What is IVF?

IVF ( In Vitro Fertilization ) is a Medically Assisted Reproduction ( MAP ) technique that aims to provide pregnancy to an infertile woman or couple. It involves a set of processes and methods used over approximately 2 to 3 weeks, culminating in transferring at least one embryo to the uterus.

IVF’s name comes from the fact that the union of gametes ( egg and sperm ) takes place in a laboratory. Given its greater complexity, it is usually classified as a second-line technique. Intrauterine insemination (IUI) is a first-line ART technique.

IVF in Pakistan has been used in Pakistan for over 40 years, beginning in 1976, when the first child born using this technique was reported. This innovative method quickly became common practice around the world, with an estimated 7 million pregnancies having been achieved using IVF. 1-3% of pregnancies in Pakistan are achieved using variants of this technique, which has truly revolutionized human reproduction.

ICSI (Intracytoplasmic Sperm Injection) is a variant of IVF, limited to the oocyte fertilization technique.

What does the IVF technique consist of?

In short, after a specialist in Reproductive Medicine has studied the woman or couple, and this technique has been proposed as the most appropriate in their context, there are three distinct phases :

1. Ovarian stimulation;
2. Gamete collection and fertilization in the laboratory;
3. Embryo(s) transfer.

The technique has variants (e.g., ICSI), but the sequence of events is similar for the woman or couple. The medication used may vary according to the clinical situation.

How is the procedure performed?

1. Ovarian stimulation

Egg collection can only be carried out when adequately developed follicles are in the ovary. Although these can be collected from a woman during her spontaneous cycle, in human menstrual cycles, only one follicle with a mature oocyte usually develops per cycle. As the probability of success of the technique also depends on the number of oocytes obtained, hormone stimulation is generally carried out to get a greater number of oocytes.

Ovarian stimulation has several variations, but regardless of the type, frequency, duration, and timing of starting the medication (usually subcutaneous injections), the aim is supraphysiological follicular development. This means we trigger greater development of follicles (each with its oocyte) and prevent them from being released before the ideal time.

Usually, the woman is given hormones to stimulate the ovaries and simultaneously prevent spontaneous ovulation.

The medication is adjusted, and the ideal time for oocyte retrieval is determined through regular ultrasound monitoring and, possibly, blood tests. When indicated, new medication triggers the oocytes’ final development (maturation), and their retrieval is scheduled.

This phase will be the longest of the entire IVF cycle. It usually takes between 8 and 12 days from the start of the injectable medication.

1. Follicular puncture and in vitro fertilization

On the scheduled day of ovulation (approximately 34 to 36 hours after the appropriate medication), the oocytes and sperm are collected.

The oocytes are collected in the operating room, under ultrasound control, through the vagina. This procedure can be performed under local anesthesia but is usually performed under sedation (while the patient is asleep). The follicle aspiration usually lasts only a few minutes (between 5 and 15). The number of eggs retrieved depends on the number of follicles aspirated and their development during the stimulation phase.

Sperm collection is usually done by masturbation. Depending on the case and the reason for infertility, another source of sperm may be necessary (e.g., testicular biopsy), but these are specific situations.

The gametes (sperm and eggs) are then processed in the laboratory by an embryologist, who will carry out the fertilization process. The sperm will enter the oocyte spontaneously or in a manipulated manner (in the case of ICSI, in which it is injected into the oocyte using a microscope).

1. Embryo development and embryo transfer

Fertilization of the oocytes is verified a few hours after these processes. The number of embryos depends on the previously collected eggs (oocytes).

Embryos are evaluated morphologically to determine the likelihood of normal development in utero.

Embryo transfer is usually carried out between days 2 and 5 of development. The quality of the embryos is systematically assessed during this period.

A single embryo or more (usually no more than two) can be selected for transfer from among the embryos with adequate development for their stage. Implantation always occurs after the 6th day of development, so a late transfer (5 days) may allow for a better selection of embryos without compromising the results.

Surplus (leftover) well-developed embryos may be cryopreserved (frozen), allowing them to be transferred later. In some situations, to protect the woman from complications (e.g., ovarian hyperstimulation) and/or improve the results of the icsi treatment Pakistan for another reason, all the embryos may be cryopreserved. In other words, in this case, no embryo transfer will be performed after the puncture, and all good-quality embryos will be cryopreserved for transfer later (in another menstrual cycle). The ideal timing for this transfer of frozen embryos depends on the reason for the cryopreservation, but it may be in the cycle (month) following the treatment.