. = 3) and with (no. = 57) the i.v. injection of nonionic contrast agents in repeated 50 mL boluses. To assess the specificity of this sign, we selected a control group of 400 patients submitted to CT for acute abdomen, but not blunt trauma; 19 of these patients had pneumoretroperitoneum.
Results: Pneumoperitoneum was found in five patients with intestinal infarction; it was an isolated sign in two cases and it was associated with few small perihepatic air bubbles in one case. Finally, it was associated with highly suggestive findings of late intestinal infarction in the other two cases. All cases of pneumoretroperitoneum in the control group had been correctly referred to other diseases by previous plain film and/or CT findings and surgery and/or endoscopy confirmed this diagnosis.
Discussion and conclusions: Pneumoretroperitoneum has been described as a complication of different benign or severe disorders; prompt recognition of its origin is essential since surgical and/or septic conditions may be involved. However, if the patient's history is negative for abdominal trauma, gastroduodenal ulcer or sepsis, pneumoretroperitoneum is generally cured with conservative treatment. Intestinal infarction or severe ischemia, a usually surgical conditions, should be considered among the different causes of pneumoretroperitoneum alone or associated with pneumoperitoneum or with highly suggestive late findings of infarction such as portal venous gas or pneumatosis intestinalis. This sign had a non-negligible incidence in intestinal infarction in our review (8.5%), but it should be known of and sought with specific window setting to enhance gas depiction on CT images to avoid false negatives.