In Vitro Fertilization

Many ART procedures involve in vitro fertilization, the process in which eggs, retrieved from the ovary, are fertilized in the laboratory with the partner’s sperm (or donor sperm, if necessary). Subsequently, the resulting embryos are transferred into the woman’s uterus.  There are four major steps in an IVF cycle:

1. Follicular stimulation and monitoring
A physician prescribes medications or hormones in order to increase the likelihood of collecting multiple eggs and to control the timing of your cycle. You and your partner may administer these medications on a daily basis within the privacy of your home. The clinic staff then monitors your progress by evaluating the number of ovarian follicles in development through vaginal ultrasonography and serial blood samples taken at the clinic. A follicle is a sac of fluid in the ovary which may contain an egg (oocyte). A physician determines the number and frequency of these tests.

Just prior to the retrieval of eggs, a patient takes an additional injectable medication to complete the maturation of the eggs. The retrieval is scheduled only if there is an adequate number of follicles ready.

2. Oocyte (Egg) Retrieval
Each egg retrieval takes place under  intravenous conscious sedation in the clinic.The physician inserts a needle through the vagina under ultrasound guidance into the ovaries to aspirate (withdraw) follicular fluid from each follicule. It is important to understand that not all follicles contain eggs. Following the retrieval, the patient rests in the recovery room to allow effects of the anesthesia to subside.

3. Fertilization and Incubation
Once the eggs have been retrieved, the male partner’s sperm is collected for a clinic embryologist to mix with the eggs in the laboratory.  An embryologist may choose from a number of techniques, including a microinsemination technique called intracytoplasmic sperm injection, also known as ICSI (“ik-see”). In ICSI, an embryologist injects a single sperm directly into an egg under a microscope with a tiny needle. The lab staff then incubates the fertilized eggs (embryos) for two to five days prior to transfer.

4. Embryo Transfer Procedure
If the embryos have developed normally after incubation, a physician transfers a predetermined number of embryos through the cervix into the uterus via a small catheter (hollow tube). The patient and her physician determines the number of embryos for transfer based on individual circumstances such as age and medical history. No anesthetic is required for this painless procedure, although valium is given for uterine relaxation.

In order to enhance the likelihood of conception, the physician prescribes hormonal therapy following the transfer. As in the natural reproduction process, a pregnancy may or may not result. If any excess embryos exist after the transfer, the patient may request evaluation for possible freezing and use for a subsequent treatment cycle. 

Variations on the IVF Procedure

Embryos that are not transferred but continue to develop in the laboratory can be cryopreserved (frozen). Embryos may be frozen anytime after the fertilization stage (pronuclear zygotes) which is one day after egg retrieval up to and including the blastocyst stage which is 5 days after retrieval. Most commonly, embryos are frozen at either day three or day five. Your physician will discuss with you both options and a decision will be reached as to which is best suited for your particular case. The lab staff store these embryos in liquid nitrogen for possible thawing later.

While pregnancy rates with frozen embryos are not quite as high as with fresh embryos, the success rates are still quite respectable and the preparation for a frozen embryo transfer is much simpler and less expensive compared with a fresh cycle attempt. Freezing only embryos that survive to the blastocyst stage maximizes the chance for success in a thaw cycle.

This is a procedure for surgically transferring a sperm-egg mixture into the fallopian tubes for fertilization. As in IVF, anesthesia is required for this procedure and the patient rests afterward in the recovery room. This procedure is rarely performed nowadays due to the increased risks of general anesthesia, surgical laparoscopy and overall complexity compared with standard IVF.

This information is provided for general education purposes and is not intended to take the place of a discussion with your physician. If you have questions about any aspect of your health, you are advised to speak with your physician.