IVF is a protocol-oriented process, which is carried out in a series of steps in a definite order. Embryo implantation is one of the key aspects of IVF and the fate of the cycle depends greatly upon its success. There are times when women have picture-perfect embryos, yet they fail to implant in the uterus and this results in failure of the IVF cycle.
Confusing as it may be for the patient, she may also be depressed by the situation and blame herself for not being able to sustain the embryo. There are several cases when IVF cycles fail one after the other because of the simple, plain reason that the embryos fail to implant. It becomes essential to identify the exact cause so that the specialist can address the condition and find a way out for the couple.
Identifying the Culprit
Before trying to learn more about the possible reasons of implantation failure, it is essential to understand what it actually is. IVF involves lab culture of the embryo by combining the egg and the sperm in a petri dish. Once the prepared embryo(s) reaches a three day or five day (blastocyst) stage, it is transferred in the woman’s uterus, where it is meant to implant for a pregnancy to take place.
Implantation is a miracle of nature, which can be compared to a seed germinating in the soil. The embryo is like the seed while the uterus replicates the soil. Whether the embryo is natural or cultured, it has to set up communication with the endometrial tissue in the uterus in order to get implanted therein and grow into a pregnancy. Every embryo is not meant to be implanted and some are doomed to get rejected for one reason or the other. It is necessary for the specialist to identify the reason for the same, so that chances of success can be improved the next time around.
When a woman comes across recurrent implantation failure (which is verified from the fact that the otherwise healthy looking embryos fail to implant in repeated attempts), she loses her confidence and considers several strange reasons to be responsible. For instance, she may believe that the embryo might have actually fallen out of the uterus after the transfer or that there is some defect in her uterus. However, scientific logic says otherwise. It identifies three possible reasons for implantation failure:
- Poor quality of the embryos
- Lack of uterine receptivity
- General health complications
Implantation Failure: The Embryo Quality
The genetic condition of the embryo has a far-reaching influence over the chances of its implantation. This is the very reason why young women get pregnant faster than those with advanced maternal age, as the latter are prone to produce embryos with genetic defects. Such embryos are genetically incompetent and they are not actually meant to implant and grow into a pregnancy (because nature plays its role here). Even if implantation does take place, the risk of an early miscarriage is high. These cases make an irrefutable proof in themselves that embryo quality needs to be good for successful implantation.
Implantation Failure: Endometrial Receptivity
Another factor that plays a crucial role in embryo implantation is the receptivity of the uterus, specifically the endometrial tissue which lines it. Endometrial receptivity is gauged in terms of “window of implantation”, the period when the uterus is able to receive the embryo (blastocyst). Normally, this period falls between day 20-24 of the menstrual cycle, while the embryo transfer is done on day 3 or day 5 after the ovulation (when the eggs are extracted). Embryo transfer is timed in such a manner that these two can coincide with each other.
Ultrasound scans can be used to assess the endometrial receptivity; the test is used to measure the thickness of the endometrium, which needs to exceed 8 mm. Similarly, progesterone exposure is essential for the endometrium to become receptive. Implantation failure may happen if there is problem with any of these factors, such as the endometrial lining being too thin or premature increase in the level of progesterone during the IVF cycle. Similarly, receptivity may be impaired due to presence of infection, fibroids or adhesions in the uterus.
Implantation Failure: Other Causes
While embryo quality and uterine receptivity are the main causes of implantation failure, it can be attributed to some other factors too. For instance, the women who have had a traumatic embryo transfer are less likely to achieve implantation. This is usually seen in cases when conditions like cervical stenosis make it hard to access the uterus via the cervix. Techniques such as ZIFT are considered for the embryo transfer so that the chances of implantation are maximized.
Dealing with Implantation Failure
Recurring implantation failure can be depressing and can break the morale of the couple but the good news is that it can be managed successfully with the right approach. Older women are recommended to make use of donor eggs for IVF so that the success rate is improved for them. The same applies to those who have poor ovarian reserve because of advanced age or some other reason. Similarly, careful monitoring of the progesterone levels during the IVF cycle can be of help for those who are combating problems related to uterine receptivity. For women with infections, fibroids or adhesions in the uterus, these conditions need to be treated effectively before making an IVF attempt. Assisted hatching is an advanced therapy which is being used to improve the chances in recurrent IVF failure cases. This technique involves making a hole in the zona pellucida (outer membrane) of the embryo so that it can “hatch” and harbor itself in the uterus.
Besides these treatment techniques, patients may also consider switching their IVF clinics if they come across recurrent implantation failure because the root may lie in the incompetence of the IVF Centre. Change in IVF protocol may do the trick and so can use of frozen embryo transfer. In cases, when nothing seems to work, couples may need to consider IVF.
Gaudium IVF is a trusted name for providing advanced infertility treatments for tackling the most complicated and hopeless cases. Visit Gaudium IVF for a free second opinion of the acclaimed fertility specialist, Dr Manika Khanna.