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Zorluk: ZorReproductive Endocrinology and Infertility

A 35-year-old nulligravid woman with a history of severe endometriosis is undergoing her first in vitro fertilization (IVF) cycle using a standard gonadotropin-releasing hormone (GnRH) antagonist protocol. Arrange the following pharmacological interventions and clinical steps of the IVF cycle in the correct chronological sequence, starting from the beginning of ovarian stimulation to the post-retrieval phase.

  1. 1Daily administration of exogenous follicle-stimulating hormone (FSH)
  2. 2Initiation of a GnRH antagonist
  3. 3Administration of a human chorionic gonadotropin (hCG) 'trigger' injection
  4. 4Transvaginal ultrasound-guided oocyte retrieval
  5. 5Initiation of supplemental progesterone therapy

Cevap

The correct chronological sequence for a standard GnRH antagonist IVF cycle is: 1) Exogenous FSH, 2) GnRH antagonist, 3) hCG trigger, 4) Oocyte retrieval, 5) Supplemental progesterone.
In a GnRH antagonist IVF cycle, the treatment begins with exogenous FSH to stimulate multifollicular growth. As follicles enlarge and estradiol levels rise, a GnRH antagonist is introduced (usually on stimulation day 5 or 6) to immediately block pituitary GnRH receptors, preventing a premature LH surge and spontaneous ovulation. Once ultrasound confirms the leading follicles have reached a mature diameter (18-20 mm), an hCG injection is given to mimic the natural LH surge, which induces final oocyte maturation and the resumption of meiosis. Transvaginal oocyte retrieval is strictly scheduled 34-36 hours post-hCG, just prior to expected follicular rupture. Finally, because the physical retrieval process depletes granulosa cells and the patient's endogenous pituitary function was suppressed, the resulting corpus luteum is inadequate; therefore, exogenous progesterone is mandatory for luteal phase support to allow for successful embryo implantation.

Adım Adım Çözüm

1
Identify the goal of the initial phase of the IVF cycle.
The first step is to stimulate multiple follicles using exogenous FSH.
Natural cycles typically yield one dominant follicle; IVF requires multi-follicular development to maximize oocyte yield.
2
Determine the necessary intervention as follicles mature and estrogen levels rise.
A GnRH antagonist must be initiated.
Rising estrogen from multiple developing follicles would normally trigger an LH surge, causing premature ovulation and cycle cancellation. The GnRH antagonist prevents this.
3
Identify the step required for final oocyte maturation once follicles are large enough.
An hCG 'trigger' is administered.
Oocytes must resume meiosis I and detach from the follicular wall, which is naturally driven by the LH surge and mimicked here by hCG.
4
Determine the timing of the procedural harvesting of the oocytes.
Transvaginal oocyte retrieval is performed.
This must be precisely timed (34-36 hours post-trigger) to capture mature oocytes just before they are naturally ovulated into the pelvis.
5
Identify the final required pharmacological support.
Initiation of supplemental progesterone.
The natural luteal phase is defective in IVF cycles due to the aspiration of hormone-producing granulosa cells and previous pituitary suppression, requiring exogenous support for endometrial preparation.

Anahtar Kavram

Pharmacological sequence and endocrinological rationale of controlled ovarian hyperstimulation in In Vitro Fertilization (IVF)
Tahmini Süre:1m 30s
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Konular

Reproductive Endocrinology and Infertility

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