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8 results

  • 8 - Assisted reproduction – preparation and work-up of couples

  • Edited by Siladitya Bhattacharya, University of Aberdeen, Mark Hamilton
  • Book:
    Management of Infertility for the MRCOG and Beyond
    Published online:
    05 June 2014
    Print publication:
    30 January 2014, pp 85-96

  • Summary

    This chapter addresses issues related to patient selection and preparation prior to undergoing assisted reproductive technology (ART) techniques, and the role of regulatory control in ART and welfare of the child assessment. It discusses the special aspects of ART including gamete and embryo donation, pre-implantation genetic screening (PGS) and diagnosis (PGD) and fertility preservation. Before the processing of patient gametes or embryos, the couple should be screened for hepatitis B, hepatitis C and HIV to assess their risk of cross-contamination. In the UK, the regulatory control of ART lies with the Human Fertilisation and Embryology Authority (HFEA). The risk of implantation failure and pregnancy loss secondary to aneuploidy increases with advanced maternal age, particularly after the age of 35 years. Fertility preservation described in the chapter includes sperm cryopreservation, oocyte cryopreservation, and ovarian tissue cryopreservation.

  • 26 - Transplantation of whole frozen–thawed ovaries

  • from Section 5 - Cryopreservation of ovarian tissue
  • Edited by Ri-Cheng Chian, McGill University, Montréal, Patrick Quinn
  • Book:
    Fertility Cryopreservation
    Published online:
    06 July 2010
    Print publication:
    13 May 2010, pp 241-247

  • Summary

    Oocyte cryopreservation has long been envisaged as the ideal solution to the need to capitalize the reproductive potential derived from a cycle of ovarian stimulation, circumventing the ethical and legal problems posed by embryo cryopreservation. This chapter presents an overview of the current status of oocyte cryopreservation by slow-cooling methodology. It discusses recent advances, unresolved matters, and possible future developments. Cryoprotection may be achieved through the use of cryoprotective agents (CPAs), chemicals that interfere with the water-ice transition and interact with biomolecules, acting as water replacement. The use of alternative and less toxic CPAs is a potential approach in the development of more efficient slow-cooling protocols. Assessment of oocyte quality is one of the most crucial, intriguing and, yet, unresolved questions in vitro fertilization (IVF) and gamete biology. Ooplasmic vacuolization is frequently detected in mammalian oocytes treated with different cryopreservation protocols or exposed to CPA alone.

  • 24 - Transplantation of cryopreserved ovarian tissues

  • from Section 5 - Cryopreservation of ovarian tissue
  • Edited by Ri-Cheng Chian, McGill University, Montréal, Patrick Quinn
  • Book:
    Fertility Cryopreservation
    Published online:
    06 July 2010
    Print publication:
    13 May 2010, pp 218-232

  • Summary

    An effective oocyte cryopreservation program benefits infertile couples with moral or religious objections about cryopreservation of embryos. When considering all pregnancies and live births obtained from cryopreserved oocytes using the classic slow-freezing method, the survival rates averaged approximately 50%. The percentage of live births per thawed egg ranges from 1 to 10% using the classic slow-freezing protocols. Recently, improved survival and pregnancy rates have been reported using modified slow-freezing procedures, particularly increased sucrose concentration in the suspending solution, and the use of sodium-free freezing solutions. Several attempts have been made with immature human oocytes. Although survival rates seemed to be improved by the slow-freezing method, poor in vitro maturation (IVM) and fertilization are major problems associated with immature egg freezing. Rapid cooling (vitrification) of human oocytes has resulted in relatively higher survival rates. This study suggested that better results can be achieved by vitrifying mature oocytes rather than immature oocytes.

  • 20 - Egg freezing: the reality and practicality

  • from SECTION 5 - FUTURE FERTILITY INSURANCE: SCREENING, CRYOPRESERVATION OR EGG DONORS?
  • Edited by Susan Bewley, William Ledger, University of New South Wales, Sydney, Dimitrios Nikolaou
  • Book:
    Reproductive Ageing
    Published online:
    05 February 2014
    Print publication:
    01 June 2009, pp 211-226

  • Summary

    Cryopreservation protocols for isolated oocytes and complex ovarian tissues can be broadly classified as equilibrium freezing (slow-freezing protocols) or rapid freezing (vitrification protocols). Oocyte cryopreservation requires that the gametes tolerate three non-physiological conditions: exposure to molar concentrations of cryoprotective agents (CPAs); cooling to subzero temperatures and removal of or conversion of almost all of the liquid cell water into the solid state. Penetrating CPAs, such as glycerol, dimethyl sulphoxide (DMSO), ethylene glycol (EG) and 1,2-propanediol (PrOH), are all membrane-soluble and can pass into cells. Non-penetrating CPAs include sucrose, glucose, trehalose and polymers such as hydroxyethyl starch and polyvinyl pyrrolidone. The rate at which cells are cooled is fundamental to the success of cryopreservation. Consequently, at the time of writing, mature metaphase II (MII) oocyte cryopreservation remains a potential solution rather than a practical remedy for infertile women.

  • 50 - Oocyte and Embryo Freezing

  • from PART III - ASSISTED REPRODUCTION
  • Edited by Botros R. M. B. Rizk, University of South Alabama, Juan A. Garcia-Velasco, Hassan N. Sallam, Antonis Makrigiannakis, University of Crete
  • Book:
    Infertility and Assisted Reproduction
    Published online:
    04 August 2010
    Print publication:
    15 September 2008, pp 456-465

  • Summary

    Embryo cryopreservation is crucial for both the efficiency and the safety of assisted reproduction treatments. The potential risks of damage for cryopreserved-thawed embryos include exposure to medium biochemical contaminants, ice crystal formation within the embryo, toxic effect of cryoprotectants, damage during thawing process, physical damage during embryo manipulation, and DNA damage during embryo storage; but freezing itself cannot be considered a mutagenic procedure. Conventional embryo freezing concerns multicell embryos. Cryopreservation of early-stage embryos can be considered a valid alternative to conventional embryo cryopreservation. Cryopreservation of unfertilized oocytes presents more technical problems than early-stage embryo cryopreservation. The most alarming risk related with oocyte cryopreservation is aneuploidy in embryos conceived with this method. Children born from cryopreserved oocytes should be accurately monitored to ascertain the correct growth and development and to exclude possible genetic anomalies and malformations.