title: Temporary reappearance of sperm 12 months after vasectomy clearance.
abstract: OBJECTIVE
  To determine the incidence of positive semen analysis 12 months after vasectomy clearance.
  
  
  METHODS
  A prospective study was undertaken, starting in 1990, of men undergoing vasectomy. Azoospermia was confirmed by two successive semen analyses 16 weeks after vasectomy. One year later a further sample was analysed for the presence of sperm.
  
  
  RESULTS
  Of 1000 men who provided a sample for analysis, six men (0.6%) have had positive semen analyses 1 year after the initial tests showed azoospermia. In all six the sperm count was <10,000 per mL. Five of the six men produced a repeat sample 1 month later which, in all five cases, showed azoospermia. No pregnancies have been reported to date.
  
  
  CONCLUSIONS
  Transitory reappearance of sperm following successful vasectomy occurs in about 0.6% of men. This incidence is 18 times greater than the reported pregnancy rate following successful vasectomy.
authors.affiliation: Elliot-Smith Clinic, Churchill Hospital, Oxford, UK.
authors.forename: T S
authors.initials: TS
authors.lastname: O'Brien
authors.forename: D
authors.initials: D
authors.lastname: Cranston
authors.forename: P
authors.initials: P
authors.lastname: Ashwin
authors.forename: E
authors.initials: E
authors.lastname: Turner
authors.forename: I Z
authors.initials: IZ
authors.lastname: MacKenzie
authors.forename: J
authors.initials: J
authors.lastname: Guillebaud
mesh_terms: D006801:Humans; D008297:Male; D011184:Postoperative Period; D011446:Prospective Studies; D013076:Sperm Count; D013094:Spermatozoa; D014659:Vasectomy