Polycystic ovary syndrome (PCOS) is a common hormonal system disorder among women affecting between 5% and 10% of women of reproductive age worldwide. Women with PCOS may have enlarged ovaries that contain multiple small collections of fluid (subcapsular microcysts) that are arranged like a “string of pearls” immediately below the ovarian surface (capsule), interspersed by an overgrowth of ovarian connective tissue (stroma). The condition is characterized by abnormal ovarian function (irregular or absent periods, abnormal or absent ovulation and infertility, androgenicity (increased body hair or hirsutism, acne) and increased body weight – body mass index or BMI. Women with PCOS are at increased risk that ovarian stimulation with gonadotropins will result in the, of development of severe ovarian hyperstimulation syndrome (OHSS), a life-endangering condition that is often accompanied by a profound reduction in egg quality. Such eggs will upon fertilization often yield an inordinately high percentage of “incompetent” embryos which have a reduced potential to propagate viable pregnancies. Concern and even fear that their PCOS patients will develop of OHSS often leads the treating RE to take measures aimed at reducing these risks. In this regard, it is my opinion that the most important consideration is the selection and proper implementation of an individualized or customized   ovarian stimulation protocol. What follows is a critical assessment of methods to prevent OHSS and/or limit its severity:

1. PROLONGED COASTING…my preferred approach: My preferred approach is to use a long pituitary down-regulation protocol coming off the BCP which during the last 3 days is overlapped with the agonist, Lupron/Buserelin/Superfact. The BCP is intended to lower LH and thereby reduce stromal activation (hyperthecosis) in the hope of controlling LH-induced ovarian androgen (predominantly, testosterone) production and release. I then stimulate my PCOS patients using a low dosage of recombinant FSH-(FSHr) such as Follistim/Gonal-F/Puregon. On the 3^rd day of such stimulation a smidgeon of LH/hCG (Luveris/Menopur) is added. Thereupon, starting on day 7 of ovarian stimulation, I perform serial blood estradiol (E2) and ultrasound follicle assessments, watching for the number and size of the follicles and the blood estradiol concentration [E2]. I keep stimulating (regardless of the [E2] until 50% of all follicles reach 14mm. At this point, provided the [E2] reaches at least >2,500pg/ml, I stop the agonist as well as gonadotropin stimulation and track the blood E2 concentration daily. The [E2] will almost invariably increase for a few days. I closely monitor the [E2] as it rises, plateaus and then begins to decline. As soon as the [E2] drops below 2500pg/ml (and not before then), I administer a “trigger” shot of 10,000U Profasi/ Novarel/Pregnyl or 500mcg Ovidrel/Ovitrel. This is followed by an egg retrieval, performed 36 hours later. Fertilization is accomplished using intracytoplasmic sperm injection (ICSI) because “coasted” eggs usually have little or no cumulus oophoris enveloping them and eggs without a cumulus will not readily fertilize naturally. Moreover, they also tend to have a “hardened” envelopment (zona pellucida), making spontaneous fertilization problematic in many cases.  All fertilized eggs are cultured to the blastocyst stage  (up to day 5- 6 days) and thereupon are either vitrified and preserved for subsequent transfer in later hormone replacement cycles or (up to 2) blastocysts are transferred to the uterus, transvaginally under transabdominal ultrasound guidance. The success of this approach depends on precise timing of the initiation and conclusion of “prolonged coasting”. If started too early, follicle growth will arrest and the cycle will be lost. If commenced too late, too many follicles will be post-mature/cystic (>22mm) and as such will usually harbor abnormal or dysmature eggs.  Use of “Coasting” almost always prevents the development of severe OHSS, optimizes egg/embryo quality and avoids unnecessary cycle cancellation. If correctly implemented, the worst you will encounter is moderate OHSS and this too is relatively uncommon.
2. MULTIPLE FOLLICLE ASPIRATION: In some cases, in spite of best effort, you inadvertently find mean follicle size to exceed 16mm, thereby leaving too little time to implement “coasting”. On other occasions, “coasting” fails to effectively lower the [E2} below 2,500pg/ml within 3 days. In such case the number of developing follicles can effectively and drastically reduced (culled) through selective transvaginal aspiration prior to initiating the “trigger” with 10,000U hCG. This will almost invariably be accompanied by a rapid and significant drop in the plasma estradiol concentration along with a drastic reduction in the risk of OHSS occurring without significantly compromising egg/embryo quality. Upon completing surgical follicular reduction, the surviving follicles can be allowed to continue their full development, at which point the hCG “trigger” can be implemented. The drawback associated with this approach is that it unfortunately interjects an additional surgical intervention into an already complex and stressful situation.
3. EMBRYO FREEZING AND DEFERMENT OF EMBRYO TRANSFEDR (ET): OHSS is always a self-limiting condition. In the absence of continued exposure to hCG, symptoms and signs as well as the risk of severe complications will ultimately abate. Thus, in the absence of pregnancy, all symptoms, signs and risks associated with OHSS will disappear within about 10-14 days of the hCG trigger. Conversely, since early pregnancy is always accompanied by a rapid and progressive rise in hCG , the severity of OHSS will increase until about the 9^th or tenth gestational week whereupon a transition from ovarian to placental hormonal dominance occurs, the severity of OHSS rapidly diminishes and the patient will be out of risk. Accordingly, in cases where in spite of best effort to prevent OHSS, the woman develops symptoms and signs of progressive overstimulation prior to planned ET, all the blastocysts should be vitrified and cryostored for FET in a subsequent hormone replacement cycle. In this way women with OHSS can be spared the risk of the condition spiraling out of control.
4. TRIGGERING WITH LOW DOISAGE hCG; Because of the fact that hCG augments the development of OHSS, many RE’s prefer to use a reduced dosage of hCG for the “trigger. This is either done by administering 5,000U (half the traditional dosage) or by administering, a 250mcg (rather than 500mcg) of DNA recombinant form of hCGr (Ovidrel/Ovitrel) in the hope that by doing so the risk of critical OHSS developing will be lowered. While this indeed might be true, it is my opinion, that the reduced dosage is usually insufficient to optimize the efficiency of egg meiosis, especially when there are so many follicles present. Thus, while the use of a reduced "trigger" dosage of hCG might well reduce the risk and occurrence of OHSS-related life-endangering complications, the price to be paid is reduced egg quality/"competency".
5. “TRIGGERING” WITH A GnRH AGONIST (E.G. “LUPRON/BUSERELIN): More recently, an increasing number of RE’s are triggering egg maturation by way of injecting an agonist (Lupron/Buserelin/Superfact)  to initiate the patient’s own pituitary gland to release a large amount of LH.  The idea is to mimic what happens in natural cycles to promote egg maturation (meiosis) and ovulation, namely to have the agonist cause a "surge" in the release of body's own pituitary LH to trigger egg meiosis (maturation). But the amount of LH released in by the pituitary gland is often insufficient to optimize meiotic egg maturation and thus, while this approach also lowers the risk of OHSS it again comes at the expense of egg quality/competency.

A word of caution: I do not use long term administration of antagonists (Ganirelix/Cetrotide/Orgalutron), such as with the agonist/antagonist conversion protocol (A/ACP) in high responders whom are at risk of developing OHSS prolonged in-cycle administration of  because it can interfere with the E2  assay (often causing the value to be understated), and serial measurement of E2 is a vital part of monitoring patients undergoing “coasting.”