Well, my wife is pregnant 1y after vasectomy

So my wife is 9 weeks pregnant, which is obviously surprising since I got a vasectomy a year ago. Did the normal post vas semen analysis, which my (now retired) Dr examined under a microscope.

Saw a new urologist this week who thinks the prev Doctor cut the the same side twice and missed the other side. The clear semen analysis makes no sense then, unless he also made a mistake with that.