Risk Factors For Ovarian Hyperstimulation Syndrome Research Articles

Ovarian Hyperstimulation Syndrome (OHSS): A Narrative Review and Legal Implications.

Infertility is a highly meaningful issue with potentially life-changing consequences, and its incidence has been growing worldwide. Assisted reproductive technology (ART) has made giant strides in terms of treating many infertility conditions, despite the risk of developing ovarian hyperstimulation syndrome (OHSS), a potentially life-threatening complication. This narrative review draws upon scientific articles found in the PubMed database. The search spanned the 1990-2024 period. Search strings used included "OHSS" or "ovarian hyperstimulation" and "IVF" and "GnRH" and "hCG"; 1098 results were retrieved and were ultimately narrowed down to 111 suitable sources, i.e., relevant articles dealing with the condition's underlying dynamics, management pathways, and evidence-based criteria and guidelines, crucial both from a clinical perspective and from the standpoint of medicolegal tenability. The following features constitute OHSS risk factors: young age, low body weight, and polycystic ovarian syndrome (PCOS), among others. GnRH antagonist can substantially lower the risk of severe OHSS, compared to the long protocol with a gonadotropin-releasing hormone (GnRH) agonist. However, a mild or moderate form of OHSS is also possible if the antagonist protocol is used, especially when hCG is used for the final maturation of oocytes. For women at risk of OHSS, GnRH agonist trigger and the freeze-all strategy is advisable. OHSS is one of the most frequent complications, with a 30% rate in IVF cycles. Providing effective care for OHSS patients begins with early diagnosis, while also evaluating for comorbidities and complications. In addition to that, we should pay more attention to the psychological component of this complication and of infertility as a whole. Compliance with guidelines and evidence-based best practices is essential for medicolegal tenability.

Severe Early-Onset Intrahepatic Cholestasis of Pregnancy Following Ovarian Hyperstimulation Syndrome with Pulmonary Presentation after In Vitro Fertilization: Case Report and Systematic Review of Case Reports.

Intrahepatic cholestasis of pregnancy (ICP) is the most common pregnancy-related liver disease, usually presented in the third trimester with pruritus, elevated transaminase, and serum total bile acids. Evidence shows that it can be developed in the first trimester, more commonly after in vitro fertilization (IVF) procedures, with the presence of ovarian hyperstimulation syndrome (OHSS). A literature search was conducted in the PubMed/MEDLINE database of case reports/studies reporting early-onset ICP in spontaneous and IVF pregnancies published until July 2023. Thirty articles on early-onset ICP were included in the review analysis, with 19 patients who developed ICP in spontaneous pregnancy and 15 patients who developed ICP in IVF pregnancies with or without OHSS. Cases of 1st and 2nd trimester ICP in terms of "early-onset" ICP were pooled to gather additional findings. Proper monitoring should be applied even before expected pregnancy and during IVF procedures in patients with known risk factors for OHSS and ICP development (patient and family history), with proper progesterone supplementation dosage and genetic testing in case of ICP recurrence.

Dose Nomogram of Individualization of the Initial Follicle-Stimulating Hormone Dosage for Patients with Polycystic Ovary Syndrome Undergoing IVF/ICSI with the GnRH-Ant Protocol: A Retrospective Cohort Study.

For high responders with polycystic ovary syndrome (PCOS), there is no clear recommendation for the initial follicle-stimulating hormone (FSH) dosage to ensure an optimal number of retrieved oocytes and avoid ovarian hyperstimulation syndrome (OHSS). The aim of this study was to determine the ideal initial FSH dosage of in patients with PCOS undergoing in vitro fertilization (IVF)/intracytoplasmic sperm injection (ICSI) using the gonadotropin-releasing hormone antagonist (GnRH-ant) protocol to obtain the optimal number of retrieved oocytes and minimize the risk of OHSS. The data of 1898 patients with PCOS aged 20-40years from January 2017 to December 2020 were retrospectively analyzed to explore the factors related to the number of retrieved oocytes. Statistically significant variables were used to construct a dose nomogram and it was then validated using an independent cohort of patients with PCOS from January 2021 to December 2021. Multivariate analyses demonstrated that body mass index (BMI) was the most significant factor to predict the number of retrieved oocytes compared to body weight (BW) and body surface area (BSA). Among patients with PCOS aged 20-40years undergoing their first IVF cycles with the GnRH-ant protocol, age was not a significant predictor of the initial FSH dosage. We developed a nomogram based on BMI, basal FSH, basal luteinizing hormone (bLH), anti-Müllerian hormone (AMH), and antral follicle count (AFC) to calculate the ideal initial FSH dosage for patients with PCOS undergoing IVF/ICSI using the GnRH-ant protocol. In addition, low BMI and high bLH and AMH levels and AFC appear to be risk factors for OHSS. We clearly demonstrated that the initial FSH dosage for patients with PCOS undergoing IVF/ICSI with the GnRH-ant protocol may be calculated on the basis of the woman's BMI and ovarian reserve markers. The nomogram will help guide clinicians in the selection of the most appropriate initial FSH dose in the future.

Cryopreservation as a strategy for prevention of ovarian hyperstimulation syndrome in a public assisted reproduction service in São Paulo - Brazil.

This study aimed to evaluate the prevalence of ovarian hyperstimulation syndrome (OHSS) and associated risk factors in patients undergoing fertilization cycles at risk of OHSS (≥15 antral follicles or ≥15 oocytes aspirated) and submitted to cryopreservation of all embryos in the Human Reproduction Service of the Pérola Byington Hospital (Referral Center for Women's Health) in São Paulo, SP, Brazil. This cross-sectional, institutional, descriptive study of secondary data from patients' charts enrolled in the Assisted Reproduction Service of the Pérola Byington Hospital at risk of OHSS after controlled ovarian stimulation and submitted to cryopreservation of all embryos was conducted between January 2015 and September 2017. OHSS occurred in 47.5% of cycles, all with mild severity, and there were no moderate or severe cases of OHSS. The cryopreservation of all embryos is associated with a reduction in moderate and severe forms of OHSS. Risk factors for OHSS should be evaluated prior to initiation of treatment, with less intense stimulation protocols accordingly.

Effect and Relationship of Seasons on the High Risk of Ovarian Hyperstimulation Syndrome After Oocyte Retrieval in Patients With Polycystic Ovary Syndrome.

ObjectiveTo investigate the effect of seasons on the incidence of high risk of ovarian hyperstimulation syndrome (OHSS) after in oocyte retrieval in patients with polycystic ovarian syndrome (PCOS) and to establish a nomogram to predict the risk of OHSS.DesignSingle-center, retrospective study.SettingUniversity-affiliated reproductive medicine center.Patient(s)A total of 2,030 infertility patients with PCOS underwent the follicular phase long-acting long protocol IVF/ICSI in the reproductive medicine center from January 2017 to December 2019.Intervention(s)None.Main outcome measure(s)Logistic regression analysis was used to analyze the factors associated with a high risk of OHSS. We established a nomogram to predict the risk of OHSS in infertility patients with PCOS after oocyte retrieval.Result(s)The incidence of patients at high risk of OHSS was significantly different from season-to-season and was especially higher in the summer and winter. Multivariate logistic analysis showed that gonadotropin dosage, number of retrieved oocytes, estradiol level, average bilateral ovarian diameter on the day human chorionic gonadotropin was administered, type of infertility, and average temperature were independent risk factors for OHSS after oocyte retrieval in PCOS patients. Based on the above independent risk factors, we constructed a prediction model for OHSS risk. To evaluate the efficiency of the prediction model, we calculated the C-index (0.849), area under the receiver operating characteristic curve (0.849), and internal validation C-index (0.846). Decision curve analysis suggested that the prediction model exhibited significant net benefits.Conclusion(s)The incidence of PCOS patients at high risk for OHSS after oocyte retrieval fluctuated with seasonal temperature changes, and was significantly higher in extreme climates. The prediction model had favorable predictive performance and clinical application value.

Factors Associated with Ovarian Hyperstimulation Syndrome (OHSS) Severity in Women With Polycystic Ovary Syndrome Undergoing IVF/ICSI.

IntroductionAge, polycystic ovary syndrome (PCOS), low body mass index (BMI), high antral follicle count (AFC), increased anti-Muller hormone (AMH) levels, and elevated serum estradiol (E2) concentrations are risk factors for ovarian hyperstimulation syndrome (OHSS). However, data on the relationship between risk factors and OHSS severity in patients with PCOS are rare.ObjectiveThis retrospective study examined the risk factors for OHSS and their effect on OHSS severity in patients with PCOS undergoing in vitro fertilization (IVF)/intracytoplasmic sperm injection (ICSI).MethodThe records of 2,699 women were reviewed and included in this study. These women were diagnosed with PCOS during their first IVF/ICSI cycle between January 2010 and December 2017. We analyzed the association between each of the interrogated risk factors (including female age, BMI, AFC, basal serum E2, and the number of oocytes retrieved) and OHSS. The effects of each risk factor on OHSS severity were further explored. Logistic regression was performed as part of the above analysis.ResultsOf the 2,699 women with PCOS who underwent assisted reproductive technology (ART), 75.2% had a normal response to controlled ovarian hyperstimulation (COH), while 24.8% developed OHSS. All OHSS patients were younger and had lower BMIs and basal serum follicle-stimulating hormone (FSH) and E2 levels but higher AFCs than those in the normal group. AFC demonstrated a strong correlation with OHSS, with a cutoff value of 24 in patients with PCOS. A total of 19.5% of the patients had mild OHSS, while 80.5% had moderate OHSS. Compared with those in the moderate OHSS group, those in the mild OHSS group were older and had higher basal serum FSH levels and lower serum E2 and T levels. However, BMI and AFC were not different between the mild and moderate OHSS groups. Basal serum E2 showed a strong correlation with OHSS severity, with a cutoff value of 37.94 pg/ml.ConclusionsAFC is a strong marker of OHSS, and basal serum E2 is the best predictor of OHSS severity in women with PCOS undergoing IVF treatment.

Effect of Low-dose Human Chorionic Gonadotropin on the Prevention of Ovarian Hyperstimulation Syndrome and in Vitro Fertilization Outcome

Background & aim: Ovarian hyperstimulation syndrome (OHSS) is a rare but most potentially life-threatening disorder in women under in vitro fertilization (IVF). This study aimed to determine the effect of low-dose human chorionic gonadotropin (hCG) on the prevention of OHSS and IVF outcome. Methods: This single-blind non-randomized clinical trial was performed from October 2008 to November 2012 in Motahari Hospital, Urmia, Iran. Overall, 202 infertile women undergoing IVF treatment were divided into two groups based on OHSS risk factors. Then, 87 women with serum estradiol level of 5000-8000 pg/ml received 5000 units of intramuscular hCG, and 115 women with serum estradiol level of > 8000 pg/ml, who were at high risk for OHSS, received 1600 units of hCG. Data were analyzed using independent t-test and Chi-square test in SPSS, version 16. Results: There were no significant differences in age, infertility duration, infertility factor, quality of embryo, pregnancy rate and number of abortions and OHSS rate between the groups (P>0.05). The group that received 1600 units of hCG was in a better condition regarding the mean number of ova (11.45±5.41 versus 9.24±4.24; P=0.01), mean number of good quality ova (11.10± 5.47 versus 8.68± 4.03; P=0.001), and mean number of embryos (7.38± 4.24 versus 5.53± 2.85; P=0.001). There was no significant difference in the rate of OHSS incidence and cancellation of embryo transfer between the two groups (1600 and 5000 units). Conclusion: Overall, the current study indicated that prescribing 1600 units of hCG in women who are at risk of hypersensitivity reaction may induce similar or perhaps better results regarding the quantity and quality of ova and embryos, however, OHSS risk is not completely eliminated by using a lower dose of hCG. It is therefore suggested to perform randomized clinical trials with greater sample size to verify these results.

Avoiding OHSS: Controlled Ovarian Low-Dose Stimulation in Women with PCOS.

The polycystic ovary syndrome is a common endocrine disorder which influences outcome and potential risks involved with controlled ovarian stimulation for artificial reproductive techniques (ART). Concrete practical recommendations for the dosage of gonadotropins, the preferred protocol and preventive methods to avoid ovarian hyperstimulation syndrome (OHSS) are lacking. We present retrospective data of 235 individually calculated gonadotropin low-dose stimulations for ART in a single center from 2012 to 2014. Clinical data and outcome parameter of patients diagnosed with PCOS according to Rotterdam criteria (n = 39) were compared with patients without PCOS (n = 196). The starting dose of gonadotropins was individually calculated depending on patients' age, BMI, ovarian reserve, ovarian response in previous cycles, and diagnostic criteria of PCOS. Mean age and duration of infertility did not differ between the groups, whereas mean BMI (p = 0.007) and AMH (p < 0.001) were higher in the PCOS-group. A lower mean FSH-starting and maximum dose was administered to women with PCOS (p < 0.001). The biochemical pregnancy rate of 42.4 % and the clinical pregnancy rate of 32.2 % for PCOS-patients did not differ from those of the control group (42.2 % and 34.4 % respectively). Neither mild, nor moderate or severe manifestation of OHSS occurred significantly more often in patients with PCOS. Our study supports the use of a calculated low-dose FSH-stimulation strategy in ART for patients with PCOS. Further randomized clinical trials should confirm this strategy and lead to define individual risk factors for OHSS, which can be used for recommendation of safer ART-techniques like in vitro maturation.

Severe ovarian hyperstimulation syndrome in spontaneous pregnancy treated successfully with cabergoline

Ovarian hyperstimulation syndrome (OHSS) is a relatively common complication in infertile patients treated with exogenous gonadotropins. Ovarian hyperstimulation in spontaneous pregnancies is a rare but possible. The pathogenesis of spontaneous OHSS is not well known. Risk factors for OHSS are young age, polycystic ovaries, low body mass index, high gonadotropin dose, increased estradiol and human chorionic gonadotropin levels, multiple pregnancy, OHSS history, molar pregnancy and hypothyroidism. In this report we present a case of severe spontaneous OHSS with a brief summary of the literature. She was hospitalized and treated in the clinic with the diagnosis of severe OHSS accompanying spontaneous pregnancy.

The development of ovarian hyperstimulation syndrome in the implementation of assisted reproductive technology in women with a background of endocrine pathology

Known factors of the development of ovarian hyperstimulation syndrome (OHSS) are not informative enough, if considered independently. This is confirmed by the absence of initial predictors in cases of severe OHSS and, in contrast, not clinically apparent manifestations in patients seemingly having high risk of this pathology. These circumstances demand investigation of additional prognostic parameters of the OHSS.Purpose: To find out additional OHSS risk factors alongside with the previously known ones in the course of implementation of assisted reproductive technologies (ART) in patients having initial metabolic and hormonal disorders.Investigation data and methods: Retrospective analysis of clinical laboratory and functional parameters of hormonal and metabolic state of 133 women suffering OHSS was held. Classification by Schenker, 1995, was used to detect the diagnosis. Control group consisted of 347 women with the unverified OHSS. Basic and control study groups were similar in age and in number of mild and long protocols of ovarian stimulation held.Results and their discussion: A significant correlation dependence was revealed between the fact of the OHSS development and some indicators of hormonal and metabolic state: HOMA index of insulin resistance; thyroid parameters: thyroid stimulating hormone (TSH), free thyroxine (fT4), thyroid peroxidase antibodies (AbTPO); and level of prolactin. The revealed correlation dependence of the OHSS development on the above parameters allows to use them for determination of the OHSS risk group and taking measures to prevent this complication of the ART.

Neutrophil to lymphocyte ratio is superior to platelet to lymphocyte ratio as an early predictor of moderate/severe ovarian hyperstimulation syndrome

Ovarian hyperstimulation syndrome (OHSS) is a state of exaggerated inflammatory response during controlled ovarian hyperstimulation (COH). Neutrophil:lymphocyte ratio (NLR) and platelet:lymphocyte ratio (PLR) are known to reflect systemic inflammation. The aim of this study was to investigate whether these inflammatory markers could be used as reliable markers in the early prediction of moderate-to-severe OHSS. The study group consisted of 54 patients who developed moderate-to-severe OHSS and the control group was 54 patients who did not develop OHSS undergoing IVF/ICSI. NLR and PLR were calculated from complete blood counts before the COH. NLR and PLR were significantly elevated in the OHSS group compared with the controls (3.2 ± 0.9 and 182.9 ± 49.8 vs 1.8 ± 0.5 and 160.6 ± 48.5, respectively) (p < 0.05, for all). However, only NLR had positive associations between OHSS risk factors (p < 0.05, for all). NLR was superior to PLR as an early predictor of OHSS with an area under the ROC curve of 0.91 (sensitivity = 85% and specificity = 78%). In conclusion, we found that NLR can be used as an early marker of OHSS.

The effect of cabergoline on folicular microenviroment profile in patients with high risk of OHSS

The aim of this study to evaluate the effect of cabergoline on follicular microenvironment by measuring follicular fluid (FF) insulin like growth hormone –I (IGF-I), antimullerian hormone (AMH), inhibin B and hepatocyte growth factor (HGF) levels in women with PCOS and high risk of ovarian hyperstimulation syndrome (OHSS). In this prospective cohort study, 41 women with PCOS undergoing controlled ovarian hyperstimulation for assisted reproduction and having the high risk factors for OHSS are included. The women in the study group (n = 15) received cabergoline for OHSS prevention while the women in the control did not received any medications for OHSS prevention. FF samples were collected during oocyte pick-up procedure for all women were determined using commercially available ELISA kits. Concentrations of FF IGF-I, AMH, inhibin B and HGF were assessed. In the study group FF AMH (2.96 ± 1.27 versus 1.91 ± 0.64 ng/mL), Inhibin B (1339.47 ± 198.56 versus 1200.09 ± 133.64 pg/mL), HGF (5623.21 ± 2411.09 versus 3787.42 ± 2269.89 pg/mL) and IGF-I (298.60 ± 37.80 versus 219.90 ± 71.40 pg/mL) concentrations were significantly decreased compared with control group. Cabergolin prevents OHSS in high risk patients by disrupting FF hormone microenvironment.

Serum anti-Müllerian hormone and antral follicle count as predictive markers of OHSS in ART cycles

To evaluate predictive role of day-3 serum anti-Müllerian hormone (AMH) levels and antral follicle count (AFC) in ovarian hyperstimulation syndrome (OHSS) in patients undergoing IVF/ICSI cycles. Forty-one women with moderate/severe OHSS and 41 age matched women without OHSS were compared to evaluate the predictive value of certain risk factors for OHSS. AFC, and E(2), FSH, LH, AMH, inhibin-B levels measured on day3 of the menstrual cycle before controlled ovarian hyperstimulation. Mean FSH was significantly lower (p < 0.0001); and mean LH, AFC and AMH were significantly higher in women with OHSS compared to women without OHSS (p = 0.049, p < 0.0001 and p < 0.0001, respectively). There was no significant difference in inhibin B (p = 0.112) and estradiol (p = 0.706) between the groups. The ROC area under curve (AUC) for AMH presented the largest AUC among the listed risk factors. AMH (AUC = 0.87) and AFC (AUC = 0.74) had moderate accuracy for predicting OHSS while Inhibin B (AUC = 0.58) and LH (AUC = 0.61) had low accuracy. The cut-off value for AMH 3.3ng/mL provided the highest sensitivity (90%) and specificity (71%) for predicting OHSS. It's positive (PPV) and negative predictive values (NPV) were 61% and 94%, respectively. The cut-off value for AFC was 8 with 78% sensitivity, 65% specificity, 52% PPV and 86% NPV. Measurement of basal serum AMH and AFC can be used to determine the women with high risk for OHSS.

Le syndrome d’hyperstimulation ovarienne

The ovarian hyperstimulation syndrome (OHSS) is a complication of controlled ovarian hyperstimulation (COH) protocols performed in women undergoing assisted reproductive technologies. This syndrome is characterized by multiple intra-ovarian corpus luteum and constitution of a third space that can lead to a life-threatening situation. Although the pathophysiology remains unclear, vascular endothelial growth factor (VEGF) and other cytokines, secreted under the influence of exogenous gonadotrophins administered for COH, are involved in increasing capillary permeability. The clinical course varies from increased size of the ovaries to anasarca with potentially fatal circulatory dysfunction. Mortality rate, though not accurately quantified, is significant (1/45 000 to 1/500 000) and mostly due to thromboembolic complications. The only effective treatment is prevention, by adapting ovarian stimulation protocols to OHSS risk factors. There are no specific treatments and therapy is mainly symptomatic until the condition resolves spontaneously.

Symptomatic Isolated Pleural Effusion as an Atypical Presentation of Ovarian Hyperstimulation Syndrome

Ovarian hyperstimulation syndrome (OHSS) presents in ~33% of ovarian stimulation cycles with clinical manifestations varying from mild to severe. Its pathogenesis is unknown. Pleural effusion is reported in ~10% of severe OHSS cases and is usually associated with marked ascites. The isolated finding of pleural effusions without ascites, as the main presenting symptom of OHSS is not frequently reported and its pathogenesis is also unknown. We describe two unusual cases of OHSS where dyspnea secondary to unilateral pleural effusion was the only presenting symptom. By reporting our experience, we would like to heighten physicians' awareness in detecting these cases early, as it is our belief that the incidence of pleural effusion in the absence of most commonly recognized risk factors for OHSS may be underestimated and may significantly compromise the health of the patient if treatment is not initiated in a reasonable amount of time.

Ovarian Hyperstimulation Syndrome: Definition, Incidence, and Classification

Ovarian hyperstimulation syndrome (OHSS) is a iatrogenic complication of controlled ovarian stimulation. Although considered uncommon, the severe form is potentially fatal. Different clinical classifications have been developed through the years. No matter whether it is termed "grade C" or "critical" OHSS, life-threatening events may develop. Hence it is prudent to recognize the population at risk. Several risk factors for OHSS have been identified; some are considered major risk factors such as polycystic ovary syndrome; others are less well defined. Preventive measures could be taken before and during the treatment cycle while taking into consideration the patient's characteristics and the various treatment options and approaches that currently exist.

Elevated serum müllerian-inhibiting substance may be a marker for ovarian hyperstimulation syndrome in normal women undergoing in vitro fertilization

We identified patients who experienced ovarian hyperstimulation syndrome (OHSS) (n = 16) and compared their baseline pretreatment levels of müllerian-inhibiting substance (MIS) to age- and weight-matched patients with normal responses to gonadotropins (n = 14). Baseline serum MIS in patients with OHSS were sixfold higher than those seen in normal controls (3.62 +/- 0.87 vs. 0.63 +/- 0.09 ng/mL; P=.0036), indicating that MIS could potentially serve as a useful marker for identifying patients at risk for OHSS.

Inversion Ratio of Gonadotropins Activity in Ovulation Induction in Women at Risk of Developing Ovarian Hyperstimulation Syndrome: Preliminary Results

Ovarian hyperstimulation syndrome (OHSS) is a potential life-threatening complication of treatment for infertility. The purpose of this study was to evaluate a protocol of ovarian stimulation in women at risk of developing OHSS, performing the inversion ratio of FSH/LH activity in the mid-follicular phase, through the use of LH activity in the form of low-dose hCG. Case series in a tertiary care center. Seven patients having their first cycle of in-vitro fertilization cancelled because of high risk at developing OHSS (> 30 follicles, E2 > 5,000 pg/mL) were included in this study. Ovarian stimulation was performed with recombinant FSH, 150 IU daily, commencing on day 2 after spontaneous or progestagen-induced withdrawal bleeding. Ovarian response was monitored by pelvic ultrasonography and daily blood samples. When the leading follicle had a size of at least 13 mm, we performed the inversion ratio of FSH/LH activity, by switching the stimulation from recombinant FSH to hCG alone, at the dose of 200 IU intramuscularly daily. At this moment the GnRH antagonist, 0.25 mg cetrotide subcutaneously once daily, was added to the stimulation regimen. When at least three follicles > 17 mm had developed, final oocyte maturation was triggered with 5,000 IU of hCG intramuscularly. Follicular aspiration was performed 35-36 hours later. The outcomes were evaluated in terms of cancellation rate, estradiol concentrations on the day of hCG injection to trigger oocyte maturation, number of mature oocytes retrieved, fertilization rate and pregnancy rate. The age of the women ranged from 27 to 37 years (mean: 33.7). In all patients, risk factors for OHSS were not observed during ovarian stimulation. All treatment cycles produced developing embryos, and there were no cycles cancelled. In all cases, cetrotide and hCG administration began on day 6 of ovarian stimulation, so that the total dose of recombinant FSH administered was 750 IU for each patient. Low-dose hCG was administered for 3 days in 6 women (total dose of hCG: 600 IU, 8 days of stimulation) and for 4 days in 1 woman (total dose of hCG: 800 IU, 9 days of stimulation). Number of mature oocytes (MII) retrieved ranged from 7 to 16 (mean: 11). Estradiol concentrations on the day of hCG administration to trigger oocyte maturation ranged from 2200.5 to 3531.2 pg/mL (mean: 2984.1 pg/mL). Overall fertilization rate was 78,6%. Clinical pregnancy was observed in 2 patients (pregnancy rate: 28.5%). All of these pregnancies are ongoing. Our preliminary results suggest that an ovarian stimulation protocol with low-dose hCG to produce inversion ratio of FSH/LH activity in the mid-follicular phase, associated to a GnRH antagonist, may be an efficient, non-expensive and safe option for women at risk of developing OHSS. The reduction in the development of small follicles induced by this protocol of ovarian stimulation, may play an important role in the prevention of the syndrome. To our knowledge, this is the first report using the inversion ratio of gonadotropins activity and a GnRH antagonist to diminish the likelihood of OHSS in high-risk patients. Nevertheless, comparative and randomized clinical trials are needed to confirm our preliminary observations.

Prevention and management of ovarian hyperstimulation syndrome

Abstract Ovarian hyperstimulation syndrome (OHSS) most commonly follows human chorionic gonadotrophin (hCG) administration as part of supraphysiological ovarian stimulation in assisted conception cycles. If risk factors for OHSS are detected pretreatment, stimulation regimes should be modified. Monitoring of ovarian response during gonadotrophin stimulation may identify high-risk cycles, allowing further gonadotrophin to be withheld till the ovarian response settles to safe levels. Complete avoidance of hCG prevents OHSS, but may not be acceptable to patients. Luteal hCG exposure can be minimized by freezing all embryos or by using luteal support with progesterone in preference to hCG. Patients with moderate/severe OHSS should be admitted and receive sympathetic counselling, thrombosis prophylaxis and symptomatic treatment for pain and nausea. Oral rehydration should be encouraged, with intravenous crystalloids for cases with significant nausea. Volume expanders should be used for resistant dehydration and oliguria. Paracentesis may help patients with tense ascites. Complications may require multidisciplinary care.

Ovarian hyperstimulation syndrome

Ovarian hyperstimulation syndrome