Research to Reader: fertility science
Commencing a stimulation cycle is an exciting time because of the possibility that lies ahead. That said, it is also damn scary and invasive - especially the first time! No one wants to be giving themselves daily injections and having internal examinations every few days but these are the things we do in hope of making a baby. This post covers two very rare, but possible, treatment risks: Ovarian Hyperstimulation Syndrome (OHSS) and Ovarian Torsion.
Stimulating the growth of lots of eggs (oocytes) in your ovaries is not without risk, just as there are risks associated with the surgical retrieval of all of your little eggs (hopefully you grow lots of eggs in there!). A common stimulation protocol, or if you are undergoing ovulation induction, involves injections with follicle stimulating hormone (and just as the name sounds this is going to grow lots of follicles that will surround your eggs). Follicle stimulating hormone often has names like Gonal-F, Puregon, Follistim or Menopur. Leutenizing hormone may also be used. These are the injections you give yourself daily (usually in the abdomen) that start on day 1 of your period and usually last for 8-14 days.
Not surprisingly if you are trying to grow a lot of eggs your ovaries are going to get large. Undergoing a few cycles myself I can tell you that I felt as though I was carrying around two oranges internally!
Monitoring of your growing eggs takes place regularly with blood tests and scans and when everything is just right you will be told to give yourself a ‘trigger’ injection ~36 hours prior to egg retrieval (usually human chorionic gonadotropin - drug names include Novarel, Pregnyl, Profasi or Ovidrel). This trigger allows for final maturation of the growing eggs.
With any stimulation cycle there is a small risk of developing ovarian hyperstimulation syndrome (OHSS). OHSS describes abdominal bloating and discomfort that occurs 7-10 days following the trigger injection and can be classified as mild, moderate or severe. While there is not a lot of data on mild cases, the combined incidence of moderate or severe OHSS is reported as 3.1% to 8% (1). Women with polycystic ovarian syndrome (PCOS), high egg reserves (antral follicle count) or those that generate a large number of eggs in response to their stimulation protocol are at risk.
It is good to be aware of the symptoms of OHSS. These are in Table 1 below.
Table 1. Classification of OHSS
While OHSS is not common, even rarer is ovarian torsion. As your ovaries become larger than normal there may be a tendency for them to ‘flip’ or rotate on their supporting ligaments. This twisting of the ovary requires immediate medical attention as ovarian blood flow is reduced and could potentially lead to death of ovary tissue. If you have OHSS there is an increased risk of ovarian torsion. Ovarian torsion usually presents as sudden onset lower abdominal pain, nausea and vomiting. While these conditions are very rare, in any women undergoing stimulation of the ovaries, torsion should be suspected (and ruled out) with any abdominal pain (sharp localized right or left lower abdominal pain and tenderness) as consequences can include loss of an ovary.
1. Delvigne A, Rozenberg S. Epidemiology and prevention of ovarian hyperstimulation syndrome (OHSS): a review. Hum Reprod Update. 2002; 8: 559-77.