Endometrial pattern but not endometrial thickness affects implantation rates in euploid embryo transfers

Endometrial pattern, but not thickness, on trigger day affected a patient’s chance of achieving a pregnancy. The pattern or thickness at embryo transfer had no effect.

Julian A. Gingold, M.D., Ph.D., Joseph A. Lee, B.A., Jorge Rodriguez-Purata, M.D., Michael C. Whitehouse, B.A., Benjamin Sandler, M.D., Lawrence Grunfeld, M.D., Tanmoy Mukherjee, M.D., Alan B. Copperman, M.D.

Volume 104, Issue 3, Pages 620-628


To evaluate the relationship of endometrial thickness (EnT) and endometrial pattern (EnP) to euploid embryo transfer (ET) outcomes.

Retrospective cohort.

Private academic clinic.

Patients (n = 277; age 36.1 ± 4.0 years) whose embryos (n = 476) underwent aneuploidy screening with fresh (n = 176) or frozen (n = 180) ET from July 2010 to March 2014.

The EnT and EnP were measured on trigger day and at ET. Patients were stratified by age and cycle type (fresh or frozen). Cycle data were combined at trigger day, but separated at ET day.

Main Outcome Measure(s):
Outcome measures were implantation rate, pregnancy rate, and clinical pregnancy rate. Analysis was conducted using χ2 analysis and Fisher’s exact test.

A total of 234 gestational sacs, 251 pregnancies, and 202 clinical pregnancies resulted from 356 cycles. The EnT (9.6 ± 1.8 mm; range: 5–15 mm) at trigger day (n = 241 cycles), as a continuous or categorical variable (≤8 vs. >8 mm), was not associated with implantation rate, pregnancy rate, or clinical pregnancy rate. The EnT at day of fresh ET (9.7 ± 2.2 mm; range: 4.4–17.9 mm) (n = 176 cycles) or frozen ET (9.1 ± 2.1 mm; range: 4.2–17.7 mm) (n = 180 cycles) was not associated with implantation rate, pregnancy rate, or clinical pregnancy rate. Type 3 EnP at trigger day was associated with increased serum progesterone at trigger and a decreased implantation rate, compared with type 2 EnP. The EnP at fresh or frozen ET was not associated with implantation rate, pregnancy rate, or clinical pregnancy rate.

Within the study population, EnT was not significantly associated with clinical outcomes of euploid ETs. A type 3 EnP at trigger day suggests a prematurely closed window of implantation.

  • jallmann

    At the time in the absence of PGS, EnT (endometrial thickness) was evaluated irrespective of embryo karyotype. The overwhelming journals reported that EnT (<7-8mm) has lower likelihood of implanation rate than normal EnT. Of course, a few journal argued against the negative effect of thin EnT (but it's not so many)

    However, this journal inserted one variable (embryo's karyotype) to show that enploidy embryo was not influenced by EnT, but by EnP (endometrial pattern).

    I can't get a full understanding from this journal. When every embryo was transferred without any information, EnT can be important. But EnT may not be important after PGS.

    The authors should make a comment about the value of EnT after PGS, which was not in this journal.

    • Julian

      Thank you for your thoughtful review. As you correctly stated, one of the main findings from our study is that in embryos already characterized by PGS, the variability in EnT across cycles does not appear to be associated with pregnancy rates.

      We can therefore speculate that efforts to optimize EnT, once it is already within the ~5-17 mm range observed in our study cohort, may not be improving pregnancy rates.

      However, it would be premature to weigh in on the “value of EnT after PGS” when the intervention (especially stimulation timing and dosage) in our own retrospective study depended on EnT. We intentionally excluded discussion of its value from our manuscript because this can only be addressed with a randomized controlled trial.


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