If trace amounts of sperm are present, will i still need reverse vasectomy to get impregnate someone?

Seems odd: By your question, i assume you had a vasectomy, and still have trace amonts of sperm in your ejaculate, which would mean your vasectomy is not working. Sperm is microscopic and a drop of semen may have millions of sperm in it. I do not think a reverse procedure would be needed if truly you have sperm in your ejaculate. Discuss with your urologic surgeon.