Severe OHSS: An 'epidemic' of severe OHSS: a price we have to pay?

Induction of ovulation by gonadotrophins is one of the major developments in the treatment of infertility in the second half of the 20th century. Today, it is the treatment of choice for Ͼ40% of infertile women suffering from ovulatory failure. In addition, extracorporeal fertilization techniques, primarily in-vitro fertilization (IVF) and embryo transfer are used for mechanical problems, male factor, and unexplained infertility, and are practised widely in almost every country in the world today. Successful induction of ovulation should ideally attain as many follicles and oocytes as possible to obtain the maximal number of embryos in a single treatment cycle. This goal is achieved by using regimens employing gonadotrophin-releasing hormone (GnRH) analogues and high dose gonadotrophins. Unfortunately, these regimens are associated with a serious and potentially life-threatening medical complication, i.e. ovarian hyperstimulation syndrome (OHSS). This syndrome is expressed by a variety of clinical symptoms and signs, the underlying mechanism for which is capillary hyperpermeability mediated by ovarian-derived vasoactive substances. Severe cases present with a clinical picture of systemic capillary leakage, including massive ascites, pleural and pericardial effusions, reduced effective blood volume, oliguria, haemo-concentration, thromboembolic phenomena and, occasionally, death (Schenker and Weinstein, 1978). The exact incidence of severe OHSS in the world has not yet been determined, since most of the data on this subject derive from relatively small series. Available data, however, suggest an incidence of 0.2–1.0% of all assisted conception cycles (Smitz et al. In order to clarify this point, we conducted a multicentric study including 16 out of 19 tertiary medical centres in (Abramov et al., 1998). In this study, we reviewed medical records of all patients who were hospitalized for severe OHSS at these centres between January 1987 and December 1996. Cases of severe OHSS were selected according to the revised 2181 criteria (Golan et al., 1989; Navot et al., 1992). These include massive ascites or hydrothorax in conjunction with prominent dyspnoea, haemodynamic instability, oliguria, anasarca, liver dysfunction, adult respiratory distress syndrome (ARDS), acute renal failure, or thromboembolic phenomena. During the period of this study, a total of 73 492 IVF cycles were performed, 2902 patients were admitted for moderate OHSS, and 209 for severe OHSS. Among the latter, 163 patients (78%) were undergoing IVF, while the rest received conventional ovulation induction treatments. Most patients (94%) with severe OHSS undergoing IVF received ovulation induction by the long protocol using pituitary suppression with GnRH analaogues, followed by exogenous …