Atypical ovarian hyperstimulation syndrome with isolated pleural effusion but without ascites or hemoconcentration.

Ovarian hyperstimulation syndrome (OHSS) is a potentially severe complication following ovarian stimulation. It has a clinical spectrum ranging from a mild form, which accounts for most cases, to moderate and severe forms that occur rarely but deserve special attention since they are life threatening [1]. Clinical manifestations of OHSS can be classified into (1) mild, with abdominal distension; (2) moderate, with ascites; (3) severe, with apparent ascites and/or effusion (pleural, rarely pericardial); and (4) hypovolemic shock, acute renal and respiratory failure, and thrombotic disorders [2]. This syndrome is an iatrogenic disorder, which is not yet fully understood, and carries a significant risk of morbidity and mortality. Despite close monitoring during ovarian stimulation and rigid guidelines and criteria for canceling cycles, OHSS still occurs. Owing to the increased use of therapeutic strategies for infertility, the pulmonary complication of this syndrome should be suspected on clinical grounds and identified early to allow for more appropriate diagnosis and management [3]. We report a patient whose only manifestation of OHSS was unilateral pleural effusion with no ascites. A 35-year-old woman came to our hospital for in vitro fertilization and embryo transfer treatment because of bilateral tubal occlusion. She received oral pills and standard downregulation during the previous cycle before ovarian stimulation. Ovulation induction, using recombinant follicle stimulating hormone (r-FSH; 225 IU/ day for 8 days, up to a dose of 1650 IU) and human menopausal hormone (HMG; 150 IU/day for 3 days, up to a dose of 450 IU), was then started on day 3 after the cycle began. Human chorionic gonadotropin (hCG) 10,000 IU was administrated when at least two follicles were ≥ 16 mm. The level of estradiol (E2) on the day of hCG administration was 2,052 pg/mL. There were eight oocytes harvested in this cycle, and three embryos were transferred back to her uterus after oocyte retrieval. Luteal phase support was given with oral progesterone without hCG. The postoperative course was uneventful until the day she came to the emergency room (ER). Approximately 2 weeks following embryo transfer, she presented in our ER with severe dyspnea. On admission, the chest X-ray revealed a large isolated pleural effusion in the right lung (Figure 1). There was no ascites or extraordinary enlarged ovaries within her abdomen. There was no sign of hemoconcentration either. Her white blood cell (WBC) count, hemoglobin level, and hematocrit (Hct) were 15,900/μL, 13.6 g/dL, and 38.6%, ATYPICAL OVARIAN HYPERSTIMULATION SYNDROME WITH ISOLATED PLEURAL EFFUSION BUT WITHOUT ASCITES OR HEMOCONCENTRATION