Endometrial thickness has been demonstrated in multiple studies to be a factor in assisted reproduction success. Although there are few data to indicate the efficacy of adjunct medical therapies, the use of these adjuvant therapies to enhance endometrial receptivity is increasing. It is important to emphasize that most of the published studies were performed in IVF patients where other factors such as oocyte age ultimately influence pregnancy outcomes. In an article that I published in the journal Reproductive BioMedicine Online in 2006, I used the donor oocyte model to evaluate the effect of adjuvant therapy on endometrial receptivity. Using the donor oocyte model, the effect of the ageing oocyte was controlled.
Donor oocyte patients were evaluated during a mock and subsequent donor cycle in order to see if adjuvant therapy improved endometrial thickness and receptivity. It was discovered that during the mock cycle 33.8% of the patients had endometrial widths suggestive of decreased receptivity based on an 8 mm endometrial width criteria.
In the data analysis, a ‘regression to the mean’ was witnessed, with the thickest endometrial linings decreasing and the thinnest linings increasing in width from the mock to the donor oocyte cycle regardless of adjuvant therapy. While the use of adjuvant therapy may not produce a thicker endometrium, our data suggested that assisted reproduction success rates were improved. We found that patients with initially insufficient endometrial response had improved pregnancy rates on adjuvant therapy.
There were 123 patients treated with adjuvant therapy in this analysis. The three different medical therapies used were low-dose (81 mg) aspirin (n = 80), vaginal estradiol (n = 27) and sildenfil (n = 16). All of these therapies had previously shown promise in assisted reproduction cycles.
Adjuvant therapy did improve outcome rates for the overall population in those patients with a peak mock endometrial thickness less than 8 mm. There was significant improvement in pregnancy rates provided by adjuvant therapy for patients who had evidence of endometrial insufficiency on ultrasound during the mock cycle. Pregnancy rate and live birth rate were significantly improved in the 123 patients who received adjuvant therapy compared with the 380 patients not receiving adjuvant therapy.
In summary, our data suggest that adjuvant therapy does not improve the ultrasonographic appearance of the endometrium but does improve pregnancy outcome. Based on these data, the use of adjuvant therapy does improve endometrial receptivity. However, the exact subset of patients who would benefit best from adjuvant therapy has yet to be determined. Likewise, the best adjuvant therapy for a specific patient is unknown. Often what separates a successful IVF cycle from a failed cycle, may be the ART (not the science) of selecting the best treatment for a specific patient.