THE USE OF DOUBLE OVARIAN STIMULATION (DUAL-STIM) AND ITS PECULIARITIES: A REVIEW

Since the emergence of controlled ovarian stimulation (COS) techniques, one of the greatest challenges for specialists in human reproduction is the customization and optimization of treatments aimed at patients with an unfavorable prognosis, which affects up to 24% of women undergoing in vitro fertilization (IVF) 1, 2. The exponential increase in the number of poor responders is also due to the strong and increasing insertion of women in the labor market, which has considerably increased late maternity rates 3.

Knowing that women have limited reproductive potential, with progressive depletion of the follicular population throughout their lives, truly effective strategies for the management of these patients are constantly being sought, as well as more specific ways of classifying them 4.

In order to standardize the classification of infertile patients in poor responders, in 2011 the Bologna criteria were developed by ESHRE. Soon after, the POSEIDON group also proposed some changes in these concepts creating subgroups of more homogeneous classifications, and the concept of sub-optimal response. This new classification system should help doctors and patients to promote shorter times until pregnancy 2,5.

Therefore, to optimize the treatments of this population, different strategies have emerged aiming at obtaining more oocytes and embryos in the shortest possible time2. Stimulations with high dosages of different classes of gonadotropins, antioxidants, use of pre-stimulation androgens, inositol, melatonin and other alternative treatments have shown varied results and their use has remained in constant contradiction in the current Scientific Society 6,7,8,9.

In parallel, emergency COS protocols were also created for cancer patients, in which the need to obtain oocytes quickly to preserve fertility prior to gonadotoxic treatments is essential. In addition, the survival of these women has progressively increased in recent years, with advances in early diagnosis methods and their more effective treatments, making possible future pregnancies feasible 10.

Immediately after starting treatment their COS is performed, often in the luteal phase of the menstrual cycle. In principle doubts arose about the real possibility of obtaining oocytes with this strategy, given the concept widely accepted and widespread in the literature about a single wave of follicular recruitment per menstrual cycle 11,16.

However, recently conducted studies have shown similar amounts of oocytes obtained in these situations when compared to “classic” stimulation. In assessing the quality of these gametes, embryonic development capacity comparable to standard protocols also confirmed their viability 12.

Taking this into consideration, two ovarian stimulations were then proposed in the same menstrual cycle, in order to optimize the results of reproductive treatments. Without presenting the classic ovarian rest between the follicle aspiration and the beginning of treatments with gonadotropins, the subsequent stimulation begins only 5 days after the extraction of oocytes (in luteal phase), receiving the name of Dual-Stim.

Knowing that the live births rates is proportional to the amount of oocytes obtained during fertility treatments, strategies such as this would provide higher success rates by intention to treat, with good treatment tolerability 12.

Therefore, this strategy started to be used mainly in patients with poor prognosis, where the obtaining of oocytes per stimulation is small, and the need to perform multiple stimulation until obtaining a significant amount of oocytes to fertilize and generate a viable embryo can take time 10,12,13.