Investigation and Clinical Approach of Recurrent Implantation Failure

Recurrent implantation failure (RIF) derives from the practice of IVF. The ability to identify implantation failure after the transfer of embryos raised the possibility that there exists a patho-physiological state leading to repeated implantation failure. RIF can be defined as the repeated lack of implantation after the transfer of embryos. Prior to IVF, treatment resulted either in a pregnancy or not. IVF added the ability to further compartmentalize the treatment process so that it became possible to know when an embryo was transferred and if an implantation occurred. Hence RIF became a possible clinically identifiable phenomenon. The relevance of defining such a problem lies in the ability to diagnose patho-physiological conditions, which might be amenable to treatment and thus increase the implantation rate thereby increasing a couple’s chance of conception.

Many practical procedural problems exist when trying to define implantation failure. One limitation when defining implantation and implantation failure is that at present, implantation can only be determined by a rising quantitative hCG level which occurs a number of days after implantation has actually occurred or failed. There remains a time-frame which cannot be further compartmentalized and thus limits the ability to precisely define the cause of implantation failure. Thus, for practical purposes, implantation is defined as a rise in the quantitative hGC level determined at some point after embryo transfer. The most accurate way to determine this would be to do daily serum HCG levels starting after embryo transfer. But again practicality dictates that the first level is drawn at some point after embryo transfer and for many programs this is usually 10–14 days after hCG is given.

The timing of when the first hCG determination is performed will affect the implantation rate. The earlier the first hCG determination is done, the lower the failed implantation rate will be since some pregnancy losses will occur prior to the hCG determination for those programs measuring it later in the cycle. Any definition of RIF requires a standardization of the time from embryo transfer to the time used to determine a positive hCG level. The definition also needs to establish what will be considered a pregnancy when using hCG. For example, will any value above the threshold value be considered evidence of implantation or will there need to be rising hCG levels? Finally, the day of embryo transfer needs to be established. For example, suppose there was a preventable cause of failed implantation that occurred at the morula stage. Programs transferring day three embryos would have a higher failed implantation rate than those programs transferring blastocyst embryos.

The accuracy of a clinical definition is to a large extent determined by the simplicity or, conversely the complexity, of the problem. A physiologic process that has a single factor is easy to define in its entirety. A pathological process that alters the physiology of the process in question may be caused by a single factor and, if measurable, the definition of the disease process is simple and accurate. The thesis of this manuscript has two prongs. First, implantation is extremely complex and highly redundant. Continuation of the species is evolutionarily a high priority. Therefore, the evolutionary process has preserved the ability to implant through accruing a number of individual processes, many of which are, in and of themselves, not necessary, but collectively contribute to a maximum chance for implantation. Second, because of the complexity and redundancy of implantation, assigning etiologies for implantation failure and RIF will be difficult.

There are some processes involved in implantation which are simple and absolutely required for implantation to occur. But there are many processes which are not necessary but contribute to implantation. Therefore, the problem with implantation failure as well as RIF is not in defining the problem, which is self-evident, but in assigning causality to the phenomenon. Some causes of IF and RIF will be a single factor. Their identification and their contribution will be easier to discern. However, implantation failure and RIF may be a result of a threshold phenomenon whereby there are a multitude of factors required for maximum implantation efficiency. A failure of any one of these factors might, or might not, reduce the overall implantation rate. But to reach a state whereby implantation failures, or implantation fails repeatedly, might require errors in a number of factors and might not be the same factors for each case of IF or RIF. The identification of this problem becomes complex and very difficult to approach experimentally.

Any deviation from or interruption of the normal structure or function of any part, organ, or system, or combination thereof, of the body that is manifested by a characteristic set of symptoms or signs, and whose etiology, pathology, and prognosis maybe known or unknown. Implantation failure and especially to recurrent implantation failure demonstrates just how difficult it becomes to define a disease. There are two ways of approaching a definition for a normal implantation rate: evaluate spontaneous pregnancy rates in fertile couples, or evaluate implantation rates when using donor oocytes. There are many factors intervening when couples have intercourse which could result in a less than perfect system so that more than 50% of the cycles do not result in a pregnancy. Therefore, using the natural pregnancy rate in maximally fertile women does not provide the best definition of a normal implantation rate.

IVF provides a more definable system since it involves oocyte, sperm and, endometrium. For this more defined system, the relevant statistic is not normal implantation rate but rather, the maximum implantation rate. Any deviation from this maximum implantation rate would represent a compromise that is, by definition, a disease. Identifying the maximum implantation rate requires evaluating implantation rates obtained through the use of normal oocytes, sperm, and endometrium when the IVF procedure is done by the technically most adept IVF units. This condition is frequently met for women using donor oocytes for age-related ovarian failure. The implantation rate for the double embryo transfer patients was equally high at 56%. It would appear that the maximum implantation rate for IVF is between 40% and 60%. For IVF programs with substantially lower implantation rates, the problem may be technical related to either the clinical or laboratory components of the program. Until a program’s implantation rates meet industry standards, evaluating the patient for problems with implantation failure will be premature.

Defining the term “recurrent” is very challenging, analogous to defining infertility or recurrent pregnancy loss. A problem when using pregnancy rates based upon number of transfer cycles relates to the variability of the number of embryos transferred on any given cycle, the quality of the embryos transferred, and the day of embryo transfer. Defining recurrent implantation failure as three unsuccessful IVF attempts actually defines RIF in terms of failed IVF cycles and does not address the issue of implantation rates. Some patients may have a large number of poor quality embryos transferred for a given IVF cycle; whereas, others may have only one or two embryos transferred. Thus, defining RIF in terms of pregnancy rate does not allow an evaluation of the implantation rates. Also, the day of transfer greatly impacts the pregnancy rate since blastocyst embryos have a higher implantation rate than day three embryos.

Therefore, time to pregnancy should be shorter for cycles with blastocyst transfers and especially if many blastocysts are transferred on a given cycle. For example, transferring three blastocyst embryos should result in a pregnancy sooner than transferring only a single blastocyst embryo. The definition of RIF would be fewer transfer cycles for multiple optimal embryos transferred per cycle than for either poorer quality embryos, high quality embryos transferred on day three, or fewer blastocyst embryos per cycle. Age also has an impact on the pregnancy rate and is a known factor for implantation failure. Thus, defining recurrent differs depending upon the age of the population studied. Finally, the choice of the number “three” deserves some attention. For three to be the operational number of IVF cycles, there needs to be some correlation with that number and the incidence of implantation failure. For example, the cycle fecundity needs to decline after three cycles of IVF if RIF is defined by the number of cycles for transfer. Where there is no implantation failure, the cycle fecundity rate remains constant. The cycle fecundity rates of 36.2% for each of the first four cycles of donor oocyte embryo transfers.

However, cumulative pregnancy rates for IVF have demonstrated a decline in cycle fecundity with successive failed IVF cycles. A clinical pregnancy rate of 19.0% for the first IVF cycle, 17.4 for the second, 11.8 for the third, 10.8 for the fourth, and less than 6% for the next three successive cycles of IVF. Defining RIF after three cycles of IVF with this data is problematic given the fact that is seems the number should be either two or four cycles of IVF. Furthermore, notes an even more dramatic decline in pregnancy rates with successive IVF cycles where the embryos transferred were blastocyst embryos. The cycle fecundity rates were 36% for the first transfer, 19% for the second, and 9% for the third. Given this data, RIF may need to be defined as failed two or even one cycle of transfers with blastocyst embryos.

A second method of defining RIF uses the number of embryos transferred. All consecutive pregnancies from a large IVF program were analyzed to determine the total number of embryos that had been transferred to achieve each pregnancy. The number to achieve 80% of the pregnancies was 8 and for 95% of the pregnancies it was 12. Arbitrarily defining normal at the 95 percentile, RIF was defined as having failed to achieve a viable pregnancy if more than 12 embryos had been transferred. The patients participating in this study were all infertility patients and, thus, the pregnancy rates were not maximal as they might have been had donor oocyte recipient patients been used. The pregnancy rates and implantation rates were below what they are today, and these pregnancies were achieved using day three transfers, not blastocyst transfers. Therefore, the number used to define RIF would be lower today and depend upon whether day three or blastocyst transfers were being considered.

Any definition of RIF will be found wanting given the complexity and redundancy of the implantation process. However, a working definition of RIF can be based upon the number of embryos transferred. The definition will depend upon the stage of embryo development. The actual number will vary by center and can best be calculated by using pregnancies delivered in patients using donor oocytes. The definition of RIF used in our program requires the transfer of =8, 8-cell stage embryos or =5 blastocyst embryos. Evidence of implantation is accepted when there is a rise in hCG for hCG measurements made 12 and 14 days after the hCG injection that is given to trigger the time of retrieval.

Implantation Bleeding after Embryo Transfer

Embryo transfer is the most critical step in the IVF procedure. You can have the best quality embryos, but if they are not placed into the uterus correctly, then pregnancy will not occur. That is why transfer technique is so important. Pregnancy rates can vary by Physicians, and this is all because of transfer technique. Once the disparities between transfer techniques were corrected and integrated, the pregnancy rates became consistent. For this reason, you want to seek out a Physician who has a lot of experience with embryos transfers and comparable good pregnancy rates. So, if you were paying much more money for an IVF cycle, would ask for a more experienced doctor to do the transfer.

After we discharge our patients from implantation unit, we send them home with instructions to go about the rest of the day and ensuing two weeks with normal, reduced activity. There is no need to be on bed rest. All our patients have different medication protocols that they go home with. Often referred to as the two week wait so we have now come to the end of the IVF procedure and the maximum that our technology can help a person to achieve a pregnancy. We are at the point where we have to wait and see. If a day-3 transfer was done, it will take approximately 7 days for the remainder of the process to be completed and for the pregnancy test to be positive. For that reason, it is refer to pregnancy tests at 8 or 9 days post transfer. For a blastocyst transfer, you only need three more days to get a positive pregnancy test.

Pregnancy occurs when the egg is released by the ovaries, fertilized by sperm to form a Zygote fertilized eggs. This process occurs in the fallopian tubes, the Zygote travels to the uterus and during this period, it was further divided to form a blastocyst, which can be described as a ball of cells with sheath. Once the blastocyst reaches the uterus, it gets out from the protective outer layer and glued on the inside lining of the uterus (endometrium). Through this entanglement, blastocyst formed a relationship with the mother's blood vessels, to receive the oxygen and nutrients needed for growth.The blastocyst can cause a slight amount of bleeding, such as penetrating the endometrium and will be attached to the uterus. This blood coming out from the uterus through the vagina, and this incident is called implantation bleeding, which is considered as one of the signs of early pregnancy. Although it is a sign of pregnancy, absence does not mean that there is no pregnancy, no. In other words, every pregnant woman is not likely to experience bleeding, because it is not necessary to cause bleeding while the blastocyst implanting itself in the uterine wall. It is said that only a third of women experience this condition. The basic idea about the signs and symptoms of implantation bleeding and the time of the occurrence may be useful in recognizing the condition.

This usually happens right before the estimated date of the menses. The average menstrual date is calculated as the 14 day from the date of ovulation (the cycle can vary between women) and the implantation bleeding occurs between six to twelve days after ovulation. In other words, this bleeding usually occurs on the third or fourth week of the date of the last menstrual period. Eggs that have been fertilized or Zygote takes approximately five to six days to travel from the fallopian tubes toward the uterus. After that, it will be attached to the endometrium. Thus, implantation bleeding is said to occur in nine to twelve days of ovulation. But in some cases, it may occur as early as six days as well. So, the time frame for the occurrence of implantation bleeding is usually given as 6 to 12 days after ovulation. Even the time taken by the blood to come out of the womb may affect the time of implantation bleeding.

As mentioned above, this type of bleeding is caused by small amounts of blood that is released from the blastocyst attachment locations on the endometrium. First of all, you must understand that implantation bleeding is not likely to occur in women. It may happen that the endometrium does not bleed at all, while the blastocyst will be attached. Even the amount of bleeding can vary from one woman to another. So, the first and foremost sign of bleeding implantation bleed itself. The vaginal discharge may be too minimal or spotty in some women, whereas in some others may be a little heavier. However, in this case the type of bleeding, blood will be pink or Brown, like old blood (it takes some time for the blood to come out of the womb). Commonly, implantation bleeding is not associated with any symptoms, but some women may experience minor cramps in uterus and increased basal body temperature (the lowest temperature attained by the body during rest, usually while a sleep).In addition to the implantation bleeding and other symptoms of pregnancy include nausea or vomiting, tender and swollen breasts, frequent urination, fatigue, flatulence and increased sensitivity to odors. If these symptoms develop after implantation bleeding along with the late period; they may indicate pregnancy. However, confirmation of the pregnancy is done with a blood test and urine as well as obstetrical ultrasound. If implantation bleeding is accompanied by pain, you should consult with your obstetrician.

Blood contaminates the endometrial cavity at the time of the transfer, this will kill the embryos and pregnancy will not occur. The catheter must be placed as gently and a traumatically as possible. That is an absolute requirement. The endometrium, which is now in its fullest growth state, thickened from estrogen stimulation, can be easily scraped and these cause bleeding. You should not worry if brown blood or discharge occurs at the time of transfer, it will usually manifest within the first day or so after the transfer, but not into the mid-Luteal phase or later. That type of bleeding would be from a different source. There are situations, however, when bleeding can occur but not be ominous. Sometimes a woman's cervix will bleed easily from being scraped by the speculum or irrigation or wiping. This external bleeding will not affect the endometrial cavity as long as the transfer catheter is not exposed to the blood. For example, I do not let the catheter get exposed until the introducer is well into the cervical canal, near the internal cervical, to begin advancing the catheter. Bleeding that occurs later in the luteal phase, days after the transfer, is very common if vaginal progesterone is used. 

For some patients, because used both vaginal and injectable progesterone by the experts, it is almost 90%, but the bleeding tends to occur near the time of the pregnancy test or soon thereafter. This is probably caused by some erosion occurring on the external cervix. The exact cause, however, is not clearly understood. It is usually light spotting and can be anywhere from red to brown. Red is newer blood and brown is old blood. Patients not to worry about this; the only bleeding that patient would worry about is bleeding that is red and heavy like a period. This is not good, and should not occur if the hormones progesterone and/or estrogen have not been discontinued. Some patients will experience slight spotting 3-5 days after embryo transfer and refer to this as "implantation bleeding." Whether or not this is caused by implantation is not known. Implantation should not cause bleeding. However, again, if it is not bright red blood that is heavy like a period, it should not cause worry.

The body is a fluid and dynamic structure and there will be many sensations that patients report during this period. Some will report many types of “pains”, some will have “cramping” and some will have “bleeding”. Most of these symptoms are not of any consequence but cause patients to needlessly worry. Some doctors have referred to these “pains or cramping” as implantation related. That may be the case but no one knows for sure. Certainly with implantation, the uterus is undergoing changes and cramping tends to be one way that uteri react. So, if the timing is appropriate, namely at the point where implantation would be expected as described above, then these sensations could certainly be related to it. Of course, onset of one’s period can also be signed by cramping but this is usually accompanied by bleeding. If adequate hormone replacement is given in the luteal phase of the process, then the period should not start until the medications are stopped. That is the cause of the onset of the bleeding and cramping associated with a period; it is the withdrawal or abrupt drop in hormone levels. Some will claim that this is the uterus “stretching or growing” but this could not be the case at this point in the pregnancy. 

The embryo is like a mere fleck of dust within the cavity and not big enough for the uterus to begin “growing.”Some patients will experience sharp or stabbing pains, on the other hand, that may not be from implantation but more from the ovaries. About three days after the retrieval, the ovaries will refill with fluid and this stretching of the follicles and ovaries certainly can cause pain in one side or both sides. This is the pain sensation that most patients have during this period of time. Post IVF complications causing severe pain include Ovarian Hyper stimulation Syndrome (OHSS), ovarian torsion (twisting), ovarian flow of blood, Ectopic pregnancy and Pelvic infection. 

If the pain is mild, then intervention is probably not required but if severe, it could be one of these serious medical problems that will require medical treatment because they could be life threatening. You should know, however, that these complications are very rare. On the other hand, if you have had a positive pregnancy test and these symptoms occur impending miscarriage could be another source of cramping or pain.Bleeding within this period of time is also a very common complaint. In most cases this bleeding is inconsequential but it could also indicate problems such as inadequate hormone support for the Luteal phase, thereby causing the endometrial lining to start to slough. 

It could also indicate that the period is starting or that an abnormal pregnancy exists or is being miscarried. When the bleeding is light, I usually will reassure my patients that no intervention is required. For one, there is no intervention that can be done, other than checking hormone levels and increasing the progesterone if the level is inadequate. Secondly, this could be normal, if in fact it is implantation bleeding. Thirdly, if vaginal progesterone is used, the progesterone may be causing the cervix to be more delicate or friable and therefore cause cervical bleeding. If implantation bleeding is accompanied by pain or heavy bleeding, you should consult with your obstetrician.