PROSPECTIVE EVALUATION OF ENDOMETRIAL THICKNESS AS A PREDICTOR OF PITUITARY DOWN-REGULATION AFTER GONADOTROPIN-RELEASING-HORMONE ANALOG ADMINISTRATION IN AN IN-VITRO FERTILIZATION PROGRAM

Objective: To determine whether pituitary down-regulation after gonado tropin-releasing hormone analogue (GnRH-a) administration can be accur ately predicted by transvaginal ultrasonographic measurement of endome trial thickness. Design: Prospective study. Setting: An IVF unit of an academic medical center. Patient(s): One hundred eighty-one patients undergoing 265 NF-ET treatment cycles using GnRH-a in the long protoco l. Main Outcome Measure(s): Serum concentrations of E-2 were determine d, and endometrial thickness was measured by transvaginal sonography. The accuracy of endometrial thickness for predicting pituitary down-re gulation was calculated. Result(s): Pituitary down-regulation, defined as a serum E-2 concentration of less than or equal to 55 pg/mL, was a chieved in 77% (204 of 265) of the cycles. An endometrial thickness of less than or equal to 6 mm was found in 92.2% (188 of 204) of cycles in which down-regulation was achieved. An estradiol level of less than or equal to 55 pg/mL was present in 95.9% (188 of 196) of cycles with endometrial thickness of less than or equal to 6 mm. Conclusion(s): A state of relative hypoestrogenism after GnRH-a administration, indica tive of pituitary down-regulation, can be predicted with a high degree of accuracy by ultrasonographic measurement of endometrial thickness. Thus, routine testing for serum E-2 concentration may be safely omitt ed. This may allow further simplification of IVF protocols and increas e both cost-effectiveness and patients' convenience. (C) 1998 by Ameri can Society for Reproductive Medicine.