The objective of this study was to examine different clinical scenarios of in-vitro conception, viz. fertilization with conventional IVF, IVF with high insemination concentration (HIC) and intracytoplasmic sperm injection (ICSI), and assess on a sibling oocyte comparison the hypothesis that ICSI should be performed in all cases requiring in-vitro conception. ICSI with husband's spermatozoa had a higher incidence of fertilization as compared with IVF or IVF with HIC with donor spermatozoa (if previous failure of fertilization had occurred) for unexplained infertility. Similarly, ICSI with husband's spermatozoa had as high an incidence of fertilization as IVF with donor spermatozoa for patients with severe oligozoospermia, asthenozoospermia and/or teratozoospermia, even when the spermatozoa were not selected for their morphology. Two studies were performed to assess ICSI in potential oocyte-related failure of IVF, viz. when fertilization occurred in >50% of oocytes for one group of patients, and in <50% of oocytes in a second group. In both of these studies a significant proportion of the oocytes that failed to fertilize with conventional IVF eventually fertilized after ICSI. The overall conclusion was that ICSI as a first option offers a higher incidence of fertilization, maximizes the number of embryos and minimizes the risk of complete failure of fertilization for all cases requiring in-vitro conception. However, among other concerns, current knowledge of ICSI as an outcome procedure does not provide the confidence to use this process in all cases of IVF for the time being.

No abstract

During the past 3 years we have used direct injection of spermatozoa into the cytoplasm of the oocyte (DISCO) in an attempt to procure conception in vitro where subzonal insemination (SUZI) has failed. Acknowledging the paucity of information about this invasive procedure in humans, it was clearly the only alternative for some patients. A total of 58 patients (cycles) who had had previously failed SUZI elected for this approach. Sibling oocytes, where possible, were used as a comparison between DISCO, SUZI, partial zona dissection (PZD) and microdrop in-vitro fertilization (IVF). Fertilization and embryo transfer was achieved by 66% (n = 38) of patients. Patients with embryos derived solely from DISCO (n = 19) produced four clinical pregnancies (21%), four patients had embryo transfer from SUZI embryos only with no pregnancies, and 15 had embryo transfer from a mixture of SUZI and DISCO embryos, with one dizygotic twin pregnancy from a combined SUZI and DISCO embryo transfer (7%). Twins, one male and one female, have been delivered, there has been one miscarriage and two pregnancies are ongoing. Of the 627 oocytes, 251 were used for DISCO and 71 (28%) were fertilized, 296 were used for SUZI and 29 (10%) were fertilized; 70 were used for PZD, two (3%) were fertilized, and none of the 10 undergoing microdrop IVF were fertilized. Of the 58 patients (cycles) 31% (n = 19) had fertilization with DISCO only, 8% (n = 4) with SUZI only, 28% (n = 15) with both SUZI and DISCO, while only one (2%) had fertilization with PZD.(ABSTRACT TRUNCATED AT 250 WORDS)

Previous experiments have established a relationship between the morphological characteristics of human spermatozoa and their fertilizing potential in vitro. To assess further the efficiency of Percoll gradient centrifugation (PGC) as a method of sperm selection, we have examined morphological characteristics of spermatozoa from 86 teratozoospermic patients attending Nottingham University Research and Treatment Unit in Reproduction (NURTURE). Patients were divided into groups according to percentage normal morphology in the fresh sample: group A (n = 14), < 5% normal morphology; group B (n = 41), 5-14% normal morphology; and group C (n = 31), > 14% normal morphology. Morphology slides were prepared using Diff Quik staining techniques and evaluated by Kruger strict criteria, under oil immersion, at a magnification of x1000; specific defects, viz. head, neck, cytoplasmic droplets, tail, immature cells, were assessed individually. Following PGC, a sperm sample with enhanced morphology was recovered for group B (P < 0.01) and C (P < 0.005); however, for group A (very severe teratozoospermia) PGC did not select a sample with significantly improved morphological quality. Specific sperm defects affected by PGC were head, neck and immature cells. No significant difference was found for tail abnormalities or cytoplasmic fragments.

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The use of high insemination concentration (HIC) for in vitro fertilization (IVF) was compared with intracytoplasmic sperm injection (ICSI) in cases of male factor infertility. Sibling oocytes (n = 252) from 24 patients were used, 123 for HIC and 129 for ICSI. Although the incidence of fertilization was decreased with HIC (48% v. 61%), this treatment was nevertheless a viable option for many patients, especially when ICSI was not available. However, there was a higher incidence of cytoplasmic fragmentation of embryos after HIC compared with ICSI (36% v. 10%, P = 0.003) and the outcome was significantly affected by the severity of teratozoospermia. Using a cut-off of 5% normal forms, the incidence of fertilization with HIC for the group with < 5% normal forms was 37% compared with 72% for the group with > 5% normal forms; there was also a significant decrease in cleavage rate (P = 0.05) and the number of regular embryos (P = 0.005), and an increase in cytoplasmic fragmentation (P = 0.006) in patients with < 5% normal forms. No distinction was made between cases of teratozoospermia when ICSI was used. The present study confirms the value of HIC as a first line treatment for male infertility, as long as ICSI remains significantly more expensive and concerns on safety are mooted. However, the use of sibling oocytes for ICSI is recommended, especially in cases with < 5% normal sperm morphology.

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Micromanipulation technology entered the forum of human conception in vitro in the late 1980s. It was erroneously perceived as a new technology – a purely mechanical approach to bypass failures of conception in vitro, the aetiology of which were unknown. In fact, it is the modification of technology developed since the beginning of this century, and its logical utilization for conception in vitro, preconception (polar body) biopsy and preimplantation (blastomere and trophectoderm) biopsy in the realm of human infertility and genetic disorders.