Diagnostic Complexities in a Case of Ovarian Hyperstimulation Syndrome Presented Solely as a Unilateral Massive Hydrothorax.

To describe a rare case of unilateral massive hydrothorax after controlled ovarian stimulation for IVF and to analyze the diagnostic complexities in a patient lacking both risk factors and typical features of ovarian hyperstimulation syndrome (OHSS). We present a case of a 35-year-old woman suffering from primary infertility due to a severe male factor. Admitted to hospital for dyspnea, the patient initially underwent a thoracentesis. Later, due to the recurrence of massive hydrothorax, permanent pleural drainage was placed. Recognized as a severe manifestation of the OHSS, it was treated by pleural drainage, hydration, albumin perfusion, and management of the intercurrent pregnancy, up to improvement in clinical and hematological laboratory parameters and resolution of pleural effusion and respiratory symptoms. A total of 42 l of pleural fluid was drained during the 40 days of hospitalization. Since the pathogenesis of isolated acute hydrothorax in ovarian stimulation probably lies in the presence of anatomical defects of the diaphragm, this may justify that the relationship between this pathology and the OHSS risk factors may be less close. Massive pleural effusion may exceptionally be the only clinical presentation of OHSS. A high index of suspicion is necessary to make the correct diagnosis and to promptly administer treatment.