Is it obligatory to perform ghusl if one experiences a small amount of seminal fluid discharge (ma' al-ihtilam) where it is unknown whether it is semen (mani) or pre-seminal fluid (madhy)?

The small amount of water that exits is either semen (maniyy), in which case it necessitates ghusl (ritual bath), or pre-seminal fluid (madhiy), in which case it does not necessitate ghusl, and it is sufficient to purify what it touched by sprinkling water over it. If a Muslim is unsure of the nature of what exited, he may consider it semen and perform ghusl, or pre-seminal fluid and suffice with purifying it.