Even with modern techniques like PGT-A and highly controlled IVF environments, embryo transfers can fail. That includes cases involving genetically normal (euploid) embryos, transferred into healthy, screened uteruses, whether it’s the patient’s or a surrogate’s.
At SILK Medical, where many programs include PGT-A and involve donor eggs or gestational carriers, this question often comes up after the first attempt fails: “If the embryo was perfect, what went wrong?”
The short answer: implantation is more complex than just genetics.
The Myth of the “Perfect Embryo”
Preimplantation Genetic Testing for Aneuploidy (PGT-A) screens embryos for major chromosomal abnormalities – extra or missing chromosomes that are known to prevent implantation or cause miscarriage. But a genetically “normal” result doesn’t tell the full story. PGT-A doesn’t detect smaller genetic variations, metabolic health, structural embryo damage, or its ability to signal properly with the uterine lining.
A normal karyotype improves chances, but it doesn’t guarantee success. In fact, even with a top-quality embryo, implantation rates per transfer rarely exceed 65–70%, even in top global clinics like SILK Medical. According to studies published by reputable reproductive medicine organizations, the success rates of embryo transfer fluctuate depending on multiple factors, highlighting the complexity of implantation processes.
Implantation Requires More Than Just a Healthy Embryo
Implantation is a finely tuned biological process that relies on two separate systems: the embryo and the uterus. Even when one is in ideal condition, the other may fall slightly out of sync.
For implantation to occur, the embryo must communicate with the endometrium during a short window of receptivity. This involves hormonal, biochemical, vascular, and even immunological signals. A mismatch in any of these, even in the absence of visible abnormalities, can prevent successful attachment.
Synchrony Between Embryo and Endometrium Matters
The so-called “window of implantation” typically spans only a few days. If the embryo is transferred slightly too early or too late relative to the endometrial development, it may simply arrive at a non-receptive moment.
This is why endometrial preparation is not just about medication doses. Timing and hormonal response monitoring play an important role. SILK Medical uses individual protocols and precise cycle monitoring (often in surrogacy programs) to align endometrial receptivity with embryo development stage.
In Surrogacy, Some Factors Remain Hidden
Even after extensive medical screening, surrogate mothers may have minor uterine or immune factors that don’t show up in routine exams. These can include low-grade chronic inflammation, undetected clotting tendencies, or subtle imbalances in the uterine microbiome.
All surrogate candidates at SILK Medical undergo hormonal, infectious, and structural evaluation, but not every factor influencing receptivity is measurable. That’s one reason even screened surrogates with previous successful births can sometimes experience a failed transfer.
Lab Conditions and Embryo Handling Also Play a Role
Embryo development in the lab is sensitive to oxygen levels, pH balance, temperature, and other environmental conditions. Even minor handling stress during freezing and thawing may impact the embryo’s potential, especially if cumulative stress builds up over multiple stages.
To minimize this, SILK Medical uses advanced time-lapse incubators (AI EmbryoScope) that reduce disturbance during culture, and the IVFID Witness system to track every handling step. This minimizes both technical errors and external stress factors that can affect outcome.
Not All “Normal” Embryos Are Equal
Another possibility is mosaicism. An embryo may test as normal in a small biopsy taken from its outer layer (the trophectoderm), while the inner cell mass, destined to become the fetus, contains a mix of normal and abnormal cells. PGT-A cannot detect all forms of mosaicism or predict its impact on implantation.
In other cases, the embryo may simply lack sufficient metabolic activity, energy reserves, or cellular cohesion to successfully attach, even though its chromosomes appear normal.
What SILK Medical Does to Reduce Failure Risk
Embryo selection is only one part of a broader chain. SILK Medical combines:
- Full hormonal tracking during preparation
- Individual endometrial synchronization protocols
- Advanced embryo culture with time-lapse monitoring
- PGT-A by experienced genetic labs
- Surrogate selection with strict medical, psychological, and lifestyle standards
- Double-check systems like IVFID Witness to reduce lab-related risks
Even with all this, some failure is unavoidable. That’s why many of SILK’s programs include more than one transfer or even offer guaranteed live birth packages, especially in surrogacy with donor eggs.
When to Try Again
One failed transfer isn’t always a sign of deeper problems. In most cases, the next transfer from the same batch of embryos succeeds, especially when the embryo quality, endometrial response, and surrogate preparation remain favorable.
If two or more euploid embryo transfers fail, the clinical team may recommend additional tests (such as ERA or immune panel), a second IVF cycle, or revisiting surrogate match criteria.
Implantation Failure Doesn’t Mean the Embryo Was Bad
Embryo implantation is one of the least predictable steps in assisted reproduction. Even when everything appears optimal, like genetically normal embryos, healthy surrogate, high-quality lab, some natural variables remain beyond control or measurement.
SILK Medical works to reduce those unknowns with a combination of technology, experience, and precision. While no system can guarantee implantation from a single embryo, each failed transfer helps improve strategy, increase knowledge, and guide the next steps.
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