What is the IVF (In Vitro Fertilization) procedure?

In Vitro Fertilization (IVF) Procedure

In vitro fertilization (IVF) is a multistage assisted reproductive technology procedure where oocytes are retrieved, fertilized outside the body, and the resulting embryos are cultured in a laboratory environment before being transferred to the uterus to achieve pregnancy. 1

Overview of the IVF Process

IVF involves several sequential steps, each critical to the overall success of the treatment:

1. Ovarian Stimulation

   • Controlled ovarian stimulation using medications such as gonadotropins, clomiphene citrate, or aromatase inhibitors to produce multiple follicles 2, 3
   • Regular monitoring via ultrasound and blood tests to assess follicular development
   • Aim is typically for two dominant follicles to maximize success while minimizing multiple pregnancy risks 2

2. Oocyte Retrieval

   • Performed when follicles reach appropriate size (>18mm) 4
   • Transvaginal ultrasound-guided procedure under sedation
   • Timing coordinated with hCG trigger shot to optimize oocyte maturity

3. Sperm Collection and Preparation

   • Fresh semen sample provided on day of retrieval
   • Sperm washing and preparation techniques to isolate motile sperm with normal morphology 2
   • For male factor infertility, specialized techniques may be employed

4. Fertilization

   • Conventional IVF: Oocytes and prepared sperm are incubated together
   • ICSI (Intracytoplasmic Sperm Injection): Single sperm directly injected into each mature oocyte; indicated for severe male factor infertility 5

5. Embryo Culture

   • Fertilized eggs (zygotes) are cultured in specialized media
   • Embryo development is monitored for 3-5 days
   • Quality assessment based on morphology and development rate

6. Embryo Transfer

   • Selected embryos transferred into the uterine cavity using a thin catheter
   • Typically performed 3-5 days after fertilization
   • Number of embryos transferred depends on quality, patient age, and clinical factors
   • Remaining viable embryos may be cryopreserved for future use

7. Luteal Phase Support

   • Progesterone supplementation to support implantation and early pregnancy
   • Continued until pregnancy is established

Success Rates and Factors Affecting Outcomes

Success rates for IVF vary significantly based on several factors:

• Female age: Most significant predictor of success, with declining rates after age 35 6
• Cause of infertility: Tubal factor, male factor, unexplained infertility, and endometriosis have different prognoses 3, 6
• Duration of infertility: Longer duration associated with poorer outcomes at every stage 6
• Previous pregnancy history: Prior successful pregnancy improves prognosis 6

The live birth rate per initiated IVF cycle is approximately 37%, though this varies by age and diagnosis 5.

Special Considerations

Fertility Preservation

• IVF with embryo or oocyte cryopreservation is an established method for fertility preservation 2
• Particularly important for patients facing gonadotoxic treatments (e.g., cancer therapy) 2
• Options include:
  • Embryo cryopreservation (requires partner or donor sperm)
  • Oocyte cryopreservation (no longer considered investigational) 2
  • Ovarian tissue cryopreservation (emerging option, especially for prepubertal patients) 2

Modified Protocols

• Natural cycle IVF (without ovarian stimulation) may be appropriate in selected cases, with pregnancy rates of approximately 22.5% per cycle 4
• Minimal stimulation protocols may reduce medication costs and side effects

Potential Complications

• Multiple pregnancy (risk reduced with single embryo transfer)
• Ovarian hyperstimulation syndrome (1-5% of cycles) 3
• Procedural risks including bleeding, infection, or damage to surrounding structures

When to Consider IVF

IVF is typically indicated for:

• Bilateral tubal factor infertility
• Severe male factor infertility
• Failed less invasive treatments
• Advanced maternal age (>38-40 years) 5
• Unexplained infertility after failed other treatments 3

Important Considerations for Patient Counseling

• Realistic expectations: Success rates decline with age and vary by diagnosis
• Financial implications: Multiple cycles may be needed
• Psychological impact: Emotional support throughout the process is essential
• Alternative options: Including donor gametes, surrogacy, or adoption if appropriate

IVF has evolved significantly since its introduction in 1978, with continuous improvements in laboratory techniques and clinical protocols that have enhanced success rates while reducing complications 1, 7.