by CRA Barcelona



In vitro fertilization or IVF is a technique based on rescuing the largest number or eggs produced by the ovaries in each cycle, to later join them with the male’s sperm optimized in the laboratory, thus obtaining embryos. Subsequently, the development of the embryos produced is strictly controlled, selecting the best to be transferred into the uterus of the mother-to-be, thus achieving the desired pregnancy.

In vitro fertilization consists of 4 phases: ovarian stimulation, ovarian puncture, fertilization of the eggs and embryo transfer.


Ovarian stimulation

In normal conditions of all the eggs that begin to develop in each cycle in the ovaries, only one will ovulate. In the cycles of in vitro fertilization by a hormone treatment, it is possible to stimulate the growth of the ovules available in that cycle.

When menstruation arrives, a visit to our center is scheduled to perform a basal ultrasound. If the ultrasound is correct, ovarian stimulation is started with drugs containing follicle-stimulating hormone (FSH). This hormone is administered subcutaneously and the physician indicates the dose in an individualized manner depending on each patient’s characteristics. Afterwards, the controls are performed with a specific periodicity for each case, adjusting the dose to the response observed. This process lasts approximately from 8 to 12 days.

Ovarian Puncture

It consists in the retrieval of oocytes from the ovarian follicles, produced with the stimulation, by puncture with an adapted needle. It is performed under anesthetic sedation and with transvaginal ultrasound guidance. The ovarian follicles are located and then, with an aspiration system, the follicular fluid is collected where the oocytes are to be stored in test tubes with culture media. These tubes are immediately handed over to the the biologists for them to be identified and the oocytes are isolated.

The puncture is an outpatient procedure, it does not require general anesthesia or hospital admission; it last 15-30 minutes, and 1 to 2 hours later the patient is discharged, recommending bed rest for the rest of the day. The number of oocytes retrieved per cycle is highly variable depending on each woman, but in general it ranges from 6 to 12 per puncture. It can be fewer in patients with low ovarian reserve.

The sperm should be obtained shortly after the ovarian puncture, with a period of prior sexual abstinence of 3 to 5 days. In our laboratory, the sperm sample is processed to optimize its fertilizing capacity.

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fertilization of the ovules

There are two methods of fertilization of the ovules:

  1. Conventional in vitro insemination or IVF
    The insemination of the ovules is performed with some 100.000 mobile spermatozoa for each one. The ovules and the sperm are kept together in the incubator until the following day, when it is determined if fertilization has occurred.
  1. Intracytoplasmic Sperm Injection or ICSI
    Intracytoplasmic microinjection of sperm is the introduction, by a microinjector, of a sperm in the cytoplasm of the ovule.

The rate of fertilization by conventional IVF or ICSI is approximately 70-80%. On the day following the puncture (referred to as day +1), the center will get in touch with you to let you know how many ovules have been fertilized.

From that moment on, the embryo begins to divide. Embryo transfer is performed 2 to 5 days after the puncture.

Embryo culture

The embryos obtained are placed in incubators that maintain the conditions necessary for their development. In our center we have state-of-the-art incubator technology, which allows not only optimal conditions at all times for each and every one of the embryos, but also continual control of the development of these embryos, impoving the selection of those with the best chances of producing a healthy child.

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Embryo transfer

Embryo transfer is performed 2 to 5 days after the puncture. Our team of embryologists selects the embryos with the best quality to be transferred. Two or three embryos are usually transferred; the rest may be frozen to be used in later cycles, improving the probability of pregnancy per each cycle started.

The embryo transfer process is performed in the operating room, without the use of anesthesia, and you can go home on that same day. You should start a treatment with progesterone to improve the process of embryo implantation,  and two weeks after the transfer you will have a control with us to confirm the pregnancy by a blood test and subsequently an ultrasound.

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