Painful ejaculations may be caused by a variety of conditions.
Causes of painful ejaculations:
(1) post-operative or post-traumatic (hernia repair, groin surgery, other)
(2) prostatitis
(3) prostatic cysts
(4) seminal vesicle calculi
(5) urethritis, typically from a sexually-transmitted disease
(6) tumor of or adjacent to the vas
Post-operative ejaculatory pain may be due to scarring around the vas. Nerve entrapment or damage following surgery using results in persistent pain.