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Quantification of the effect of pituitary down-regulation on 3D ultrasound predictors of ovarian response.

BACKGROUND
This study evaluated the effect of pituitary desensitization on ovarian volume, antral follicle count (AFC), and ovarian blood flow indices and their value as predictors of ovarian response during assisted reproduction treatment.


METHODS
A total of 115 subjects aged <40 years with follicle-stimulating hormone (FSH) levels <12 IU/l underwent transvaginal ultrasound in the early follicular phase of the menstrual cycle and after 14 days of down-regulation using gonadotrophin-releasing hormone agonists. 3D power Doppler was used to quantify ovarian volume, AFC and ovarian blood flow. The relationship between these ultrasound variables and treatment outcome was evaluated using multiple regression analysis.


RESULTS
Although a significant decrease in the ovarian volume (P < 0.05) and flow index (FI; P < 0.01) was demonstrated after pituitary desensitization, no differences were seen in the AFC. The total AFC, regardless of whether this was measured before or after down-regulation, was a significantly better predictor of the number of oocytes retrieved (P < 0.001) and poor ovarian response (P < 0.05) than age, FSH, ovarian volume and vascular indices although pre-treatment ovarian volume (P < 0.05) and FI (P < 0.05) were also predictive of the number of oocytes retrieved.


CONCLUSIONS
Pituitary desensitization results in a significant reduction in ovarian volume and vascularity, but has no effect on the AFC. AFC is the single best predictor of ovarian response regardless of whether the assessment is performed before or after down-regulation.