Bilateral rib diaphragmatic angle effusion in the chest cavity may be caused by trauma, lung disease and other factors. 1. Trauma: common injuries include traffic accidents, heavy object injuries and pressure injuries, fall from height, car crash, lung contusion caused by sharp object stabbing into the chest, etc. These traumatic injuries will lead to rupture of the capillaries in the chest, which will lead to blood seepage, so the bilateral rib-diaphragm angle effusion in the chest cavity is most likely due to the accumulation of blood caused by the trauma. 2. Lung diseases: common lung diseases include tuberculosis, pneumonia, lung cancer and other diseases themselves resulting in bilateral costophrenic angle effusion. For example, pneumonia is mostly due to inflammatory exudation accumulating in the chest cavity of bilateral costal diaphragm angle; lung cancer causes proteinemia or cancer invades the pleura, which can cause bilateral costal diaphragm angle effusion. 3. Other factors: such as heart failure, the heart’s ejection ability is weakened, resulting in a reduction of blood ejection in the heart, the amount of return blood is restricted, causing edema, which can also cause bilateral rib-diaphragmatic angle effusion. If you find that there are thoracic bilateral rib diaphragm angle effusion should be promptly consulted by a specialist doctor to confirm the diagnosis and active treatment.