EMMA SOPs - Washing embryos

 

Washing embryos before transfer to pseudopregnant recipients

 

To minimise the risk of transmitting pathogens or infectious agents during the embryo transfer process, we advise that the standard embryo washing procedure described by the International Embryo Transfer Society is followed. This procedure is described in detail in the IETS's Manual (3rd Edition), Chapter 6, 'Recommendations for the sanitary handling of in vivo-derived embryos.'

The essential elements of the IETS's embryo washing procedure are as follows:

  1. All embryos should have an intact zona pellucida before (and after) washing.
  2. Only embryos free of adherent debris should be taken through the washing procedure. Embryos may be cleaned before they are washed.
  3. Take the embryos through at least 10 separate wash dishes containing culture medium (e.g. M2). The wash dishes should contain 2-3ml of medium so that the each wash represents a >100 fold dilution of the previous wash.
  4. A new glass pipette should be used each time the embryos are moved from one dish to the next. The pipette should be filled with medium from the clean dish before aspirating the embryos and placing them in the clean dish.
  5. To minimise the risk of transferring pathogens to the next dish aspirate the embryos in the smallest amount of medium possible.
  6. This procedure can be used for either in vivo or in vitro-derived embryos.