VISUALIZATION OF THE EXTRAHEPATIC SEGMENT OF THE LIGAMENTUM TERES - ASIGN OF FREE-AIR ON PLAIN RADIOGRAPHS

PURPOSE: To assess visualization of the extrahepatic segment of the li gamentum teres on plain radiographs, the ligamentum teres sign, which is an indicator of pneumoperitoneum. MATERLALS AND METHODS: The ligame ntum teres was recognized in 12 patients with pneumoperitoneum. Findin gs from supine radiographs were correlated with those from oblique rad iographs and computed tomograms. RESULTS: The extrahepatic segment of the ligamentum teres, which extended between the umbilicus and the lig amentum teres notch at the inferior border of the liver, was visualize d on supine radiographs. The ligamentum teres appeared in the right up per quadrant as an obliquely oriented, straight, or slightly arcuate i nterface with a sharply demarcated inferolateral margin or as a simila rly positioned, well-defined band of soft tissue of varying length. Th e falciform ligament was also seen in six of the 12 patients as a long , thin line that ran vertically to the right of the midline and joined the ligamentum teres caudally near or at the umbilicus. Even though t here were other signs of pneumoperitoneum in all cases, the ligamentum teres sign was the most prominent in three cases. CONCLUSION: Visuali zation of the extrahepatic segment of the ligamentum teres on supine r adiographs requires the anterior accumulation of extraluminal, intrape ritoneal gas and is another sign of moderate to massive amounts of fre e air.