RESUMEN
Primary fetal hydrothorax presents a wide spectrum of severity ranging from small harmless effusions to life-threatening thoracic compression. Management of this condition is controversial. We experienced a case of non-chylous primary fetal hydrothorax not associated with hydrops or other malformations. A predominantly unilateral hydrothorax in a fetus was diagnosed by sonography at 31 weeks gestation. Repeated ultrasonographic examinations to detect development of hydrops or progression of intrapleural effusion were used to evaluate the need for intrauterine thoracentesis and to decide the optimal time for delivery. Two thoracenteses were performed. The baby was delivered at 34 weeks. Postnatal intubation was carried out in the baby, and then chest tube placement was performed and resulted in the collection of 805ml of serous fluid. Sustained intubation was necessary for 16 days because of developing respiratory distress as a result of prematurity and recurrent pleural fluid accumulation. The baby did well after postnatal evacuation of the intrapleural fluid. Pre and postnatal investigation to find the pathophysiological mechanism leading to hydrothorax were negative. We conclude that non-chylous primary fetal hydrothorax is generally associated with a favorable outcome.