Controlled Ovarian Hyperstimulation (COH)

Controlled Ovarian Hyperstimulation (also known as superovulation) is a highly effective fertility treatment which uses injectable medications to induce the production of multiple ovarian follicles, thereby increasing the chances of pregnancy. COH is used in conjunction intrauterine insemination (IUI).

When is it used?
COH is considered a second line therapy. It is a very effective fertility treatment for mild to moderate male factor and unexplained infertility. Recent studies have shown that COH and IUI is more effective than other forms of IUI.

It is not used when the female has blocked fallopian tubes or for females over the age of 40.

What to Expect:
The aim of COH is to have the woman produce between 2-4 eggs and to control the time of ovulation. Birth control pill may be used, and a baseline ultrasound performed before the start of the cycle.

If COH is indicated, you will be taught to self administer subcutaneous injections to promote the development of one or more follicles in the ovary. Follicle growth is monitored by ultrasound scans. A detailed schedule will be made by the nurses taking into account your schedule and a calendar will be provided detailing further appointments.
Patients will start to take an injectable medication known as gonadotropins (follicle stimulating hormone) early in their cycle. Common injectable gonadotropins used in a COH cycle may include: Puregon, Gonal-F and Menopur.

A trigger injection of HCG is administered when the follicle(s) are ready. IUI is timed as between 24 and 36 hours later.

As with any procedure there is always a risk of infection or bleeding. However, the two main complications related to COH are Ovarian Hyperstimulation Syndrome (OHSS) and Multiple Birth.

OHSS is a potentially life-threatening complication of fertility treatment associated with injectable hormones (gonadotrophins). The exact cause of OHSS is unknown although increased leakiness of the blood vessels is thought to be responsible. The severity of OHSS varies from mild to severe. While it is common to experience mild symptoms of abdominal bloating and moderate weight gain, severe cases may be associated with accumulation of fluid in the abdomen, vomiting, diarrhea and shortness of breath. Fortunately, the incidence of severe OHSS is less than 5 %. The treatment used to reduce this complication is careful follicle tracking. Should your physician be concerned about the development of OHSS, your cycle may be cancelled, and/or other medications may be prescribed.

Multiple Birth – is a serious complication of any fertility treatment. Following COH treatment should there be more than 4 follicles ready at the time of ovulation trigger, you will be given a choice of cycle cancellation, follicle reduction, or conversion to IVF in order to limit the potentially dangerous consequence of multiple pregnancy.

Success rates:
The success rate of COH is dependent upon several factors, including a woman’s age, her ovarian reserve, and the reason for her infertility. When used appropriately the following success rates can be achieved.

15%-20% for women age 30 and under
15% for women between the ages of 30-35
10-15% for women ages 35-39
5%-10% for women aged 40.

It may not be a suitable treatment for women over the age of 40.