Early embryo development in women with endometriosis: a retrospective study

Abstract

Background: Endometriosis (EN) is known to be detrimental to fertility in many ways. Evidence drawn from oocyte recipient cycles
suggests compromised oocyte quality in endometriosis. This retrospective case-control study aimed to evaluate embryo quality in
women with endometriosis compared to those with tubal factor (TF) or unexplained infertility.

Methods: IVF cycles from two fertility centres were retrospectively analysed for oocyte yield, fertilisation, early embryo arrest and
blastocyst formation. Multicentre retrospective studies were performed. Treatment cycles and embryology records of women with
and without endometriosis undergoing IVF were reviewed via the IDEASTM database. The number of oocytes collected per mature
follicle, fertilisation rate, pregnancy rate, morphology and morphometric assessment of the embryo at all stages were evaluated.

Results:
Women with endometriosis had fewer oocytes per mature follicle and a higher proportion of embryos that failed to reach
the 8-cell stage. However, fertilisation rate, blastocyst formation and clinical pregnancy rate were not significantly different. A
total of 678 women who had IVF treatment were analysed (EN, n = 89; TF, n = 214; unexplained subfertility [UE], n = 375). The
mean age for each group were EN, 34.4 ± 3.3; TF, 33.5 ± 3.7 and UE, 34.6 ± 3.2, respectively. The number of mature follicles
(>14 mm) on the day of trigger injection was similar (P = 0.75) between all groups. The percentage of oocytes collected per
mature follicle was lower in endometriosis compared to other groups (P = 0.01; EN, 65 ± 23; TF, 76 ± 20; UE, 71 ± 24). Higher
percentages of embryos fail to achieve the 8-cell stage in EN compared to control groups (P = 0.02; EN, 4.0 ± 1.6 TF, 1.2 ± 0.4; UE,
1.5 ± 0.4). Percentages of embryos at all grades (Grade 1–4) per woman were similar between the comparison groups (P > 0.05).
EN did not impair (P > 0.05) blastocyst development or the development of fully expanded hatching blastocysts (FEHB).

Conclusions: EN may impair early embryo development through compromised oocyte quality, but not later embryo development
or pregnancy rate. This study finds women with endometriosis have a lower number of oocytes per total number of follicles. The
presence of endometriosis is associated with a higher rate of early embryo arrest, which implicates poor oocyte quality. However,
endometriosis has no effect on the embryo quality beyond the 8-cell stage of embryo development.

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Identifiers

ORCID for Ying Cheong: orcid.org/0000-0001-7687-4597

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