In this article:
The process is customised to suit your health, with hormones given in a specific way and closely monitored. Understanding COS can help ease your worries, boost your confidence, and make your treatment more positive.
Ovarian Stimulation: An Overview
Ovarian stimulation is a medically supervised procedure that aims to stimulate the ovaries to produce multiple mature eggs in a single cycle. Here is a quick, step-by-step summary of the entire process:- Initial consultation and evaluation: Blood (AMH, FSH, LH, estradiol, etc.) and transvaginal ultrasound are performed to assess ovarian reserve and readiness.
- Start of hormonal stimulation: Daily follicle-stimulating hormone (FSH) injections are given to develop multiple follicles.
- Close monitoring: Regular ultrasounds and serum hormone measurements are needed to track the number and size of developing follicles.
- Triggering the maturation of eggs: Once the follicle has reached its optimal size, a hormone injection is administered to induce the final maturation of the eggs.
- Egg retrieval: Eggs are retrieved through sedation about 34-36 hours after the trigger for fertilisation procedures such as IVF or ICSI.
H3: Controlled Ovarian Stimulation (COS)
Controlled ovarian stimulation is a crucial part of assisted reproductive technology, as it stimulates the development of multiple mature eggs in one menstrual cycle. This process allows for:- Greater flexibility in embryo selection
- Cryopreservation of excess embryos for future cycles
- Increased chances of successful pregnancies compared to natural cycles
Natural vs. stimulated cycles
- Natural cycle: In a natural menstrual cycle, only one dominant follicle matures and releases a single egg. While some IVF treatments may use natural cycles, their success rates are lower due to the limited number of eggs available.
- Stimulated cycle: In COS, multiple follicles are matured simultaneously with the help of hormonal medications, drastically increasing the likelihood of retrieving several high-quality eggs for fertilisation.
Key Drugs Used in COS
Gonadotropins (FSH, LH)
- FSH (Follicle Stimulating Hormone): Stimulates the growth and maturation of ovarian follicles.
- LH (Luteinising Hormone): Complements the final development of the follicle and hormone production.
GnRH agonists and antagonists
- GnRH Agonists: Gnrh Agonists initially result in a hormone surge before suppressing gonadotropin production (e.g., Lupron).
- GnRH Antagonists: Act instantaneously by suppressing hormone secretion without an initial surge (see, e.g., Cetrotide, Ganirelix), allowing more flexibility in dosage and timing.
HCG trigger shots
Common COS Protocols
Long protocol
Short protocol
- GnRH agonists are introduced together with stimulation drugs early in the cycle.
- Usually applied for older patients or those with poor ovarian response.
Antagonist protocol
Mild stimulation protocol
Step-by-Step Process of COS
Qualifying assessments
- Determine antral follicle count (AFC)
- Determine AMH, FSH, and estradiol levels.
- Exclude ovarian cysts and other deviations.
- The Ovarian Stimulation Phase
Follicular monitoring
- Number and size of follicles
- Rising estradiol (E2) levels
Triggering of ovulation
Factors Influencing Choice of Protocol
- Age: Younger patients tend to have an improved ovarian response, while those above the age of 35 may require adjustments to stimulation strategies to maximise egg yield and quality.
- Ovarian reserve (AMH Levels, Antral Follicle Count): One indication for high gonadotropin doses or a different stimulation strategy, such as a mild protocol, is a low or insufficient antral follicle count.
- Previous IVF response: Patients with poor response (few eggs retrieved) or hyper-response (overdeveloped follicles) may require further individualised COS plans based on their responses for an improved outcome.
Side Effects of COS
Slight symptoms (Bloating, Change of Mood):
Mild symptoms (Ovary enlargement, Discomfort):
Severe condition (Ovarian Hyperstimulation Syndrome) (OHSS):
Tips to Consider for Effective Monitoring
Regular monitoring
Monitoring during controlled ovarian stimulation (COS) is not optional; it is necessary. Close monitoring allows the timely detection of:- Ovarian hyperstimulation
- Potential risks for premature ovulation
- Hormonal imbalance
Adjusting medication dosages
FSH, LH, and GnRH modulator dosages are subject to frequent change during COS. These changes serve to:- Avoid overstimulation
- Optimise egg quality
- Synchronise follicular growth
Early detection of OHSS
Weight gain escalates rapidly, and severe bloating in the abdomen and nausea form symptoms of OHSS. Early therapy with dose reductions, "coasting" (suspending stimulation), or using a GnRH agonist trigger can perhaps minimise risks.When to Contact Your Fertility Specialist
It’s important to reach out to your fertility specialist as soon as possible if you experience any of the following:- Severe abdominal pain or swelling
- Rapid weight gain (>2 pounds/day)
- Shortness of breath
- Decreased urination
Controlled Ovarian Stimulation (COS) has significantly improved fertility treatment, offering hope to individuals and couples trying to conceive. It involves careful planning, hormone administration, and regular monitoring to enhance egg yield and embryo quality and increase the chances of pregnancy. By following the right protocol, adhering to medical advice, and understanding potential side effects, you can approach this part of your fertility journey with confidence.
FAQs on Controlled Ovarian Stimulation: Drugs, Protocols, and Side Effects
- How long does Controlled Ovarian Stimulation (COS) typically take from start to egg retrieval?
Controlled Ovarian Stimulation typically takes around 8 to 14 days. However, the total IVF cycle, including initial evaluations, medication initiation, stimulation, monitoring, and retrieval, typically spans approximately 3 to 4 weeks, depending on the individual's response. - What are the main risks associated with Controlled Ovarian Stimulation?
The primary risks include mild side effects like bloating and mood swings, as well as rare but serious complications like Ovarian Hyperstimulation Syndrome (OHSS). Regular monitoring and individualised protocols minimise these risks, making COS generally safe under expert care.
