CT findings in acute peritonitis: a pattern-based approach

Many inflammatory and infectious entities may acutely affect the peritoneum causing a thickening of its layers. Unfortunately, several acute peritoneal diseases can have overlapping features, both clinically and at imaging. Therefore, the awareness of the clinical context, although useful, may be sometimes insufficient to identify the underlying cause. This article provides a specific computed tomography-based approach including morphologic characteristics of peritoneal thickening (e.g., smooth, irregular, or nodular) and ancillary findings to narrow the differential diagnosis of acute peritonitis.Computed tomography (CT) became an important tool in the detection and characterization of acute abdominal involvement with the development of multidetector CT (MDCT) scanners. This technology makes the acquisition of isotropic data possible and affords the capability of performing high-resolution multiplanar reconstructions (1). Thus, CT imaging is often the initial modality in acute abdomen in a significant proportion of patients, and radiologists should have a high level of suspicion in detection and interpretation of peritoneal abnormalities.As a wide variety of acute peritoneal diseases may present with similar clinical features, the clinicians ask the interpreting radiologist to provide a concise and focused differential diagnosis. However, several specific entities may manifest with overlapping CT findings.This article provides an overview of MDCT appearances of acute peritoneal diseases based on the peritoneal thickening pattern and a detailed analysis of the associated findings.