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Many factors can prevent sperm and egg from joining spontaneously. Fortunately, assisted reproduction techniques such as IVF can help. IVF is a highly complex assisted reproduction method in which sperm and egg are brought together outside the woman's body. This takes place in a glass dish in the laboratory.

One or more fertilized eggs (embryos) are then transferred to the uterus for implantation and subsequent development. Remaining embryos can be frozen for later use. Initially, IVF was used to treat women with blocked, damaged or absent fallopian tubes. Today, IVF is used to treat many causes of infertility, including endometriosis, male factor infertility and unexplained infertility.

The basic steps of IVF cycles are ovarian stimulation, egg retrieval, fertilization, embryo culture and embryo transfer.

After assessment and diagnosis of the couple's infertility and the necessary tests have been requested, the first step of IVF is ovarian stimulation. This is generally managed at the specialist's office using medication that stimulates the growth and development of multiple follicles. The aim of ovarian stimulation is to develop as many follicles as possible, which in turn provide mature eggs: the starting material for laboratory work. The specialist determines the medication, dosage and number of stimulation days.

After several days of medication, the specialist periodically monitors ovulation using transvaginal ultrasound to determine the best time to retrieve the eggs based on their size and maturity. Once this has been determined, egg retrieval is scheduled as the second step of IVF.

Egg retrieval is performed through ultrasound-guided transvaginal aspiration. This is a minor surgical procedure carried out under intravenous sedation in an equipped operating room. A vaginal transducer is inserted to identify the follicles, followed by a needle attached to the transducer to puncture and aspirate the eggs. This needle is connected to a suction system that collects the eggs in a test tube for subsequent laboratory analysis. The procedure generally takes 20 to 30 minutes. Once retrieval is complete, the patient stays in a surgical recovery area for one to two hours before discharge with the relevant instructions.

This assisted reproduction technique involves exactly the same steps as conventional IVF. As its name suggests, a single motile sperm cell is injected into the egg. This technique is preferred in cases of low sperm count (oligozoospermia) or reduced sperm motility (asthenozoospermia). In general, this technique yields the same results as conventional IVF.

PGD (preimplantation genetic diagnosis) is performed to detect hereditary diseases before embryo transfer. In this procedure, one or two cells (blastomeres) are removed from the embryo and examined for a specific genetic disease. Embryos that are not affected by the disease are considered healthy and available for transfer.

This procedure requires special equipment and sophisticated training for the biologist. Some couples, particularly those who carry a genetic disease, benefit from this technique to reduce the chances of having an affected child. Although PGD substantially reduces the likelihood of conceiving an affected child, it does not eliminate the risk entirely, and the diagnosis must be confirmed through chorionic villus sampling or amniocentesis during the first trimester of pregnancy.

To better understand assisted reproduction and how it can help infertile couples, it is important to understand how natural or spontaneous conception occurs. For this to happen, the man must ejaculate semen, the fluid containing sperm, into the woman's vagina during the ovulation period. Ovulation is a very complex process under the hormonal control of the pituitary gland, located at the base of the brain.

This gland produces FSH, follicle-stimulating hormone. Ovarian follicles are small cysts within the ovary that contain an egg that is not yet mature and cannot be fertilized. As its name indicates, follicle-stimulating hormone causes follicles in the ovary to grow. As they grow, these follicles produce another hormone called estrogen. Once a follicle reaches a certain size (>20 mm), the pituitary gland releases a second hormone, LH, or luteinizing hormone. This hormone causes the previously stimulated and enlarged follicle to rupture and release the mature egg. When this happens, we say that the woman has ovulated.

After ovulation, the egg is picked up by one of the fallopian tubes and transported through it toward the uterine cavity. Fertilization takes place in the tube. Sperm previously deposited in the woman's vagina travel through the cervix and uterus until they reach the fallopian tube, where they meet and fertilize the egg. Once fertilized, the egg (embryo) is transported toward the uterus and implants five to six days after ovulation to continue developing.

The last step in IVF is embryo transfer. Embryo transfer takes place between two and five days after egg retrieval, depending on the quantity and quality of available embryos. The procedure is generally performed without anesthesia, although minimal sedation is needed in special cases. The specialist identifies the cervix using a vaginal speculum. Once identified, the vaginal and cervical canals are briefly cleaned. As much mucus as possible is removed from the opening of the cervix to prevent it from obstructing the catheter containing the embryos.

At the same time, the biologist removes the embryos from the incubator and carefully places them at the tip of a catheter with a drop of culture medium. A small air-filled syringe is attached to the other end of the catheter.

The catheter is handed to the physician, who carefully inserts it through the cervix toward the top of the uterus. Embryo transfers are usually ultrasound-guided. A second operator simultaneously performs an abdominal ultrasound to ensure that the catheter tip is positioned 1 to 2 cm below the uterine fundus. Once this is confirmed, the specialist deposits the embryos, which appear on the ultrasound screen as a sudden white spot. The catheter is removed and examined under a microscope to ensure the embryos have been deposited. The patient then rests for one hour in the recovery room.

A laboratory with a highly skilled team and sophisticated technology is fundamental to the success and quality of fertility treatments, and at CREASIS San Pedro we are confident that we have these facilities. Our team of biologists specializing in embryo and gamete handling, together with our advanced technological equipment, has helped bring happiness to many couples over the years.

We are extremely meticulous about laboratory cleanliness and maintenance. We strictly control the entry of personnel and materials, and all procedures are performed using sterile technique.

It is essential to isolate the laboratory from outside air. At CREASIS San Pedro, our air purification system filters the air and traps dust particles and other contaminants that can negatively affect pregnancy rates.

We hold a health license granted by COFEPRIS through the Secretaría de Salud (SSA), which authorizes and certifies the quality of all assisted reproduction procedures.