In spontaneous cycles both LH and FSH are secreted in a surge at midcycle. In in vitro fertilization (IVF) cycles, hCG administration results in elevation of LH-like activity only. The objective of this study was to compare the effectiveness of a single midcycle dose of GnRH agonist with hCG on follicular maturation. Eighteen IVF cycles in 14 women were randomized to receive either 0.5 mg leuprolide acetate or 5000 IU hCG at midcycle. Both groups underwent identical ovarian stimulation and cycle monitoring. On the day of GnRH agonist or hCG administration, estradiol concentrations and the number of follicles 1.5 cm or larger were the same in both groups. Mean serum LH and FSH levels were elevated for 34 h after GnRH agonist administration. In contrast, mean serum hCG levels were elevated for approximately 6 days after the administration of hCG, and serum FSH levels did not change. Mean luteal phase serum estradiol concentrations were lower in the GnRH agonist group than in the hCG group (P less than 0.02). No differences were observed in mean serum progesterone or PRL during the luteal phase or in the length of the luteal phase in the two groups. The mean number of oocytes retrieved and embryo number and quality did not differ between the two groups. Three of nine GnRH agonist cycles and none of nine hCG cycles resulted in clinical pregnancy (P = 0.1). The results of this study indicate that GnRH agonist is able to simulate a midcycle surge of gonadotropins, leading to follicular maturation and pregnancy. Further work is needed to determine whether there is any clinical advantage of GnRH agonist over hCG administration with regard to pregnancy rates.

The texture and the thickness of the endometrium as assessed by transvaginal sonography were prospectively evaluated in 123 patients undergoing IVF treatment. Three different types of endometrial patterns could be distinguished: (A) an entirely homogenous, hyperechogenic endometrium; (B) an intermediate type characterized by the same reflectivity of ultrasound as the myometrium, with a nonprominent or absent central echogenic line; and (C) a multilayered endometrium consisting of prominent outer and midline hyperechogenic lines and inner hypoechogenic regions. On the day before oocyte retrieval, endometrial thickness was significantly greater in the group of patients who achieved pregnancy than in the group who did not (8.7 +/- 0.4 vs 7.5 +/- 0.2 mm, respectively; P less than 0.01) and significantly more patients had multilayered, pattern C, endometrium (75% in pregnant women vs 42.4% in nonpregnant women; P less than 0.01). No pregnancy occurred when the endometrial thickness was less than 6 mm. When type C endometrium greater than or equal to 6 mm thick was seen, the pregnancy rate per embryo transfer was 39%. When type A or B endometrial pattern was seen, the negative predictive value for the occurrence of pregnancy was 90.5%. Our results suggest that transvaginal sonographic evaluation of endometrial texture and thickness may be an indicator of the likelihood of achieving pregnancy.

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We recently demonstrated, using transvaginal sonography, that conception cycles in in-vitro fertilization (IVF) are associated with a significantly thicker endometrium at midcycle than non-conception cycles, suggesting that endometrial growth may influence implantation. In the present study, to examine whether the type of stimulation protocol affects endometrial development, we compared the sonographic appearance of the endometrium in 22 patients randomized to receive clomiphene citrate and human menopausal gonadotrophin (CC/HMG) and in 19 who received HMG alone. A significantly thicker endometrium was observed in the HMG patients compared to the CC/HMG group (P less than 0.005) throughout the follicular phase of the cycle, although serum concentrations of oestradiol (E2) did not differ in the two groups. Twenty-three patients (13 in the HMG group and 10 in the CC/HMG group) had previous IVF cycles with CC/HMG stimulation in which endometrial thickness was measured. A thin endometrium recurred with subsequent CC/HMG cycles while increased growth occurred with HMG only compared to previous CC/HMG cycles. Therefore, ultrasound examination of the endometrium in this study demonstrated that CC results in a thinner endometrium than HMG alone. We believe these findings may be of importance in improving pregnancy rates in IVF and possibly in other infertility therapy which involves the use of clomiphene citrate.

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