In vitro fertilization (IVF) is a medical procedure used to assist with conception, involving a highly controlled sequence of steps to retrieve eggs, fertilize them, and transfer the resulting embryo. Success in an IVF cycle depends heavily on synchronizing the body’s natural reproductive processes with the timing of the fertility medications. Before the ovaries can be stimulated, the body’s normal hormonal cycle must be temporarily paused to ensure complete control over follicular development. This necessary preparation phase culminates in the ovarian suppression check, which confirms the body is ready for the next phase of treatment.
Defining the Ovarian Suppression Check
The ovarian suppression check is a diagnostic assessment that takes place after a patient has completed a period of medication intended to quiet the ovaries. This temporary suppression, often achieved using hormonal medications like birth control pills or gonadotropin-releasing hormone (GnRH) agonists, is referred to as downregulation. The check verifies that the ovaries are dormant and the body’s own hormone production is minimal. If the body is not adequately suppressed, the subsequent stimulation medications may not work as intended, potentially jeopardizing the entire cycle. The goal is to ensure a blank slate before introducing the drugs that promote egg growth.
The Purpose of Ovarian Suppression in IVF
The primary reason for suppressing ovarian function is to prevent the body from initiating a natural, premature release of eggs. In a typical menstrual cycle, the brain releases a surge of Luteinizing Hormone (LH) which triggers the release of a single mature egg in a process called ovulation. If this natural LH surge were to occur during an IVF cycle, the developing eggs would be released before the medical team could schedule the retrieval procedure. This would cause the cycle to be cancelled.
By suppressing the ovaries, physicians gain complete control over the timing of the egg development and retrieval. This downregulation allows the introduction of controlled doses of stimulation medication, which promotes the uniform growth of multiple follicles simultaneously. The suppression phase ensures that the eggs mature together at a predictable rate, maximizing the number of high-quality eggs collected during the retrieval procedure.
Components and Timing of the Suppression Check
The suppression check typically occurs after a patient has been on the downregulation medication for about ten to fourteen days. This timing allows sufficient time for the medication to fully take effect and quiet the hormonal system. The check involves two main components: a transvaginal ultrasound and a blood test to evaluate hormone levels.
The transvaginal ultrasound provides a visual assessment of the ovaries and the uterine lining. Physicians look specifically for the absence of any functional ovarian cysts, which are fluid-filled sacs that can produce hormones that would interfere with the controlled stimulation. The ultrasound confirms that there are no dominant follicles present, which are follicles larger than ten millimeters that might have escaped the suppression effects.
The blood test measures the circulating levels of specific reproductive hormones, primarily Estradiol (E2) and Progesterone (P4). A successful suppression is indicated by very low hormone levels, as the ovaries should not be actively producing them. For example, Estradiol levels are typically expected to be less than 50 picograms per milliliter (pg/ml), confirming the pituitary gland and ovaries are not active. Low Progesterone levels also confirm that no premature ovulation has occurred or is imminent.
Interpreting Results and Moving to Stimulation
A “passing” suppression check means that both the ultrasound and blood work confirm a state of ovarian dormancy. The ultrasound should show a quiet pelvis with small, resting ovaries and a thin uterine lining, while the hormone levels are at the required low baseline. Achieving this suppressed state is the green light for the patient to immediately begin the next stage, which is the controlled ovarian stimulation phase.
The patient then starts daily injectable medications, known as gonadotropins, which contain Follicle-Stimulating Hormone (FSH) to promote the growth of multiple follicles. If the check reveals a “failed” suppression, such as a large ovarian cyst or elevated Estradiol or Progesterone levels, the cycle cannot proceed immediately. The presence of high hormone levels or a dominant follicle indicates that the downregulation was incomplete.
In these cases, the medical team will often recommend an extension of the suppression medication for several more days or weeks, or they may choose to delay the cycle altogether. This clinical response is necessary to ensure the costly stimulation drugs are not wasted and that the ovaries are fully synchronized for optimal response. Only once the suppression criteria are met can the cycle safely transition to the stimulation phase.