Subendometrial platelet-rich plasma injection for refractory thin endometrium: a prospective pilot study

To evaluate the effectiveness of subendometrial autologous platelet-rich plasma (PRP) injections in improving endometrial thickness (EMT) and pregnancy outcomes in women with refractory thin endometrium. This prospective, single-arm, self-controlled trial was conducted at Nanjing Drum Tower Hospital between October 2023 and October 2024. A total of 21 women with refractory thin endometrium (EMT < 7 mm), including those with a history of multiple failed treatments (e.g., high-dose oestrogen, surgical adhesiolysis), were treated with subendometrial PRP injections. EMT and reproductive outcomes were assessed before and after PRP treatment. Subendometrial blood flow, intrauterine adhesion (IUA) status, and platelet count (PLT) were also evaluated. Data from pre- and posttreatment cycles were analysed using paired t-tests for continuous variables and Fisher's exact tests for categorical variables. Among the 21 enrolled patients, 18 completed the study. With respect to the baseline characteristics, the mean age of the patients was 36.7 years and the mean duration of infertility was 3.0 years (IQR 2.0-5.25). PRP treatment resulted in a significant increase in EMT from 6.55 mm (IQR 6.08-7.03) to 7.50 mm (IQR 6.78-8.10) (p < 0.001). In 12 patients (66.7%), the EMT reached ≥ 7 mm posttreatment. Despite these improvements, significant enhancement in EMT was not observed in 2 patients with severe adhesions. The clinical pregnancy rate (CPR) in frozen-thawed embryo transfer (FET) cycles was 44.4%, with 8 pregnancies (2 live births, 6 ongoing). A decrease in cancellation rates posttreatment (2.62 vs. 0.71, p = 0.016) was observed. The procedure was safe and well tolerated, with no serious adverse events reported. The PLT in PRP was 3.69 times higher than that in whole blood (p < 0.001), but there was no significant difference in serum oestradiol levels before and after PRP. Subendometrial PRP injections improved EMT and achieved a clinical pregnancy rate of 44.4% in this cohort. This approach may represent a promising alternative for patients with refractory thin endometrium unresponsive to conventional therapies, potentially enhancing fertility outcomes in ART cycles. As a small pilot study, these results are preliminary and should be interpreted with caution.