title: Sperm head's birefringence: a new criterion for sperm selection.
abstract: OBJECTIVE
  To investigate the characteristics of birefringence in human sperm heads and apply polarization microscopy for sperm selection at intracytoplasmic sperm injection (ICSI).
  
  
  METHODS
  Prospective randomized study.
  
  
  METHODS
  Reproductive Medicine Unit, Società Italiana Studi Medicina della Riproduzione, Bologna, Italy.
  
  
  METHODS
  A total of 112 male patients had birefringent sperm selected for ICSI (study group). The clinical outcome was compared with that obtained in 119 couples who underwent a conventional ICSI cycle (control group).
  
  
  METHODS
  The proportion of birefringent spermatozoa was evaluated before and after treatment in relation to the sperm sample quality. Embryo development and clinical outcome in the study group were compared with those in the controls.
  
  
  METHODS
  Proportion of birefringent sperm heads, rates of fertilization, cleavage, pregnancy, implantation, and ongoing implantation.
  
  
  RESULTS
  The proportion of birefringent spermatozoa was significantly higher in normospermic samples when compared with oligoasthenoteratospermic samples with no progressive motility and testicular sperm extraction samples. Although fertilization and cleavage rates did not differ between the study and control groups, in the most severe male factor condition (oligoasthenoteratospermic with no progressive motility and testicular sperm extraction), the rates of clinical pregnancy, ongoing pregnancy, and implantation were significantly higher in the study group versus the controls.
  
  
  CONCLUSIONS
  The analysis of birefringence in the sperm head could represent both a diagnostic tool and a novel method for sperm selection.
authors.affiliation: Società Italiana Studi di Medicina della Reproduzione (S.I.S.M.E.R.), Bologna, Italy. luca.gianaroli@sismer.it <luca.gianaroli@sismer.it>
authors.forename: Luca
authors.initials: L
authors.lastname: Gianaroli
authors.forename: M Cristina
authors.initials: MC
authors.lastname: Magli
authors.forename: Giulia
authors.initials: G
authors.lastname: Collodel
authors.forename: Elena
authors.initials: E
authors.lastname: Moretti
authors.forename: Anna P
authors.initials: AP
authors.lastname: Ferraretti
authors.forename: Baccio
authors.initials: B
authors.lastname: Baccetti
mesh_terms: D000328:Adult; D053627:Asthenozoospermia / Q000473:pathology / Q000628:therapy*; D001718:Birefringence; D002970:Cleavage Stage, Ovum; D010064:Embryo Implantation; D004624:Embryo Transfer; D005260:Female; D006801:Humans; D008297:Male; D008859:Microscopy, Polarization; D009845:Oligospermia / Q000473:pathology / Q000628:therapy*; D011247:Pregnancy; D018873:Pregnancy Rate; D011446:Prospective Studies; D013077:Sperm Head / Q000473:pathology*; D020554:Sperm Injections, Intracytoplasmic; D053625:Sperm Retrieval; D016896:Treatment Outcome