Thin endometrial stripe does not affect likelihood of achieving pregnancy in clomiphene citrate intrauterine insemination cycles

This study did not find any significant correlation between preovulatory endometrial stripe thickness and likelihood of achieving pregnancy in clomiphene citrate/intrauterine insemination cycles.

Albert Asante, M.D., M.P.H., Charles C. Coddington, M.D., Louis Schenck, Elizabeth A. Stewart, M.D.

Volume 100, Issue 6, Pages 1610-1614.e1, December 2013


To determine whether there is a correlation between preovulatory endometrial stripe thickness (EST) and pregnancy rates in clomiphene citrate (CC)/IUI cycles.

Retrospective cohort.

Infertility clinic of an academic medical center.

A total of 262 patients completed 562 transvaginal ultrasound–monitored CC/IUI cycles from January 2005 through December 2012.

All patients received oral CC. In 362 of the cycles, a single dose of gonadotropin was administered on cycle day 9 (MinStim). A transvaginal ultrasound was performed on cycle day 10, 11, or 12.

Main Outcome Measure(s):
Pregnancy rate per initiated cycle.

A total of 91 pregnancies ensued, yielding a pregnancy rate of 16.2% per initiated cycle. Pregnancy rates did not vary with EST 9 mm (14.8%, 16.3%, and 19.0%, respectively). There was no significant difference in mean EST between stimulation types (6.8 mm for CC vs. 6.7 mm for MinStim). When conception and nonconception cycles were compared, no difference in mean EST (6.9 mm vs. 6.8 mm, respectively) was observed. Area under the receiver operating characteristic curve for the probability of pregnancy based on EST was 0.51.

Preovulatory EST had no significant correlation with pregnancy rates in CC/IUI cycles. The decision to switch from CC to another treatment strategy should be influenced by factors other than thin endometrial stripe.

  • Micah Hill

    Thank you Dr. Asante for the article. I had the same questions as Amanda. Also, you ran several different analyses and regression models, showing no effect of the stripe on outcomes. I was curious if you also ran any threshold analysis or less than efficiency curves at values less than 6mm to see if other very small values of thickness had negative effects.

  • Amanda N. Kallen

    Dr. Asante and colleagues have published a very interesting study on the effect of endometrial stripe measurements in CC cycles. It is mentioned in the discussion that their findings were contrary to two previously published studies. Could the authors speculate on whether the difference in cycle day of EST measurement (in this study versus prior studies) is contributing to the different findings, and why that might be so? Thanks again for the great work!

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