Endometrial pattern on the day of oocyte retrieval is more predictive of implantation success than the pattern or thickness on the day of hCG administration

Purpose: Multiple studies have confirmed a lower implantation (IR) and preg nancy rate (PR) in women who exhibit a homogeneous pattern (pattern II) of the endometrium compared to a triple-line pattern (pattern I) on the day of hCG administration. However, no data are available to evaluate if patients alter their endometrial thickness and pattern between the day of hCG admin istration (D-hCG) and the day of oocyte retrieval (D-RET) and whether these changes adversely affect endometrial receptivity. Methods: We prospectively evaluated 86 women (mean age, 32.9 +/- 3.8 years; range, 24-40 years) undergoing 103 IVF/ET cycles. Results: Pattern II was noted in 7 cycles (6.8%) on D-hCG compared to 96 cy cles with pattern I (93.2%). However; 20 cycles (19.4%) had pattern II on D RET: The ongoing IR was 13.0% (3/23) In the pattern II group compared to 20 .8% (76/365) in the pattern I group on D-hCG (P = NS). However, a significa nt decrease in the ongoing IR, to 9.9% (7/71), was noted in pattern II, com pared to 23.3% (71/305) in pattern I, on D-RET (P = 0.019). There was no di fference in age, basal FSH, peak E-2, P-4 on the day of hCG, number of oocy tes, number of ET or endometrial thickness between pregnant and nonpregnant patients, or between patients with pattern I and those with pattern II. A trend toward higher progesterone levels on Di,ce was noted in women with pa ttern II (P = 0.078). Conclusions: Endometrial pattern, rather than thickness, on the day of oocy te retrieval appears to be an important prognosticator of endometrial recep tivity.