Late failure of vasectomy after two documented analyses showing azoospermic semen.

From April 1970 to December 1980, 14 047 men underwent vasectomy for sterilisation under local anaesthetic at this clinic. In each man sterility was confirmed by two analyses of semen showing azoospermia. Allowing for a minimum follow up of three years, the wives of six of these men subsequently became pregnant between 16 months and three years after vasectomy. Analyses of semen confirmed recanalisation of the vasa deferentia in all six men. Only five similar cases initially fulfilling the same criteria for sterility have previously been reported. Full account of the rare possibility of recanalisation should be taken both when couples are counselled preoperatively and when pregnancy occurs after the male partner has been confirmed to be sterile.