title: Microinjection of human oocytes: a technique for severe oligoasthenoteratozoospermia.
abstract: OBJECTIVE
  To determine outcome after microinjection with very poor quality sperm and after failed fertilization.
  
  
  METHODS
  Group 1, fresh oocytes from patients with very low sperm density and motility on the day of oocyte recovery; Group 2, 1-day-old oocytes that failed to fertilize.
  
  
  METHODS
  All material was obtained from the National University Hospital.
  
  
  METHODS
  One hundred and thirty-one from group 1; 35 from group 2.
  
  
  METHODS
  Sperm was injected subzonally or directly into the ooplasm.
  
  
  METHODS
  Normal and abnormal fertilization and pregnancy.
  
  
  RESULTS
  Subzonal transfer was done on 771 oocytes in group 1 and 188 oocytes in group 2. Multiple sperm were transferred [mean of 6.6 for group 1 and 7.3 for group 2]. Monospermic fertilization occurred in 16.6% and 14.9%, respectively. Polyspermy and parthenogenetic activation were low at 2.3% and 2.8%, respectively. Five pregnancies were obtained, but only one delivered. Ooplasmic injection (single sperm heads) was done in 38 oocytes from three patients with extremely severe oligozoospermia; only four two-pronuclear zygotes were obtained and replaced into two patients, without any resulting pregnancy.
  
  
  CONCLUSIONS
  Subzonal transfer may be a viable technique for patients with severe sperm problems.
authors.affiliation: Department of Obstetrics and Gynaecology, National University of Singapore.
authors.forename: S C
authors.initials: SC
authors.lastname: Ng
authors.forename: A
authors.initials: A
authors.lastname: Bongso
authors.forename: S S
authors.initials: SS
authors.lastname: Ratnam
mesh_terms: D005260:Female; D006801:Humans; D007317:Insemination, Artificial, Homologous / Q000379:methods*; D008297:Male; D008845:Microinjections; D009845:Oligospermia / Q000503:physiopathology / Q000628:therapy*; D009865:Oocytes; D011247:Pregnancy; D013076:Sperm Count; D013081:Sperm Motility