Basic protocols of controlled ovarian stimulation: the tools we have

Nataliia Vladykina covers the basics — controlled ovarian stimulation as a craft whose mastery lies in constantly weighing whether what you do will bring more benefit or more harm.

The first question a clinician must answer before starting is why to stimulate. For natural conception the goal is monofollicular growth; for IUI, growing a few follicles is acceptable; for oocyte accumulation, freezing or embryo creation, the logic differs. Without a clear goal a protocol loses meaning.

The second step is the patient profile. By AMH, FSH and antral follicle count she is loosely classed as a normo-, hypo- or hyper-responder. These tools are not absolute and give no exact answer, but they help avoid trouble and choose a starting strategy.

The third choice is what to stimulate with: direct drugs (exogenous FSH) or indirect stimulants (clomiphene citrate, letrozole). Each has pros and cons; recent data lean toward letrozole, but in Ukraine its off-label status matters — hence the advice on a well-considered informed consent.

Basic protocols with indirect stimulants are reviewed: starting on day 5-6, closer to dominant-follicle selection, raises the chance of monofollicular growth. An important warning: clomiphene for longer than 5 days shifts the implantation window, making natural conception in that cycle problematic — a typical "protocol error."

The hardest stimulation, the speaker says, is for natural conception, where follicle and endometrial growth must be synchronised. If synchronisation fails, segmentation is wiser: retrieve oocytes and prepare the endometrium separately.

A separate case: patients not responding to indirect drugs. Hypogonadotropic hypogonadism needs exogenous FSH in small doses to achieve monofollicular growth and avoid an excessive response. An indicative dose table is given by AMH, FSH, follicle count, age and BMI.