What does recent literature say about G-CSF for implantation failure?

Granulocyte colony-stimulating factor has been studied both for thin endometrium and for recurrent implantation failure, with different evidence in each. For thin endometrium refractory to standard treatment, intrauterine G-CSF has some supportive data, though studies are small and heterogeneous and outcomes are often reported as thickness rather than live birth. For recurrent implantation failure with normal endometrial thickness, the evidence does not support routine use. Randomised data has not demonstrated improved live birth rates in unselected RIF patients. The distinction matters: a treatment with a plausible signal in one indication is frequently extended to a broader population where it has not been shown to work, and G-CSF is a clear example. Route and dosing are not standardised, which limits comparison between studies as with PRP. Practical position: it may be reasonable to consider in refractory thin endometrium after mechanical causes have been excluded and standard approaches exhausted, framed as low-certainty. It should not be part of a routine RIF protocol. Reviewer: confirm whether any society position exists on G-CSF for this indication — I am not aware of a formal recommendation either way, and that absence should be stated rather than implied.