All perfect praise be to AllahThe Lord of The Worlds, and may His peace and blessings be upon our Prophet Muhammad and upon all of his family and companions.
The coming out of semen obligates taking Ghusl (Ritual bath), even if the amount of the semen is small since the Hadiths commanding Ghusl in this case are unconditional. For example, Umm Salam (rad): Umm Sulaim, the wife Abu Talha said: “O Allah’s Messenger! Allah is not ashamed of the truth. Is a Ghusl (bath) compulsory for a woman when she has a sexual dream?” He (PBUH) replied: “Yes! When she sees signs of liquid” [Agreed upon].
Al-Imam Al-Nawawi (May Allah have mercy on him) said: "The jurists agreed that if semen comes out, then it is an obligation to perform Ghusl. According to the Shafie position, it doesn`t matter whether the semen came out by sexual intercourse, sexual dream, masturbation, looking, with desire or not, was of big or small amount; even a minute portion of a drop, while asleep or awake, a man or a woman, and sane or insane. All these, according to our position (Shafie) obligate performing Ghusl. However, Abu Hanifah, Malik and Ahmad said: "If semen comes out with strength and desire, then it obligates performing Ghusl, as indicated by the unconditional sound Hadiths." {Al-Majmou`, vol.2/pp.158}.
We have reviewed some Hanafie books, such as {Raad Al-Mohtaar, vol.1/pp.160-161}, but didn`t find any statement that links the obligation of performing Ghusl with discharging a big amount of semen. Maybe, the Fatwa in which the Hanafies excused performing Ghusl when having a tiny portion of impurity (Najasah) was misunderstood in this regard. This Fatwa doesn`t mean that the Hanafies don`t obligate taking Ghuslif semen comes out; rather, they don`t obligate washing off the semen itself from one`s clothes if its amount was less than a dirham. And Allah Knows Best.