title: The diagnosis of azoospermia depends on the force of centrifugation.
abstract: OBJECTIVE
  To determine the centrifugal force required to pellet sperm.
  
  
  METHODS
  Prospective, in vitro study.
  
  
  METHODS
  Tertiary referral center.
  
  
  METHODS
  Men undergoing semen processing or postvasectomy semen analyses.
  
  
  METHODS
  In Phase I, postvasectomy semen samples were centrifuged at 600 x g, and the pellets were examined. Supernatants from samples with no visible sperm underwent repeat centrifugation at 1,000 x g; the supernatants were removed and centrifuged at 3,000 x g. Pellets from both centrifugations were examined. Phase II examined nonazoospermic semen that was divided into 3 aliquots and centrifuged at 500, 1,000, and 3,000 x g. The supernatants were examined for the presence of sperm.
  
  
  METHODS
  Sperm presence in centrifuged pellets or seminal supernatant.
  
  
  RESULTS
  Phase I: After centrifugation at 1,000 x g and 3,000 x g, sperm were noted in 12% and 0% of samples, respectively. Phase II: Sperm were noted in the supernatant in 100% of samples subjected to 500 x g and 1,000 x g, and in 92% of samples subjected to 3,000 x g centrifugation.
  
  
  CONCLUSIONS
  If sperm are in the seminal plasma, they will also be present in the pellet following centrifugation at a force of 1,000 x g or greater. Semen samples that appear azoospermic upon initial wet mount microscopy should be centrifuged at a minimum of 1,000 x g for 15 minutes.
authors.affiliation: Division of Urology, Department of Surgery, Brown University Medical School, 2 Dudley Street, Providence, RI 02905, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Corea
authors.forename: Janice
authors.initials: J
authors.lastname: Campagnone
authors.forename: Mark
authors.initials: M
authors.lastname: Sigman
mesh_terms: D002498:Centrifugation / Q000379:methods*; D003937:Diagnosis, Differential; D006801:Humans; D066298:In Vitro Techniques; D008297:Male; D009845:Oligospermia / Q000175:diagnosis*; D011446:Prospective Studies; D013094:Spermatozoa / Q000166:cytology; D014659:Vasectomy