Usually, doctors ask the patient to submit sperm samples two months post- vasectomy and another after the third month. When two consecutive samples are negative, the surgery is considered a success.

A study of 436 men who received vasectomies at the Cleveland Clinic showed that a quarter of the men didn’t submit a sperm sample at two months, and only 21% bothered to return for the second follow-up.

Three months after vasectomy, when just half of the total patients returned to give samples, 9% of the tests still contained sperm. The residual sperm were usually in low numbers and nonmotile (unable to move on their own).

Three men with sperm-free samples at two-month intervals showed a trace of them remaining at the three-month check. All three had sperm-free samples by four and five months following their vasectomy.

In patients who followed the instructions of their doctor for return checks, vasectomy was eventually judged successful in all but one. Those who didn’t return for testing could potentially still get their partner pregnant.

According to Dr. Nivedita Dhar, a researcher at the Cleveland Clinic, it is impossible to know if and when the sterilization surgery is successful if patients do not submit semen samples as directed.

It is important to note that vasectomy does not affect a man’s orgasm or ejaculation, and it doesn’t prevent sexually transmitted diseases.

Source:  WebMD