Originally, IVF was designed for the treatment of severe tubal disease. Infections, inflammations, endometriosis and other conditions may cause irreparable damage to the fallopian tubes. Since the fallopian tube is the only place in the female body where normal fertilization can occur, if both tubes become blocked, pregnancy becomes difficult or impossible. IVF allows for successful fertilization outside the fallopian tube, thus bypassing the problem area. Tubal disease remains one of the most common indications for IVF.

Our office gets frequent phone calls asking the best way to get pregnant following a tubal ligation. In the days prior to IVF, the only possibility for pregnancy after a tubal ligation was to go through a lengthy operation. This procedure, called a microscopic tubal reversal, takes several hours to perform, requires an inpatient hospital stay, has a relatively long recovery period and is rarely covered by insurance. Although there is still the occasional patient for whom tubal reversal may be the best choice, IVF is generally less expensive and can achieve higher pregnancy rates in patients whose tubes have been tied.

Another common indication for IVF is low sperm counts. Because IVF allows us to super concentrate sperm during fertilization, successful fertilization can occur even when a male partner has a low count. In recent years a process has been developed where a single sperm can be injected into an egg to cause fertilization, a procedure called intracytoplasmic sperm injection, commonly referred to as ICSI. ICSI enables fertilization in even the every lowest of sperm counts.

Infertility is said to be “unexplained” when all testing is normal, yet a couple is still not able to conceive a child. When unexplained infertility does not respond to traditional treatments (clomid or stronger fertility medications combined with artificial insemination) IVF can be an option. IVF may also be used in conjunction with pre-implantation genetic diagnosis, PGD, to determine the presence of certain genetic disorders in embryos. This allows for only the unaffected embryos to be transferred back to the mother.

Patients often ask why it is necessary to produced multiple eggs in an IVF cycle, when it “only takes one embryo to get pregnant”. With IVF there is a significant loss as we go through each step of the cycle. Let’s take a typical example: A good stimulation cycle may produce 20 eggs. Of these, 16 may be mature. Immature eggs are much more difficult to fertilize. So, out of the 20 eggs, with an average fertilization rate of about 75%, we may have only 12 eggs that are successfully fertilized.

Now we may be down to 12 cleaving (dividing) embryos. When these embryos are examined after 3 days of incubation, it is typical to see some excellent embryos, some average to good embryos and some not so good embryos.

So, our original 20 eggs may break down to something like this: 5 excellent embryos, average to good embryos and 3 not so good embryos. Our best pregnancy rates usually occur when we are able to transfer the excellent embryos, and it is necessary to transfer more than one embryo to maximize our pregnancy rates. Obviously, we like to have as many of the very best embryos as possible available for transfer. Finally, the more good embryos we have the more we will have available for freezing. You can see then, the more eggs we start with, the more good embryos we are likely to have available for transfer and freezing.

In the past, we transferred our embryos on day three. This caused two dilemmas: We could only transfer 2 or 3 embryos for fear of multiple pregnancies. But if we had 5 good embryos, which ones were really the best? Over the past few years, improved culture media and techniques have allowed us to successfully culture most embryos to day 5 – the blastocyst stage. At this stage, we have found it much easier to select the 2 very best embryos, thus continuing to improve our overall pregnancy rates while decreasing the number of multiple pregnancies.

Remember, this is only an example. Some cycles yield far less than 20 eggs, others more than 20. The number of mature eggs and the number of eggs fertilized can very tremendously from cycle to cycle. Further, there is no predicting how many of the embryos will be excellent and how many will be poor. In some cycles, nearly all the embryos are excellent, and in rare cases, all the embryos may be of poor quality.