All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger. We ask Allaah to exalt his mention as well as that of his family and all his companions.
Ablution becomes compulsory by passing urine but taking bath becomes compulsory by ejaculation. This ruling is true regardless of the quantity of urine or sperm.
For more details read the Fataawa: 84093and 82518.
Allaah knows best.