Purity: Doubt Whether Wudu Has Become Void
Practical Laws of Islam as per the teachings of Ayatullah Sistani
Ruling 299:
If someone doubts whether his wuḍūʾ has become void or not, he must treat it as still being valid. However, if after urinating one does not perform istibrāʾ and performs wuḍūʾ, and after performing wuḍūʾ some fluid is discharged about which he does not know if it is urine or something else, his wuḍūʾ is void.
-Ayatullah Sistani, Practical Laws of Islam, Purification (Taharah)