Chest radiograph (a) and cross-table lateral abdominal radiograph (b) of a 5-day-old former 35-week preterm infant with complex congenital heart disease following cardiac catheterization for placement of pulmonary artery flow restrictors. This 2.5-kg infant received a high dose (15.7 cc/kg) of intravascular iodinated contrast during the procedure, resulting in transient enhancement of pericardium (white arrowheads), peritoneum (white arrows), and retroperitoneum, serosa, and fascia (asterisks). This phenomenon is attributable to a high-contrast dose coupled with low renal contrast clearance, and perhaps worsened by high intravascular volumes and pressure, allowing for leakage into extracellular spaces and uptake by lymphatics. The unusual density of these soft tissues accentuated against normal fat creates the false appearance of extensive ectopic gas (pseudo-pneumoperitoneum and pseudo-subcutaneous emphysema). The enhancement gradually clears over 1 to 3 days