All perfect praise be to Allah, the Lord of the worlds. I testify that there is none worthy of worship except Allah and that Muhammad is His slave and Messenger.
Ghusl is related to the ejaculation of semen; it is not required after masturbation without ejaculation, and it is not required due to feeling pleasure or arousal.
So, if there is no ejaculation of semen, then Ghusl is not obligatory, but if there is ejaculation, then Ghusl is obligatory due to the hadeeth that reads, "If you ejaculate, you must perform Ghusl." [Abu Daawood and An-Nasaa'i]; as well as the hadeeth that reads, "Water is from water (i.e. Ghusl is obligatory when there is ejaculation of semen).” [Muslim]
We have previously clarified in fatwa 84675 that it is forbidden to have a vasectomy (a permanent method of birth control).
Allah knows best.