In vitro fertilisation (IVF) is a multi-step fertility treatment designed to help individuals or couples conceive when natural conception is difficult. The process typically spans several weeks and involves carefully timed medications, monitoring, laboratory fertilisation, and embryo transfer.
IVF cycle monitoring is a crucial phase in assisted reproduction, involving regular, often daily, transvaginal ultrasounds and blood tests to track how the ovaries respond to stimulation medications. This process typically lasts 10-14 days and allows specialists to monitor follicle growth, measure the uterine lining, and determine the optimal timing for egg retrieval while avoiding complications like Ovarian Hyperstimulation Syndrome (OHSS).
Transvaginal Ultrasounds (Scans)
Monitoring usually begins with a “baseline” scan on day 2 or 3 of the menstrual cycle.
Purpose: To count follicles (fluid-filled sacs containing eggs) and measure their diameter in millimetres.
Endometrial Lining: The ultrasound also checks the thickness and quality of the uterine lining (endometrium), which is vital for embryo implantation.
Frequency: Usually, 4-5 scans are performed over a two-week period, with increased frequency toward the end of the cycle.
Blood Tests (Hormone Panels)
Blood is tested, typically in the morning, to check for rising hormone levels that indicate maturity.
Oestradiol (E2): This hormone is produced by developing follicles. As follicles mature, oestradiol levels rise, helping predict egg maturity and the risk of OHSS.
Progesterone (P4): Monitored to ensure it stays low during stimulation. A premature rise can indicate premature ovulation, which may lead to a “freeze-all” cycle where no fresh transfer occurs.
Luteinizing Hormone (LH): Monitored to ensure premature ovulation does not occur.
Ovarian Stimulation (8-12 Days)
The ovaries are stimulated to produce multiple eggs rather than the single egg released in a natural cycle. Hormonal medications are used to stimulate egg production. Patients undergo frequent monitoring using blood tests and ultrasounds. Monitoring tracks follicle growth and hormone levels to ensure safe and optimal egg development.
What Happens Next: The “Trigger” and Retrieval
Monitoring continues until 2-3 leading follicles reach an average diameter of 17-22 mm.
The Trigger Shot: Once the follicles are mature, the clinical team will instruct you to take a “trigger injection” (hCG or GnRH agonist) at a precise time, usually 34-36 hours before the egg collection.
Egg Retrieval (Collection): A minor, sedated surgical procedure where a specialist uses an ultrasound-guided needle to aspirate (remove) the fluid and eggs from the follicles. The procedure usually takes 20–30 minutes. Most patients resume normal activity within a day.
Collected eggs are immediately transferred to the IVF laboratory.
Fertilisation in the Laboratory: Once eggs are retrieved, fertilisation occurs in the lab.
There are two fertilisation methods:
- Conventional IVF: Eggs are combined with thousands of sperm, and fertilisation occurs naturally.
- ICSI (Intracytoplasmic Sperm Injection): A single sperm is injected directly into the egg, often used in male-factor infertility.
After fertilisation, embryos begin developing under controlled lab conditions.
Embryo Development (5-7 days)
Embryos are cultured and monitored for several days. During this stage, embryologists observe cell division and growth. The strongest embryos reach the blastocyst stage (day 5–7). Viable embryos may be frozen for future use. This stage helps identify the embryo most likely to result in pregnancy.
Post-Monitoring Phase: Transfer and Testing
Following retrieval, the next steps depend on the agreed treatment plan:
Fresh Embryo Transfer: If a fresh transfer is planned, a single embryo is transferred into the uterus 3-5 days after retrieval.
Freeze-All/FET: If progesterone is too high or the lining is not optimal, all suitable embryos are frozen (cryopreserved) for a Frozen Embryo Transfer (FET) in a subsequent cycle.
During the monitoring phase, your team may adjust medication doses based on results, which are generally communicated by a nurse.
Embryo Transfer
Embryo transfer is a simple, minimally invasive procedure. A thin catheter places the embryo into the uterus. No anaesthesia is typically required as the procedure is usually quick and painless. Often, only one embryo is transferred to reduce the risk of multiple foetuses. If the uterus needs preparation, transfer may occur in a later frozen cycle.
Frozen Embryo Transfers (FET)
Extra embryos can be cryopreserved for future cycles. This avoids repeating ovarian stimulation and retrieval, provides additional chances for pregnancy, and often results in high success rates.
Luteal Phase Support
After the transfer hormone medications (usually progesterone) support implantation. Patients continue normal daily activities but avoid intense exertion. Emotional support is important during the waiting period.
Pregnancy Test (The “Two-Week Wait”)
About 9–14 days after embryo transfer, a blood test (beta-hCG) is done to check if the embryo has implanted. If positive, early ultrasounds confirm implantation and foetal heartbeat. If unsuccessful, the fertility team reviews results and plans next steps.
How Long Does the IVF Process Take
Ovarian stimulation is done over a 2-week period. Egg retrieval to embryo transfer may take another 1 week, and pregnancy is tested 2 weeks after that. Overall, a cycle takes about 4 to 6 weeks, or longer if embryos are frozen and transferred later.
Key Takeaways
IVF is a carefully controlled, step-by-step process. Each stage, from stimulation to embryo transfer, is designed to maximise pregnancy success. Multiple cycles may be needed. Frozen embryos provide additional future opportunities without repeating the full process.
Read through this article by CCRM Fertility to learn more about the IVF cycle.
