Hi Kayway, there used to be two ways of doing a vas, one they tied the ends off, and the other was to take an inch out of both of them , but some times they jus might reknit together, so thtas why way back in 1976 I had 3 tests, before they said off you go then.
Now in very rare cases a man can have a third tube, but this then should have shown in his tests and come back positive, but at the end of the day it just takes one rouge sperm left hanging around in his tubes, to come out late and bingo you now know the result.
Do hope this helps.
Good Luck
He should go to the doctor and get tested, to see if he is in fact fertile.
Other than total abstinence, no method of birth control is 100 percent effective. In rare cases, it is possible for sperm to find its way across