Preimplantation Genetic Testing for Aneuploidy (PGT-A) has significantly enhanced embryo selection during in vitro fertiliza tion by identifying chromosomal abnormalities before embryo transfer. While PGT-A has improved embryo selection strategies, the identification of embryos classified as mosaic—containing both euploid and aneuploid cell populations—has introduced substantial clinical and ethical uncertainty.

Historically, many fertility clinics have discouraged or pro hibited the transfer of high-level mosaic embryos because of concerns regarding implantation failure, miscarriage, congenital anomalies, and uncertain developmental outcomes. However, accumulating evidence suggests that some mosaic embryos re tain reproductive potential and can result in healthy live births. Furthermore, limitations in current PGT-A technology may con tribute to false-positive diagnoses and imperfect prediction of embryonic developmental potential.

As the scientific understanding of embryo mosaicism con tinues to evolve, clinicians must navigate the complex balance between patient autonomy, institutional policies, and ethical responsibility. This case report describes the transfer of a high level mosaic embryo following an extensive multidisciplinary in formed consent process and proposes a framework for clinical decision-making in similar cases.

A 43-year-old woman undergoing publicly funded IVF with ICSI produced three blastocysts suitable for PGT-A analysis. Next-generation sequencing identified two aneuploid embryos and one high-level mosaic embryo demonstrating mosaic tri somy 2 and partial trisomy 20pter-p11.23.

Because the clinic maintained a policy against transferring high-level mosaic embryos, the case required individualized re view. Despite counselling regarding potential risks and uncer tainties, the patient and her partner expressed a strong desire to proceed with the transfer of the mosaic embryo.

The case was reviewed by the clinic’s ethics committee and subsequently approved for consideration under exceptional cir cumstances. Written informed consent was obtained from the patient for both treatment and publication of this case report.

Multidisciplinary informed consent process

Genetic counseling

The patient underwent extensive counselling with a certified genetic counsellor. Discussions focused on the biological basis of embryo mosaicism, limitations of PGT-A testing, potential diagnostic inaccuracies, and the range of possible reproductive outcomes. Potential outcomes reviewed included failed implan tation, miscarriage, congenital abnormalities, chromosomal dis orders, and healthy live birth.

Particular emphasis was placed on the uncertainty associ ated with mosaic embryo transfer and the inability of current testing technologies to predict fetal outcomes with complete accuracy.

Ethics review

Given the proposed deviation from institutional policy, the case underwent formal ethics review. The committee evaluated patient autonomy, reproductive rights, potential risks to the future child, and the broader implications of permitting transfer of high-level mosaic embryos.

The committee concluded that proceeding with treatment was ethically permissible provided that comprehensive coun selling was documented and the patient demonstrated a clear understanding of the associated risks and uncertainties.

Legal consultation

A reproductive law specialist reviewed the case to ensure compliance with applicable regulations and standards of care. Legal consultation focused on documentation of informed de cision-making, provider responsibilities, and liability consider ations.

Recommendations from the legal review informed the devel opment of a customized informed consent document specific to the transfer of a high-level mosaic embryo.

Customized informed consent

A detailed consent document was developed outlining:

• The embryo’s specific genetic findings.

• Current evidence regarding outcomes associated with mo saic embryo transfer.

• Limitations of PGT-A technology.

• Potential maternal, fetal, and neonatal risks.

• Available alternatives include additional IVF cycles, donor gametes, donor embryos, adoption, or discontinuation of fertility treatment.

The consent document explicitly stated that the clinic does not routinely recommend transfer of abnormal embryos be cause of increased risks, including miscarriage, stillbirth, con genital abnormalities, severe lifelong disability, maternal com plications, and neonatal mortality.

Limitations of prenatal screening and diagnostic procedures, including amniocentesis, were also reviewed. The patient and her partner acknowledged understanding these risks and con firmed that their decision to proceed was voluntary and in formed. The final document was reviewed and signed by the patient, her partner, and the attending physician.

Psychosocial support

Recognizing the emotional complexity of the decision, psy chological counselling was offered to assist the patient in pro cessing uncertainty, managing expectations, and ensuring that the decision was made free from coercion or misunderstanding.

Clinical outcome

Following completion of the multidisciplinary review and consent process, the patient underwent frozen embryo transfer. Pregnancy was achieved following the transfer of the high-level mosaic embryo. Prenatal evaluation included NIPT, serial ultra sonography, and diagnostic amniocentesis. All investigations demonstrated normal fetal development and no evidence of chromosomal abnormalities.

The pregnancy progressed without major complications, re sulting in the delivery of a healthy female infant. Developmental assessment at three months of age was reported as normal.

This case highlights the complex ethical and clinical consid erations surrounding the transfer of high-level mosaic embryos. Although institutional policies are designed to promote patient safety and standardize care, rigid exclusion of all mosaic em bryos may not fully reflect the current scientific literature.

Several studies have demonstrated that mosaic embryos re tain developmental potential and may result in successful preg nancies and healthy live births. Greco and colleagues reported successful live births following transfer of mosaic blastocysts, challenging the assumption that all mosaic embryos are non viable. Additionally, limitations in PGT-A technology may con tribute to false-positive mosaic diagnoses, further complicating clinical decision-making.

The successful outcome observed in this case does not elimi nate the risks associated with mosaic embryo transfer; however, it demonstrates that favourable outcomes remain possible when patients are appropriately selected and thoroughly counselled.

The informed consent process served as the cornerstone of ethical decision-making in this case. Through collaboration among genetics, ethics, legal, medical, and psychological pro fessionals, the patient was empowered to make an informed decision while ensuring that clinicians fulfilled their ethical ob ligations.

Proposed framework for informed consent

Based on this case and existing professional guidance, the following framework may assist clinics considering the transfer of mosaic embryos:

1. Comprehensive education regarding mosaicism, PGT-A limi tations, and available evidence.

2. Shared decision-making that respects patient values and re productive goals.

3. Multidisciplinary review involving genetics, ethics, legal, and psychosocial experts when appropriate.

4. Detailed documentation of risks, uncertainties, alternatives, and patient understanding.

5. Ongoing prenatal and postnatal follow-up when pregnancy is achieved.

As assisted reproductive technologies continue to evolve, clinical and ethical frameworks must evolve alongside them. This case demonstrates that transfer of a high-level mosaic em bryo can be ethically considered within a structured multidis ciplinary framework that prioritizes informed consent, patient autonomy, and careful clinical oversight.

Future research should focus on improving the interpreta tion of mosaic PGT-A findings, refining embryo selection algo rithms, and establishing evidence-based guidelines that sup port individualized patient care while maintaining the highest standards of safety and ethical practice.

Ethics approval and patient consent

The case was reviewed and approved by the clinic’s ethics committee. Written informed consent was obtained from the patient for treatment and publication of this case report.

Funding

No external funding was received for this study

Conflict of interest

The authors declare no conflicts of interest.

Author contributions

All authors contributed to the conception, preparation, re view, and approval of the final manuscript.