Microinjection of human oocytes: a technique for severe oligoasthenoteratozoospermia

To determine outcome after microinjection with very poor quality sperm and after failed fertilization. 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. All material was obtained from the National University Hospital. One hundred and thirty-one from group 1; 35 from group 2. Sperm was injected subzonally or directly into the ooplasm. Normal and abnormal fertilization and pregnancy. 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. Subzonal transfer may be a viable technique for patients with severe sperm problems.