Should Surrogates Be Screened for Endometriosis or Immune Factors?

By Emanuela Lazzaroni Tealdi, MSc Senior Embryologist and Clinical Fertility & Reproductive Immunology Specialist, ESSI

Surrogacy is rarely the first step in a family-building journey. It is often pursued after a long, complex, and emotionally taxing medical road.

For many intended parents, the decision to use a gestational carrier does not only come after repeated IVF failures. In many cases, it reflects a stark medical reality: they may not have the ability to safely carry a pregnancy to term due to severe uterine factors, advanced endometriosis, adenomyosis, or other systemic conditions.

By the time surrogacy is considered, the embryos have frequently already been created, genetically tested, and are often strictly limited in number. At this stage, the clinical expectations are incredibly clear: if a healthy, euploid embryo is transferred into a healthy uterus, implantation should seamlessly occur.

But unfortunately, this is not always the case. When everything looks perfect on paper but the outcome still fails, we have to ask a critical question.

The Current Assumption in Surrogacy Screening

In most standard surrogacy programs, the medical screening of a potential gestational carrier focuses on overt pathology:

• General medical history

• Past obstetric history (proof of prior uncomplicated pregnancies)

• Uterine anatomy (evaluated via standard ultrasound or saline sonogram)

• Infectious disease screening

These protocols are absolutely essential and appropriate. However, they are primarily designed to rule out obvious structural or infectious barriers. They do not always capture the more subtle, underlying biological factors that dictate whether an embryo will successfully implant and progress.

If the embryo’s quality has already been optimized, and if the surrogate’s uterus appears structurally normal, should we be evaluating the biological environment of the surrogate more deeply?

The Hidden Threat: “Silent” Endometriosis

Endometriosis is most commonly associated with debilitating pelvic pain. However, it is vital to recognize that the disease can also be entirely asymptomatic.

Even in the complete absence of pain, “silent” endometriosis fundamentally alters the pelvic and uterine environment. It has been clinically associated with:

• Altered inflammatory signaling

• Toxic changes in cytokine profiles

• Impaired endometrial receptivity

Emerging evidence proves that the systemic inflammation caused by endometriosis can actively reject or damage an embryo, severely negatively affecting implantation even when the embryos themselves are of the highest quality.

In the context of surrogacy, this raises a profound consideration. A surrogate may easily pass all standard agency criteria, feel perfectly healthy, and still harbor underlying inflammatory factors that create a hostile environment for implantation.

Adenomyosis and Pregnancy Outcomes

Similarly, adenomyosis—a condition where endometrial-like tissue grows deep into the muscular wall of the uterus—is frequently underdiagnosed on standard imaging.

Adenomyosis has been increasingly associated not only with implantation challenges but also with adverse pregnancy outcomes, including second-trimester complications, premature labor, and pregnancy loss. In a setting where intended parents have already lost the ability to carry a pregnancy themselves, subjecting their precious embryos to these hidden risks takes on devastating significance.

The Immune Component of Implantation

Implantation is not merely a structural or hormonal process; it is a highly complex immunologic event.

For an embryo to successfully attach and grow, the uterus must achieve a delicate balance between immune tolerance (accepting the foreign DNA of the embryo) and controlled inflammatory signaling (which is necessary for tissue remodeling).

Disruptions in this delicate balance have been heavily associated with recurrent implantation failure and early pregnancy loss. While the role of comprehensive immune testing remains an area of ongoing discussion in general fertility circles, there is a rapidly growing recognition that, in selected complex cases, immune dysregulation is the missing piece of the puzzle.

Why This Matters So Deeply in Surrogacy

Surrogacy represents an immense financial investment, a major emotional commitment, and, in many cases, the only remaining path to parenthood.

When a transfer fails under these conditions—when embryos are limited and the stakes are at their absolute highest—the impact is profound. It begs the medical community to ask: is the current baseline level of surrogate screening truly sufficient, or is there an urgent need for a more refined, biologically intelligent approach?

A Balanced Perspective: Moving Toward Informed Selection

It is important to emphasize that not every surrogate requires extensive, invasive testing, and not every failed transfer is due to endometriosis or immune factors. The goal here is not to over-medicalize the surrogacy process or create unnecessary barriers.

The goal is to recognize that implantation is biologically complex, and to understand that standard screening simply does not capture all relevant factors.

At ESSI, we believe additional evaluation should be strongly considered in specific contexts, such as:

• A surrogate who experiences repeated, unexplained failed transfers of high-quality embryos.

• Instances of unexplained early pregnancy loss in a surrogate.

• A clinical history or subtle imaging findings suggestive of underlying inflammatory or gynecologic conditions.

The ESSI Perspective: An Integrated Lens

At ESSI, we believe that reproductive outcomes must be interpreted through an integrated lens. This includes evaluating the embryo biology, the uterine environment, and the immune and inflammatory context as one cohesive system.

Whether we are treating the intended parents or evaluating a surrogacy journey, the fundamental principle remains exactly the same: understanding the full biological picture allows for more informed, intelligent decisions.

As reproductive medicine continues to evolve, so must the questions we ask. Looking beyond standard screening to truly understand the environment in which implantation occurs is not about creating hurdles. It is about improving clarity, drastically reducing uncertainty, and supporting the best possible outcomes for patients who have already invested so much in their journey to build a family.

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Considering Your Next Steps? If you are currently navigating the complexities of surrogacy and have questions about embryo transfer outcomes, implantation failures, or the biological factors that dictate success, a more detailed evaluation can provide the clarity you need. At ESSI, the Fertility and Immunology team provides expert guidance designed to interpret your full clinical picture and help define the safest, most effective path forward.