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

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

Design: Retrospective cohort.

Setting: Infertility clinic of an academic medical center.

Patient(s): A total of 262 patients completed 562 transvaginal ultrasound-monitored CC/IUI cycles from January 2005 through December 2012.

Intervention(s): 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.

Result(s): A total of 91 pregnancies ensued, yielding a pregnancy rate of 16.2% per initiated cycle. Pregnancy rates did not vary with EST <6 mm, 6-9 mm, and >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.

Conclusion(s): 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.