Islamic Laws : Wudhu » Rules regarding WudhuAyatullah al Uzama Syed Ali al-Husaini Seestani
306. If a person doubts whether his Wudhu has become void, he should treat it as valid. But, if he did not perform Istibra (rule no. 73) after urinating, and performed Wudhu, and thereafter some fluid was discharged about which he was not sure whether it was urine or something else, his Wudhu will be void.
307. If a person doubts whether he has performed Wudhu or not, he should perform Wudhu.