Only one sperm test is necessary to clear the vast majority of men who have vasectomies of the chance of fathering children, according to Dutch researchers.
Their study involved 1,073 men who had undergone a vasectomy. They found 51 per cent of men had no active sperm three months after their operation and 45 per cent had fewer than 100,000 active sperm.
One year after the tests none of the men had fathered children. The authors said while two tests were usually required before menwere cleared their evidence suggested only one was needed in the majority of cases.