Meigs syndrome is characterized by the presence of
ascites and pleural effusion in the presence of a benign ovarian tumor.
Pseudo-Meigs syndrome presents in a similar fashion and is associated with
benign tumors of other pelvic organs. The cause of the ascites is uncertain
but may be a result of mechanical irritation of the peritoneum, venous or
lymphatic obstruction, or production of vasoactive substances by the tumor.
The development of pleural effusions, which are usually right sided and may
be massive, probably is caused by passage of ascitic fluid via
transdiaphragmatic lymphatics or directly via diaphragmatic defects.
Classically, the ascites and pleural effusions disappear following tumor
removal. Development of ascites may be caused by release of mediators (e.g.,
activated complements, histamines, fibrin degradation products) from the
tumor, leading to increased capillary permeability.