Relationship between follicular volume and oocyte competence, blastocyst development and live-birth rate: optimal follicle size for oocyte retrieval
Abstrakt
Objectives: To analyse the oocyte competence in GnRHa stimulation cycles with regard to maturity, fertilization and blastocyst rate and clinical outcome (pregnancy and live birth rate) in correlation to follicular volume measured by 3D sonography and follicular fluid composition. Methods: This was a prospective single-centre study conducted in the period June 2012 - June 2014 including 118 ovum pick-ups (OPUs) with subsequent embryo transfers (ET).
Out of 1,493 aspirated follicles we analysed 1,236 follicles and traced oocytes grouped according to follicular volume. Follicular volumes were evaluated using 3D ultrasound during oocyte retrieval.
Oocyte maturity and blastocyst development was tracked according to follicular volume. Ovarian stimulation was performed using the GnRHa long protocol.
Intrafollicular concentrations of estradiol (E2), testosterone (T), progesterone (P), luteinizing hormone (LH), follicle-stimulating hormone (FSH) and granulocyte-colony stimulating factor (G-CSF) were quantified by immunoassay. Clinical outcome in terms of implantation rate (IR), (clinical) pregnancy rate (PR), miscarriage and live birth rate (LBR) was evaluated.
Results: Although MII oocyte recovery rate was significantly lower for small follicles compared to larger ones (8-12mm/0.3-0.9mL: 63.8% vs. 13-23mm/1-6mL: 76.6% and GREATER-THAN OR EQUAL TO 24mm/GREATER-THAN OR EQUAL TO6mL: 81.3%; P-value 6mL was observed (LBR: 54.5%, 42.0%, and 41.7%, respectively; n.s.). No predictive value of follicular fluid (FF) biomarkers was found.
Conclusions: Our data indicate that the optimal follicular volume for a high yield of good quality blastocysts with good potential to lead to a live birth is between 13- 23mm/1-6mL. However, oocytes derived from small follicles 8-12mm/0.3-0.9mL still have the capacity for normal development and subsequent delivery of healthy children, suggesting that aspiration of these follicles increases the number of blastocysts per stimulation.