What are the most effective treatments for refractory thin endometrium before embryo transfer?

Thin endometrium refractory to standard oestrogen is one of the more difficult problems in the field, and the honest position is that no intervention has strong evidence. First, exclude a mechanical cause. Intrauterine adhesions are the most important reversible contributor and require hysteroscopic assessment — treating pharmacologically without excluding Asherman syndrome is a common error. Approaches with some support but limited evidence: extended or higher-dose oestrogen, vaginal in addition to oral administration, vaginal sildenafil, pentoxifylline with vitamin E, and G-CSF. Effect sizes are modest and trials are small. Approaches that remain experimental: platelet-rich plasma and stem cell-based therapies. These are increasingly offered commercially. They should be presented as unproven rather than as advanced options, and ideally offered within research. An important reframing: endometrial thickness is a weak predictor of outcome in itself. ESHRE (2026) states that routine monitoring of endometrial thickness during stimulation is probably not recommended, with a good practice point suggesting a single measurement on the day of trigger or retrieval to counsel patients on potentially lower pregnancy chance. Pregnancies occur at thicknesses widely considered inadequate. Where the lining remains refractory, freeze-all with transfer in a subsequent optimised cycle, or eventually gestational surrogacy, are the realistic pathways.