The considerable emotional, physical and financial burden associated with infertility treatment in general and with IVF in specific, demand that factors known to affect outcome be identified and regulated prior to initiating treatment. Just as a successful garden needs a ”good” seed properly planted in fertile soil to produce healthy plants, successful embryo implantation requires a good seed (genetically “normal” embryo) and fertile soil (receptive uterine lining) to make a healthy baby. I have long used this “Seed/Soil Relationship” analogy to help clarify the critical nature of the interaction between embryo and endometrium in the successful propagation of pregnancy.There have in the last decade been numerous reports suggesting that certain drugs/supplements (e.g. GCSF) and endometrial receptivity testing/preparation might dramatically improve implantation. As yet, none of these have been proven to be effective. This article addresses the influence of the most relevant and important factors that are known to affect endometrial receptivity and discusses approaches to treatment:
- Endometrial thickness
In 1989, I first demonstrated that in both normal and “hormonally stimulated” cycles, preovulatory endometrial thickness as assessed by ultrasound examination, is partially predictive of embryo implantation (pregnancy) potential following IVF. Ideally the endometrium should measure at least 8.0mm in thickness, (but preferably >9mm). A “poor” endometrial lining is most commonly due to: 1) inflammation of the uterine lining (endometritis) that usually occurs as a result of endometritis (inflammation of the uterine lining that can follow a septic delivery, partial retention of the placenta following delivery, abortion or miscarriage, 2) severe adenomyosis (gross invasion of the uterine muscle by endometrial glandular tissue), 3) multiple fibroid tumors of the uterine wall) 4) prenatal exposure to the synthetic hormone, diethylstilbestrol (DES) and, 5) following >3, consecutive, back to back cycles of clomiphene citrate ovulation induction.Treatment with vaginal Sildenafil (Viagra):Hitherto, attempts to augment endometrial growth in women with poor endometrial linings by bolstering circulating estrogen blood levels (through the administration of increased doses of fertility drugs, aspirin administration and with supplementary estrogen therapy) have yielded disappointing results.In the mid-90’s I first reported on the finding that thee vaginal administration of Viagra for several days prior to the “hCG trigger “ or progesterone administration enhances uterine blood flow and estrogen delivery to the uterine lining and so improves endometrial thickening. Then In October 2002, I reported on the administration of vaginal Viagra to 105 women with repeated IVF failure due to persistently thin endometrial linings. All of the women had experienced at least two (2) prior IVF failures attributed to intractably thin uterine linings. About 70% of these women responded to treatment with Viagra suppositories with a marked improvement in endometrial thickness and 45% of these women achieved live IVF- births following a single cycle of treatment with Viagra. Nine percent (9%) miscarried. None of the women who had failed to achieve an improvement in endometrial thickness following Viagra therapy, subsequently and who underwent embryo transfers achieved viable pregnancies. 2.Uterine Pathology: It has long been suspected that anatomical defects of the uterus might result in infertility. While myomas (fibroids) embedded deep in the uterine wall, are unlikely to cause infertility, an association between their presence and infertility has been observed in cases where they distort the uterine cavity, or protrude as submucous polyps through the endometrial lining. It would appear that even small sub mucous myomas have the potential to prejudice implantation. Far too many infertile women found to have a partial or complete septum in the uterus are subjected to surgical excision of the septum with a promise that this will enhance subsequent implantation. This is an erroneous belief. Contrary to popular belief, the presence of a septum that partially or completely partitions the uterine cavity, while being responsible (in some cases) for late miscarriages and premature onset of labor, does NOT cause failed implantation.It is likely that most surface lesions in the uterine cavity, whether due to an endometrial, placental or fibroid polyp (no matter how small), or intrauterine adhesion’s, have the potential to interfere with implantation by producing a local “inflammatory”- type response, not too dissimilar in nature from that which is caused by a foreign body such as a intrauterine contraceptive device. Unfortunately, a dye X-Ray test (hysterosalpingogram/HSG) will often miss many smaller such lesions. The only reliable methods for diagnosing even the smallest of such lesions, is through the performance of a hysterosongram (HSN),a hysteroscopy or an MRI. Hysterosonogram (syn. Saline ultrasound): This procedure involves the trans-cervical injection of a physiological saline solution via a catheter, into the uterine cavity. The fluid distended cavity is then examined by vaginal ultrasound for any irregularities that might point to surface lesions such as polyps, fibroid tumors, scarring, or a uterine septum. If performed correctly, the HSN is highly effective in recognizing even the smallest surface lesions that protrude into the uterine cavity. It is less expensive, less traumatic, and diagnostically, equally reliable as hysteroscopy. The only disadvantage lies in the fact that if a lesion is detected, it may require the subsequent performance of hysteroscopic surgical approach to treating the problem..Hysteroscopy:Diagnostic hysteroscopy is an office procedure that is performed under intravenous sedation, general or local anesthesia, with minimal discomfort to the patient. The procedure involves the insertion of a thin, lighted, telescopelike instrument known as a hysteroscope through the vagina and cervix into the uterus in order to fully examine the uterine cavity. The uterus is first distended with carbon dioxide gas, which is passed through a sleeve adjacent to the hysteroscope. As is the case with FUS, diagnostic hysteroscopy facilitates examination of the inside of the uterus under direct vision for defects that might interfere with implantation. We have observed that approximately 8% of candidates for IVF have intrauterine lesions that require attention prior to undergoing IVF in order to optimize the chances of a successful outcome. We strongly recommend that all patients who have such lesions undergo surgery (D&C and/or hysteroscopic resection) to correct the pathology prior to undergoing IVF. Depending on the severity and nature of the pathology, therapeutic hysteroscopy may require general anesthesia. If so, it should be performed in an outpatient surgical facility or in a conventional operating room.
- Immunologic factors
The implantation process begins six or seven days after fertilization of the egg. At this time, specialized embryonic cells (i.e., the trophoblast), which later becomes the placenta; begin growing into the uterine lining. When the trophoblast and the uterine lining meet, they, along with Immune cells in the lining, become involved in a “cross talk” through mutual exchange of hormone-like substances called cytokines. Because of this complex immunologic interplay, the uterus is able to foster the embryo’s successful growth. Thus, from the very earliest stage of implantation the trophoblast establishes a foundation for the future nutritional, hormonal and respiratory interchange between mother and baby. In this manner, the interactive process of implantation is not only central to survival in early pregnancy but also to the quality of life after birth.Considering its importance, it is not surprising that failure of proper function of this immunologic interaction during implantation has been implicated as a cause of recurrent miscarriage, late pregnancy fetal loss, IVF failure, and infertility. A partial list of immunologic factors that may be involved in these situations includes anti-phospholipid antibodies (APA), antithyroid antibodies (ATA), and most importantly activation of uterine natural killer cells (NKa). Presently, these immunologic markers in the blood can be only adequately measured by a handful of highly specialized reproductive immunology laboratories in the United States. I personally use Reproductive Immunology Associates in Van Nuys, CA or Reprosource in Boston, MA.The Central role of Natural Killer cells: After ovulation and during early pregnancy, NK cells comprise more than 70% of the immune cell population of the uterine lining. NK cells produce a variety of local hormones known cytokines. Uncontrolled, excessive release of certain cytokines (i.e. TH-1 cytokines) is highly toxic to the trophoblast (“root system”) of the embryo” leading to their programmed death (apoptosis) and, subsequently to failed or compromised/dysfunctional implantation. In the following situations NK cells become activated, and start to produce an excess of TH-1 cytokines:
- Autoimmune Implantation Dysfunction: This is most commonly seen in association with a personal or family history of autoimmune diseases such as ith conditions such as Rheumatoid arthritis, hypothyroidism endometriosis and Lupus Erythematosus, Scleroderma, Dermatomyositis etc. It is also encountered in one third of women who have endometriosis (regardless of its severity), and in cases of “unexplained infertility” as well as with recurrent pregnancy loss (RPL).
- Alloimmune implantation dysfunction where the male and female partners share specific genetic (DQ-alpha and/or HLA) similarities This is commonly seen in cases of RPL and in cases of secondary infertility
Activated NK cells (NKa) can be detected through the K-562 target cell blood test and (more recently) through uterine biopsy for TH-1 cytokine activity. Treatment involves selective use of Intralipid (IL) or immunoglobulin (IVIG) therapy combined with oral steroids, initiated more 10-14 days prior to embryo transfer and in most cases of alloimmune implantation dysfunction, the transfer of a single blastocyst at a time.