Is it necessary for a catheterized patient from whom something resembling urine was discharged during prayer to repeat it, or are there special rulings for him?

A catheterized patient who does not suffer from incontinence, if urine exits during prayer time, his ablution is nullified. If he is certain that urine exited during prayer, his prayer is invalid and must be repeated. However, if he doubts its exit during or after prayer, his prayer is not invalidated.