When eggs don’t implant successfully during IVF treatments, it often feels frustrating and upsetting – and many factors can play a role, adding to the confusion. Learn more about the important elements of egg implantation below.
We suspect embryos are healthy when they are blastocysts (embryos that have matured and developed more), particularly those that reach the blastocyst stage “on schedule” by day five. We’re even more confident when we have done pre-implantation genetic screening to check that the embryo seems to have healthy chromosomes. Finally, when transferring the embryo, we’re optimistic when the embryo transfer bubbles to within 15 mm of the fundus of the uterus – the sweet spot for an egg.
When we’re checking out your uterus, we like to rule out polyps, fibroids, scar tissue or midline structures (“subseptum”) that could potentially harm implantation. This is best done through either a sonohystogram (using ultrasound imaging) or a hysteroscopy (a day procedure). It isn’t clear which of the two procedures is better, and different doctors will suggest different options.
We also like to investigate your fallopian tubes: they can be very dilated, causing a hydrosalpinx and leakage of fluid into the cavity. This is best diagnosed through either an HSG (x-ray test), or through laparoscopy. We also often see it during a transvaginal ultrasound.
We can also look at the lining of your uterus. The standard method is to inspect your endometrial thickness. We need at least 7 mm, many doctors like 8 mm, and some studies suggest that implantation is best between 9 mm and 10 mm.
Some doctors do an endometrial biopsy to analyze it further. This is controversial, as it doesn’t really work as well as we would like. That said, some tests include Harvey Kliman’s Endometrial Function Test, the “E-tegrity Assay” for beta-3 integrin, and sending a biopsy specimen off for analysis.
Evaluating your health can be tricky. There are some steadfast rules: your prolactin numbers should be less than 30, and your TSH levels should be less than 5 (some doctors suggest less than 2.5 or even less than 2).
Historically, when we were worried about recurrent implantation failure or recurrent pregnancy loss, we would check for coagulation (blood that is too thick for successful ongoing implantation) and immune system dysfunction (cells that attack your developing embryo).
While we still test for it, coagulation testing rarely comes up positive, and doesn’t always make it clear whether treatment is necessary or helpful. For a long time, we hoped that using blood thinners would make a great difference. That’s why doctors often suggested baby aspirin (ASA 81 mg a day) for women with implantation problems. But newer research suggests that it isn’t very effective. A stronger alternative might be low-molecular weight heparins, such as Lovenox or Fragmin.
Testing for immune system dysfunction is even more disputed. Repeated testing can create fluke positives. And the treatments for immune system disorders, such as steroids and intravenous immunoglobulins, is extremely controversial. For clinics outside of a research protocol, some approaches can be risky and even irresponsible.
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