Gary, DRE, ejaculation, cycling and stimulating the prostate are all activities some of us are advised to avoid before a PSA test. There are numerous papers on how long the PSA is elevated for.
My GP missed a raised PSA result of 6.9 , three years later my PSA level was 7.7 and I went through the usual diagnostic procedures. Around 4 months after any DREs and a trus biopsy my PSA was 10.
Thanks Chris