Who is the DuoStim protocol indicated for? Transfer, vitrification, and safety

The DuoStim protocol has established itself as an effective tool in assisted reproduction, especially in women with poorer prognoses. Unlike other approaches that may be insufficient or lead to frustration, this protocol improves clinical and emotional outcomes.

Most common clinical indications

The patients who benefit most from DuoStim are:

• Women with low ovarian reserve.
• Patients of advanced maternal age.
• Women who require a greater number of oocytes to achieve viable embryos.

This protocol allows more embryos to be obtained, which increases the chances of achieving at least one with normal genetic material and high implantation potential.

In addition, there are other profiles in which DuoStim can make a difference:

• Cancer patients who need to preserve their fertility before starting gonadotoxic treatments.
• Couples who are carriers of genetic abnormalities and need a greater number of embryos to perform preimplantation genetic diagnosis (PGT-A).
• Cases of severe male factor infertility that may make it difficult to obtain viable embryos.
• In general, couples with a poorer reproductive prognosis, where time and embryo quality are critical factors.

Is fresh transfer possible after DuoStim?

The answer depends on the type of double stimulation applied:

• In the classic protocol (stimulation in the follicular phase followed by another in the luteal phase), a fresh transfer cannot be performed, as the endometrium is not in optimal condition. In addition, most of these patients require genetic testing of the embryos, which justifies vitrification.
• However, there are other less common variants of DuoStim, where the first stimulation is performed in the luteal phase and the second in the follicular phase (start of the next cycle). In these cases, a fresh transfer can be considered, as it is not essential to preserve the embryos if PGT-A is not going to be performed.

What happens to the embryos obtained?

In most cases, embryos are vitrified after blastocyst culture, especially when the following is required:

• Performing PGT-A.
• Correctly synchronising the endometrium before transfer.
• Reducing the risk of multiple pregnancies.
• Planning deferred transfers under more favourable conditions.

Vitrification allows high-quality embryos to be preserved safely and effectively, maintaining their viability intact until the right time for transfer.

Are oocytes and embryos obtained during the second stimulation safe?

According to recent studies, such as those by Vaiarelli and Cerrillo’s group, oocytes obtained during the second stimulation are just as viable as those obtained during the first:

• Same fertilisation rate.
• Same probability of reaching the blastocyst stage.
• Same genetic quality (euploidy).
• Equivalent clinical, obstetric and neonatal outcomes.

This evidence supports the safety of double stimulation from a reproductive, genetic and medical point of view.

Conclusion

The DuoStim protocol is particularly indicated for women with low ovarian reserve or advanced maternal age, as well as other patient profiles with poor prognosis. Embryo vitrification is a common part of this strategy, and its safety has been widely validated. Although fresh transfer is not possible in most cases, there are alternatives tailored to each patient’s needs.

Thanks to this approach, many women have been able to obtain oocytes and embryos that would not have been possible in conventional cycles.