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, sallallaahu ‘alayhi wa sallam, is His Slave and Messenger.
There is no doubt that the emission of urine drops invalidates Wudhoo’ (ablution) and accordingly the prayer as well. Any discharge emitted from the front and back passages, either urine, stool, wind, or any other emission, invalidates Wudhoo’, regardless of its amount.
Al-Mawsoo‘ah Al-Fiqhiyyah Al-Kuwaitiyyah (Kuwaiti Fiqh Encyclopedia) reads: “Muslim jurists unanimously agreed that the usual discharges that come out of the front and back passages such as urine, stool, semen, pre-ejaculatory fluid (Mathy), Wady (white penile secretion), wind, menstrual blood and lochia (post-partum blood or Nifaas) are all considered nullifiers of Wudhoo’, regardless of the amount of the emission. This is evidenced by the verse that reads (what means): {…or one of you comes from the place of relieving himself…} [Quran 4:43] This verse refers to the nullifiers of Wudhoo’ in general: urine, stool, or any other discharge (coming out of the back or front passages). Also, the Prophet, sallallaahu ‘alayhi wa sallam, said: “If any one of you feels something in his belly, and he is not sure whether anything came out of him or not, let him not leave the place of prayer unless he hears a sound or detects a smell...” [End of quote]
Hence, if you sneeze and believe with certainty that drops of urine came out, then you have to repeat the Wudhoo’. If these drops came out during prayer, then your prayer has been invalidated and you should repeat the Wudhoo’ and prayer.
Allaah Knows best.