Increased Endometrial Thickness on Day of Human Chorionic Gonadotropin (hCG) Injection Does Not Adversely Effect Pregnancy or Implantation Rates Following In Vitro Fertilization-Embryo Transfer (IVF-ET).

Abstract

An endometrium with insufficient thickness on the day of hCG has been reported by many authors to be associated with a lower pregnancy rate following IVF-ET. Weissman et al. (Fertil Steril, 1999) presented data also showing that increased endometrial thickness may also be associated with decreased fecundity in IVF-ET cycles. The purpose of this retrospective study was to either refute or corroborate the study by Weissman et al. All IVF-ET cycles, including patients up to age 48, where at least one embryo was transferred, and the endometrial thickness was performed on the day of hCG, were reviewed. All ultrasound records were reviewed and endometrial thickness was measured by one experienced sonographer to eliminate inter-observer variability. Endometrial thickness was measured in millimeters (mm) by placing calipers on the outer walls of the endometrium as seen in the longitudinal axis of the uterine body. The implantation and clinical pregnancy rates per cycles were compared by endometrial thickness levels. A total of 1,245 IVF-ET cycles were included. Endometrial thickness was found to be >14 mm in 106 cases (8.5% of cycles). The clinical pregnancy rates for women with an endometrial thickness measurement of 8–14 mm was 31.9% (n = 363 of 1,139) compared to 38.7% (n = 41 of 106) where endometrial thickness was >14 mm. The respective implantation rates were 14.4% (549/3,806) and 19.5% (70/358). The spontaneous abortion rates were also similar (15.1% vs. 14.6%). The mean number of embryos transferred were similar: 3.3 vs. 3.4 as were the ages (35.9 vs. 34.8). There was no difference in endometrial echo pattern according to endometrial thickness. In contrast to the study of Weissman et al., we do not find a lowered pregnancy rate or implantation rate in women whose endometrial thickness is >14 mm on day of hCG.