We need to be a little careful with the linguistics here because even the stimulation of the ovaries during the IVF cycle is sometimes still labeled as COH or controlled ovarian hyperstimulation – meaning that normally in the cycle there’s just one follicle growing here, we’re actually supporting all the antral follicles recruited for this cycle and we’re motivating them to grow. Whenever, there’s a larger number, then let’s say 15, some set this threshold at 18, some at 20 follicles of a certain size then, it’s are usually felt as a pressure in the belly, the ovaries grow larger – usually they’re about the size of a plum, during the stimulation they can grow to the size of an orange or grapefruit even so, that can bring certain pressure and discomfort. Still during the stimulation itself there is minimal or no risk of the hyperstimulation, the problem or this the syndrome usually only ensues after the so-called maturation trigger shot is distributed. This used to be just the hcg hormone (either pregnyl or ovidrel) which actually supports the ripening of the eggs very successfully, it has a positive effect on the endometrium (on the receptivity on the endometrium) but it has a rather long biological half-life and in those cases where there was a larger number of follicles (more than 18, more than 20) and then this shot was actually after its distribution working slowly through time period of six or seven days, this was the situation where the hyperstimulation eventually started to bother the patient. Fortunately in the past five, six, seven days there is an alternative to that. It came actually with a new cryopreservation method where now the embryos if we perform the so-called “freeze all” – meaning we freeze all the embryos and perform the transfer later. Now, the current cryopreservation methods are so gentle that the embryos can withstand the cryopreservation very well and without any lowering of their success rates. Thanks to that, we don’t need to focus on the endometrium and the triggering of the egg maturation is performed with a different injection which stops its effect after approximately 12 to 24 hours and no hyperstimulation ensues. So currently, we are talking about the so-called hyper-stimulation free clinic because we have alternatives which successfully help us avoid this problem and this should be now a problem of the past.
Ovarian hyperstimulation is a condition that’s caused by exposure to Human Chorionic Gonadotropin (hCG). It can come in two different formats, the first is whereby you’ve been exposed to the trigger to cause that final maturation so that hCG causes early OHSS or if you should be coming pregnant, then the pregnancy itself is producing hCG that’s what we detect on a pregnancy test. Then that further compounds it until you get a revolving cycle and that causes late OHSS. In terms of talking of how OHSS manifests itself, it can be kind of increasing severity from just having kind of slightly swollen ovaries, having fluid within your tummy, having fluid within your chest and having some breathing difficulties. There’s a whole kind of standard or scale of that. At present, we’ve now got ways of trying to prevent moderate or severe OHSS very successfully. Fortunately that’s a very rare complication – less than one percent of cycles in the UK now have OHSS.
OHSS or ovarian hyperstimulation syndrome is a condition in which the ovaries have an excessive response to the treatment, to the gonadotropin we gave to our patients during the IVF protocols. This is a condition more commonly found in PCOS patients, polycystic ovary patients or very young women that have a high ovarian reserve. We start with the protocol and begin checking how fast and how big the ovary becomes in size and the size of the follicles. If the response to the protocol is too large, we change the trigger and we don’t transfer the embryo. By doing this we can assure at almost one hundred percent that we will not have ovarian hyperstimulation syndrome. Of course the protocol of IVF generates hyperstimulation but the syndrome is different and it can be uncomfortable for patients. Some time ago before the techniques to avoid it, we did not admit patients due to this syndrome. The good news is that nowadays we have ways to prevent it and even if they are young, PCOS or high response, we know how to avoid this syndrome and help prevent the patient from experiencing this condition.
Ovarian hyper-stimulation syndrome is the only side effect of assisted reproduction treatments and consists of the ovaries having an extreme response to the medication as well as growing and producing discomfort such as fluid retention feeling swollen e.t.c. Nevertheless, any woman under controlled ovarian stimulation might suffer hyper-stimulation syndrome, even if there is a spontaneous conception. But the risk increases dramatically with the high number of and large number of ovarian follicles because the granulose cell secretes not only estradiol but also the basic substance responsible for the ovarian hyper-stimulation syndrome.
Ovarian hyperstimulation syndrome is a very rare condition, a very rare syndrome that eventually can occur in the in vitro fertilization process after using injections to stimulate your ovaries. There is a very early ovarian hyperstimulation syndrome that occurs because of specific medication use during the trigger shot or it could be late is ovarian hyperstimulation syndrome that can occur because you get pregnant.
There are some risks that maximize the chances of is ovarian hyperstimulation syndrome, for instance, if you are very thin, if you are using high doses of medication, and if you have more than 15 follicles growing during the stimulation and estradiol more than 3,000.
If we have these two last pieces of information, that you have a high response, it is very important not to transfer the embryos in the same month, freeze all the embryos after Gonal shot, and once you recover and you don’t have any symptoms, we will do the transfer the next month.
What are the symptoms of ovarian hyperstimulation syndrome? You start to have severe pain in your abdominal area, you start to have increased liquid intake, and, eventually, you can have coagulation disorder and difficulties breathing. So, it is a very rare condition but it is important to avoid it because, with all the medication and the new techniques we have in reproductive treatments, it should be 0%. It should be that we have zero patients with ovarian hyperstimulation syndrome.
