ABSTRACT
This chapter presents a basic description of the pathophysiology of pleural effusion and chyle. It discusses the anatomy and embryology of the pleura and lymphatic system. The chapter overviews the clinical aspects of neonatal pleural effusions, especially chylothorax, as well as fetal pleural effusion, hemothorax, and empyema. The function of the pleural fluid is to lubricate the pleura to allow for smooth lung movement and to provide surface tension of the lung to keep the appropriate distance from the thoracic wall. The lymphatic system is a one-directional circulatory system that transfers extracellular fluid, lymph, and chyle from peripheral tissues to the subclavian vein without a central pump. Ultrasonography is a reliable diagnostic method to detect pleural effusion in neonates and children. Its use in obstetric practice as the primary method of imaging the fetal chest has led to the increasing frequency with which in utero diagnosis can be made.
