Detection of peritoneal metastases.

The peritoneum is the largest and most complexly arranged serious membrane in the body. The potential peritoneal spaces, the peritoneal reflections forming peritoneal ligaments, mesenteries, omenta, and the natural flow of peritoneal fluid determine the route of spread of intraperitoneal fluid and consequently disease spread within the abdominal cavity. The peritoneal ligaments, mesenteries, and omenta also serve as boundaries and conduits for disease spread. Peritoneal metastases spread in four ways: (1) Direct spread along peritoneal ligaments, mesenteries and omenta to non-contiguous organs; (2) Intraperitoneal seeding via ascitic fluid; (3) Lymphatic extension; (4) Embolic haematogenous spread. Before the introduction of cross-sectional imaging, the peritoneum and its reflections could only be imaged with difficulty, often requiring invasive techniques. Computed tomography and to a lesser extent sonography and MR imaging allow us to examine the complex anatomy of the peritoneal cavity accurately, which is the key to understanding the spread of peritoneal disease. This article reviews the detection of peritoneal metastases.