In vitro fertilisation

• Ovarian Stimulation

  Under normal physiological conditions, a structure called a follicle grows in the ovary each month, containing an egg. During ovulation, the ovary releases this egg, which is picked up by the fallopian tube, where it may be fertilized by a sperm.

  To increase the chances of success with IVF, it is necessary to obtain several mature, high-quality eggs. For this reason, a controlled ovarian stimulation is carried out with hormonal treatment (gonadotropins) lasting between 9-12 days to stimulate multiple follicle growth.

  The gynecologist determines the most appropriate stimulation protocol for each patient. During this time, strict monitoring is done, including ultrasounds and hormonal tests, to assess follicle growth and quantity.

  Once ovarian stimulation is deemed successful, an HCG injection is administered to complete egg maturation. Egg retrieval is scheduled 36–38 hours later.

• Egg Retrieval and Identification

  Egg retrieval is done by aspirating the follicular fluid. Following stimulation and HCG administration, most eggs mature and are released into the follicular fluid.

  Although performed in an operating room under sedation, egg retrieval is a simple and painless procedure that doesn't require hospitalization. It takes about 15–20 minutes, and the patient can go home a few hours later.

  The doctor uses a vaginal ultrasound probe to access the ovaries. The fluid is sent to the embryology lab, where the eggs are identified and placed in culture dishes until fertilization.

  Not all follicles contain eggs, and not all retrieved eggs are viable. Therefore, the number of visible follicles doesn't necessarily match the number or quality of eggs retrieved.

• Sperm Sample Preparation

  At the same time as egg retrieval, a sperm sample is prepared in the lab. It can be from the partner or a donor, depending on the case. If it's from the partner, he must bring the sample, following WHO guidelines for 2–7 days of sexual abstinence. Donor samples are pre-frozen and ready in our sperm bank.

  Regardless of the origin, the sample is processed to isolate the highest-quality, most motile sperm and separate them from seminal plasma, immotile sperm, and other cells.

  Several sperm preparation techniques exist, and the most suitable one is chosen based on the sample. The goal is to select the best sperm and induce the physiological changes needed (capacitation) to allow fertilization.

  If sperm cannot be recovered from the ejaculate, a testicular biopsy is needed to isolate them directly from the tissue.

• Egg Insemination

  Eggs are inseminated a few hours later using the most suitable technique:

  In Vitro Fertilization

  Mature eggs are placed with sperm so fertilization can occur naturally. This is used when the semen quality is good. Between 40,000 and 80,000 sperm are used per egg.

  Intracytoplasmic Sperm Injection (ICSI)

  One sperm is injected directly into the egg using micromanipulation techniques. The eggs must first be stripped of surrounding cells. This is done under 400x magnification.

  Specific Techniques

  Intracytoplasmic Morphologically Selected Sperm Injection (IMSI)

  IMSI is an advanced version of ICSI where sperm are selected in real-time using a high-magnification microscope (around 6,000x).

  Specific Techniques
• Fertilization Assessment

  Between 16 and 20 hours after insemination, fertilized eggs (zygotes) are identified and evaluated. The presence of two pronuclei (one female and one male) confirms correct fertilization. These contain parental genetic material and are visible for only a few hours.

  Eggs that failed to fertilize or fertilized abnormally are discarded at this point.

• Embryo Culture
  

  The embryos are cultured in an incubator for 2–6 days depending on the case.

  During this time, embryologists monitor embryo development to select those with the best implantation potential for transfer or freezing.

  Assessment criteria include general morphology, cell quality, division speed, and kinetics, following scientific guidelines.

• Culture Conditions

  Eggs and embryos are cultured in special plates that suspend and protect them. These are kept in an incubator with ideal temperature, humidity, air quality, and atmosphere for fertilization and embryonic development.

  Maintaining strict control of these environmental conditions is vital, both in the incubator and lab, as they affect embryo viability.

  The goal is to mimic the natural environment of the fallopian tubes and uterus as closely as possible.

• Embryo Transfer

  Embryo transfer involves placing embryos into the uterine cavity. It usually occurs 2–3 days after egg retrieval, though it may be done on day 6 in some cases.

  The embryos with the best implantation potential are selected. The number transferred depends on each case and the embryos' evolution. Current Spanish law (Law 14/2006) allows a maximum of 3 embryos per transfer cycle.

  The transfer is performed using a special catheter and guided by ultrasound. It’s a simple, painless procedure done in a room next to the lab. The patient can return home shortly after but is advised to rest for a few days.

  A pregnancy test (blood test) can be done 12–13 days after transfer to confirm pregnancy.

• Embryo Freezing (Cryopreservation)

  High-quality embryos not transferred in the current cycle are frozen for use in future cycles, avoiding the need for further stimulation and retrieval.

  These embryos are kept cryopreserved until the couple decides to use them.

  They are safely stored in the GIROFIV Embryo Bank.

This is a much simpler treatment, allowing the transfer of embryos generated in a previous IVF cycle and cryopreserved. Before the transfer, the patient undergoes a mild hormonal treatment to prepare the uterus. Embryos are thawed a few hours before transfer. It's important to note that not all embryos survive the freezing and thawing process, although survival rates have improved significantly thanks to advancements in cryopreservation. GIROFIV uses vitrification as the preferred embryo freezing method.