Prevention of OHSS: Current strategies and new insights

Prognostic role of follicular fluid tumor necrosis factor alpha in the risk of early ovarian hyperstimulation syndrome

BACKGROUND

Ovarian hyperstimulation syndrome (OHSS) is an iatrogenic condition characterized by capillary hyperpermeability which can be predicted by preovulatory ovarian responses such as number of follicles. A variety of cytokines are thought to be involved in pathophysiology of this syndrome.

METHODS

A prospective cohort study invloving sixty intracytoplasmic sperm injection (ICSI) patients. On the day of hCG injection, we explored the threshold of larger follicles ≥11 mm diameter with a count of ≥18 follicles for the high-risk moderate-to-severe OHSS and 13-18 follicles for the low-risk moderate-to-severe OHSS. Whereas larger follicles count of less than 13 were classified as normoresponders. Pooled follicular fluid (FF) samples of each patient were collected on the day of oocyte retrieval. Magnetic multiplex immunoassay was explored to measure the concentrations of some intrafollicular cytokines including: GM-CSF, INF-γ, TNF-α, IL-10, CXCL8/IL-8, IL-6, IL-5, IL-4, IL-2, and IL-1β. All sixty patients underwent controlled ovarian hyperstimulation (COH) with either GnRH agonist or antagonist protocols.

RESULTS

Intrafollicular TNF-α concentration was significantly different (p < 0.05) in the high-risk moderate-to-severe OHSS patients compared to low-risk moderate-to-severe OHSS patients and normoresponders. TNF-α in FF had a negative correlation with the chance of high-risk moderate-to-severe OHSS. The differences in the risk of OHSS between patients who received GnRH agonist or antagonist were not significant (p > 0.05).

CONCLUSIONS

In accordance to the negative correlation of TNF-α and high risk of early OHSS, we did not expect TNF-α to play a role in increasing vascular permeability in ovarian tissues. In addition, the risk of early moderate-to-severe OHSS was not affected by different GnRH superovulation protocols.

Pharmacokinetics and Bioavailability of the GnRH Analogs in the Form of Solution and Zn2+-Suspension After Single Subcutaneous Injection in Female Rats

BACKGROUND AND OBJECTIVES

Although many synthetic gonadoliberin analogs have been developed, only a few of them, including buserelin, were introduced into clinical practice. Dalarelin, which differs from buserelin by just one aminoacid in the position 6 (D-Ala), is not widely used so far. Gonadotropin-releasing hormone (GnRH) analogs are used to treat many different illnesses and are available in different forms like solution for injection, nasal spray, microspheres, etc. Unfortunately, none of the above drug formulations can release the hormones for 24 h. We assumed that classical suspension could solve this problem.

METHODS

Two sets of experiments were performed. In the first one, buserelin and dalarelin were injected into mature female rats in two forms: suspension, in which the analogs are bounded by Zn²⁺ ions and solution. The pharmacokinetic parameters and bioavailability of the analogs were calculated, based on their concentration in the plasma measured by high-performance liquid chromatography method (HPLC). In the second experiment, the hormones in two different forms were injected into superovulated immature female rats and then the concentration of Luteinizing hormone (LH), Follicle-stimulating hormone (FSH) and 17β-estradiol in the serum was measured by radioimmunological method.

RESULTS

The Extent of Biological Availability (EBA), calculated on the base of AUC_0-∞, showed that in the form of solution buserelin and dalarelin display, respectively, only 13 and 8 % of biological availability of their suspension counterparts. Comparing both analogs, the EBA of dalarelin was half (53 %) that of buserelin delivered in the form of solution and 83 % when they were delivered in the form of suspension. The injection of buserelin or dalarelin, in the form of solution or suspension, into superovulated female rats increased LH, FSH and estradiol concentration in the serum. However, after injection of the analogs in the form of suspension, the high concentration of LH and FSH in the serum persisted longer.

CONCLUSION

Performed studies indicate that GnRH analogs in the form of suspension have higher bioavailability than their solution counterparts. It influences the effects of their action, especially in relation to LH and FSH.

Predicting and preventing ovarian hyperstimulation syndrome (OHSS): the need for individualized not standardized treatment

Ovarian hyperstimulation syndrome (OHSS) is the most serious complication of controlled ovarian stimulation (COS) as part of assisted reproductive technologies (ART). While the safety and efficacy of ART is well established, physicians should always be aware of the risk of OHSS in patients undergoing COS, as it can be fatal. This article will briefly present the pathophysiology of OHSS, including the key role of vascular endothelial growth factor (VEGF), to provide the foundation for an overview of current techniques for the prevention of OHSS. Risk factors and predictive factors for OHSS will be presented, as recognizing these risk factors and individualizing the COS protocol appropriately is the key to the primary prevention of OHSS, as the benefits and risks of each COS strategy vary among individuals. Individualized COS (iCOS) could effectively eradicate OHSS, and the identification of hormonal, functional and genetic markers of ovarian response will facilitate iCOS. However, if iCOS is not properly applied, various preventive measures can be instituted once COS has begun, including cancelling the cycle, coasting, individualizing the human chorionic gonadotropin trigger dose or using a gonadotropin-releasing hormone (GnRH) agonist (for those using a GnRH antagonist protocol), the use of intravenous fluids at the time of oocyte retrieval, and cryopreserving/vitrifying all embryos for subsequent transfer in an unstimulated cycle. Some of these techniques have been widely adopted, despite the scarcity of data from randomized clinical trials to support their use.

Cabergoline for preventing ovarian hyperstimulation syndrome

BACKGROUND

Ovarian hyperstimulation syndrome (OHSS) is a complication resulting from administration of human chorionic gonadotrophin (hCG) in assisted reproduction technology (ART) treatment. Most case are mild, but forms of moderate or severe OHSS appear in 3% to 8% of in vitro fertilisation (IVF) cycles. Recently, the dopamine agonist cabergoline has been introduced as a secondary prevention intervention for OHSS in women at high risk of OHSS who are undergoing ART treatment.

OBJECTIVES

To assess the effectiveness and safety of cabergoline in preventing ovarian hyperstimulation syndrome (OHSS) in high-risk women undergoing ART treatment.

SEARCH METHODS

Major medical databases (Cochrane Menstrual Disorders and Subfertility Group Specialised Register of trials, CENTRAL (The Cochrane Library), MEDLINE, EMBASE and PsycINFO) were systematically searched for randomised controlled trials (RCTs) assessing the effect of cabergoline in preventing OHSS. Databases were searched up to September 2011. Registers of clinical trials, abstracts of scientific meetings and reference lists of included studies were searched. No language restrictions were applied.

SELECTION CRITERIA

RCTs which compared cabergoline with placebo, no treatment or another intervention for preventing OHSS in high-risk women were considered for inclusion. Primary outcome measures included incidence of moderate or severe OHSS and live birth rate. Secondary endpoints were clinical pregnancy rate, multiple pregnancy rate, miscarriage rate and any other adverse effects of the treatment.

DATA COLLECTION AND ANALYSIS

Two authors independently screened titles, abstracts and the full text of publications; extracted data; and assessed risk of bias. Any disagreements were resolved by consensus. Pooled results were reported as odds ratio (OR) and 95% confidence interval (95% CI) by the Mantel-Haenszel method.

MAIN RESULTS

Only two trials involving 230 women met the inclusion criteria. Both studies had a moderate risk of bias. Oral cabergoline, 0.5 mg daily, was given as an intervention and compared with a matched placebo. A statistically significant reduction in OHSS was observed in the cabergoline treated group (OR 0.40, 95% CI 0.20 to 0.77; 2 RCTs, 230 women) with a number needed to treat (NTT) of 7. There was a statistically significant difference in the incidence of moderate OHSS, favouring cabergoline (OR 0.38, 95% CI 0.19 to 0.78; 2 RCTs, 230 women) but not in severe OHSS (OR 0.77, 95% CI 0.24 to 2.45; 2 RCTs, 230 women). There was no significant difference in the clinical pregnancy rate (OR 0.94, 95% CI 0.56 to 1.59; 2 RCTs, 230 women), miscarriage rate (OR 0.31, 95% CI 0.03 to 3.07; 1 RCT, 163 women) or any other adverse effects of the treatment (OR 2.07, 95% CI 0.56 to 7.70; 1 RCT, 67 women). However, no data on multiple pregnancy rate or live birth rate were reported in either trial.

AUTHORS' CONCLUSIONS

Cabergoline appears to reduce the risk of OHSS in high-risk women, especially for moderate OHSS. The use of cabergoline does not affect the pregnancy outcome (clinical pregnancy rate, miscarriage rate), nor is there an increased risk of adverse events. Further research should consider the risk of administering cabergoline and the comparison between cabergoline and established treatments (such as intravenous albumin and coasting). Large, well-designed and well-executed RCTs that involve more clinical endpoints are necessary to further evaluate the role of cabergoline in OHSS prevention.