Practice Tip: Saving embryos from exploded straws

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Published on: June 17, 2014

Anyone who has transferred a sizable amount of embryos has surely had one blow up.  In an attempt to salvage these situations, we employ the use of a test tube filled with flush media to thaw the straw in.  These polypropylene tubes are filled with flush media, placed in the thaw bath, and allowed to come to thaw temperature.  After an air thaw of 5 seconds, the straw is placed into the test tube and held there for 15 seconds.  If we do have a cotton plug blow out the bottom the tube is taking into the lab (or when on farm a frenzy of activity ensues as we hurry to set up the microscope in the back of the suburban) and the test tube is poured out and rinsed into a search dish.  Occasionally we will have to rinse the straw out to locate the embryo.  Once located the embryo is placed into holding media, washed, loaded, and transferred.  I would estimate that 75% of the time we do recover the embryo and salvage an otherwise unfortunate situation.  We have definitely seen pregnancies made with these embryos but I have not tracked the pregnancy rate to know if there is any negative effect.

If we do run into a mating or freeze code that we’ve had problems with (or we don’t have a microscope with us), we will try to prevent a blow up by removing the straw top during the air thaw.  This is accomplished by pinching around where the straw top is plugged into the straw (thus thawing it out with body heat) and removing the straw top before going into the test tube.

The ultimate way to prevent blown straws is to make sure they are loaded properly by completely saturating the cotton plug with cryoprotectant and having no air space at the other end between the cryoprotectant and the straw top, but that discussion is for another day.


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