Appy · 6 min
IVF walk-through, what actually happens, stage by stage
8 sections · 6 min read
What happens at the initial assessment before IVF starts?
Every pathway begins with a thorough assessment. Expect: evaluation (, , antral count), uterine assessment via transvaginal ultrasound, sperm analysis (count, motility, morphology), and general health screening (thyroid, vitamin D, rubella immunity, infectious disease).
UK research suggests the IVF outcome gap for South Asian women shows up in fresh cycles, not frozen ones, a difference worth knowing before protocol choice is made.
Your results inform the choice of stimulation protocol. Each protocol has trade-offs; the right one for you depends on your , age, and previous cycle response.
Egg collection
Eggs retrieved under sedation about 36 hours after the trigger injection.
Fertilisation in the lab
Eggs meet sperm (IVF) or sperm injected directly (ICSI). Embryos grown to day 3 or day 5 (blastocyst).
Fork, fresh transfer route
If lining and hormone levels look right, an embryo is transferred 3–5 days after egg collection. Whole cycle ends here.
Fork, freeze-all route
All viable embryos are frozen. The body is allowed to recover from stimulation before any transfer happens.
Frozen embryo transfer (FET)
In a later cycle (natural or medicated), the lining is prepared and a thawed embryo transferred. Lower OHSS risk and, in many groups, comparable or higher live-birth rates.
What are the three main IVF stimulation protocols?
Long Protocol (GnRH Agonist): suppresses the natural cycle for about two weeks before stimulation begins. Controlled hormonal environment with precise timing. Typically suitable for women with regular cycles and normal . Longer overall timeline.
Antagonist (Short) Protocol: stimulation begins immediately. A GnRH antagonist is added mid-stimulation to prevent premature . Often recommended for women with lower reserve, poor responders, or women over 35. Fewer injection days. May reduce OHSS risk.
Mild Stimulation Protocol: lower doses. Aims to produce fewer eggs but potentially of higher quality. Reduced side-effects and cost. Minimises OHSS risk. Suitable for certain patient groups including older women and poor responders.
What does IVF monitoring involve and what is the trigger injection?
Stimulation typically lasts 8–14 days. You self-administer injections. The clinic monitors you with regular transvaginal ultrasound (counting and measuring follicles) and blood tests (oestradiol levels) to guide medication adjustments.
When follicles reach 18–22 mm, a trigger injection initiates final egg maturation. Two types: hCG (mimics natural ), or GnRH agonist (for patients at higher OHSS risk). Timing is critical, it must be administered at the exact time the clinic specifies.
What happens during egg collection in IVF?
Performed approximately 36 hours after the trigger. Under sedation or light anaesthesia. Ultrasound-guided aspiration through the vaginal wall into each . Typically 20–30 minutes; recovery a few hours. May cause mild cramping and spotting.
Each 's fluid is examined by embryologists to identify eggs, which are then prepared for fertilisation.
What is the difference between IVF and ICSI fertilisation?
Conventional : eggs and prepared sperm are placed together in culture medium, allowing natural fertilisation. Used when sperm parameters are normal.
(intracytoplasmic sperm injection): a single sperm is injected directly into each mature egg. Used for male-factor infertility, previous fertilisation failure, or when sperm numbers are very low.
Day 1: two pronuclei visible. Days 2–3: 2–8 cell cleavage. Days 5–6: blastocyst stage (the goal). Embryologists grade embryos based on appearance and development rate.
Why do embryo numbers drop at each IVF stage, and is that failure?
attrition is the natural reduction in viable embryos at each stage. Even with a strong egg collection, only a small proportion may reach blastocyst. This reflects the natural inefficiency of human reproduction, most fertilised eggs do not develop to even in unassisted conception.
Attrition at each stage is normal and expected, not indicative of treatment failure. Clinics that prepare you for this upfront are doing you a service.
Should you choose a fresh or frozen embryo transfer?
Fresh transfer: in the same cycle as egg collection. Frozen transfer: embryos cryopreserved and transferred in a subsequent cycle. Current evidence increasingly supports frozen transfer, which allows the body to recover from the stimulation phase before the uterus receives an embryo (Shrestha et al 2015; Wei D et al 2019).
Quick check
Has your clinic discussed freeze-all options with you?
For your doctor
I would like to discuss whether a freeze-all (segmented) approach is appropriate in my cycle. Specifically, I would value review of OHSS risk markers (AMH, antral follicle count, peak oestradiol), endometrial appearance at trigger, and the clinic's published live-birth rates for fresh vs frozen transfer in patients with my profile (age, AMH band, ethnicity where relevant).
What this is for: making the freeze-all conversation specific. Freeze-all isn't a 'better' or 'worse' route in the abstract, it's a clinical decision keyed to your numbers. This snippet asks the team to share the numbers and rates that drive the decision in your case.
For your doctor
I would value a structured conversation about the IVF pathway options available to me, protocol type, fresh vs frozen, PGT, including expected timelines, monitoring schedule, and where the evidence is strongest for someone in my profile. I would like the same information regardless of whether the cycle is funded or self-funded so I can plan around it.
What this is for: setting the conversation up so the same clinical detail is shared with you no matter which route you're on. The medicine is the medicine; you should get the full picture.
Frozen is usually preferred when: OHSS risk is high (common in PMOS and South Asian women), oestradiol is very high at the end of stimulation, the womb lining is not ready, genetic testing (PGT) is planned, or you are unwell.
Fresh may still be offered when: OHSS risk is low, a good embryo is ready at day 3 or 5, lining looks normal, no PGT planned.
What questions are worth asking your IVF clinic at each stage?
• What is my OHSS risk? • What was my peak oestradiol level? • How thick is my womb lining, and has it tripled in appearance? • What are your clinic's live birth rates for fresh vs frozen in women like me? • Is PGT being considered? • What happens to embryos we don't use?
A good clinic answers all of these clearly. If answers feel rushed, ask for them in writing.
How did this land with you?
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Reviewed by clinicians
Authored and reviewed by clinicians from the founding team. Information only, not personalised medical advice.