What is the possibility of a man getting a woman pregnant after a vasectomy?

Depending on how long after the vasectomy you have intercourse, after he had he vasectomy they usually test his sperm on a regular basis until there are no sperm present. If he had his vasectomy months to years ago then no you cannot get pregnant. It is possible it has come undone or is leaking. Regular Dr checkups are a way to prevent that. Old vasectomys were a clip. The clip may not be pinching anymore. Sperm can last up to 20 ejaculations...or 3mths after vasectomy. Be careful. Yes, but the chances are very slim. Vasectomies are the most reliable method of family planning with a failure rate of less than 1 per thousand. The most common reasons for failure are a) that the man didn't wait long enough after the operation (usually 2-3 weeks or 20 ejaculations) before having sex, and b) that the vas deferens spontaneously reconnected. The chances of a failure after properly clearing and being tested at 3 months are put at about 1 in 4000, or 0.025%.