- Semen culture (and not analysis, although the latter can be useful as well)
- PSA - signals if something is wrong with the prostate, which in young patients will most likely be prostatitis. In combination with proPSA and free PSA can be used to calculate a Prostate Health Index score.
- MRI - can provide additional data on the structure of the prostate. If you have insurance or can afford to pay for it, have it done. Besides increased volume, calculi are a common finding.
Of the above, the most important is the semen culture with susceptibility testing. GPs (family doctors), urologists, and infectious diseases doctors can order this test.