24 January 2023

When to do a pregnancy test after blastocyst transfer

When to do a pregnancy test after blastocyst transfer
By the Editorial Comitee IVI Blog

What’s the earliest you can take a pregnancy test? This is the first question many of our patients ask after blastocyst transfer, the culmination of the IVF treatment cycle. It’s completely understandable. After all, our patients have gone through a lot, emotionally and physically, to reach this stage. However, there are a few factors that make it more complicated for IVF patients than for other types of pregnancy.

In this article we will explain the reasons for this and why a pregnancy test after an IVF day 5 transfer, if taken too soon, could quite easily come up with a false result, whether that’s positive or negative. The same applies to a pregnancy test after an IVF frozen embryo transfer. The right time for when to do a pregnancy test after blastocyst transfer is when you can rely on the accuracy of the result. Let’s see what this means.

What is blastocyst transfer?

When you go through the process of In Vitro Fertilisation (IVF), blastocyst transfer is what feels like the end of the process. This isn’t the case, of course, since the end of the process is pregnancy. This does not actually take place until the embryo has implanted in the lining of your uterus. It doesn’t happen for a few days, whether you are about to be pregnant by natural means or with the assistance of IVF. These are the steps leading up to that exciting moment:

  • You make two visits to our clinic, during which we confirm a diagnosis. We agree a recommended treatment and establish a personalized protocol.
  • There follows a period of around 15 days duration. During this you receive ovarian stimulating hormonal treatment to encourage your ovaries to produce multiple eggs.
  • When these have reached an adequate number and matured sufficiently, you are given an injection of the hormone Human Chorionic Gonadotropin (hCG) which triggers final maturing of the eggs.
  • Exactly 36 hours later, egg retrieval takes place. The eggs are immediately fertilized in the laboratory, either through mixing with your partner’s or donor’s sperm or through Intracytoplasmic sperm injection (ICSI).
  • The resulting embryos are closely monitored during the following five days. During this time, all being well, they develop to the blastocyst stage. This is the time when our embryologists can select the healthiest embryo for transfer to your womb. Any unused healthy embryos can be frozen and stored for future use if necessary.

It is impossible for you, or our fertility specialists, to know whether the embryo transfer will result in pregnancy. The chemical changes that happen in your body if you have become pregnant are not detectable through a pregnancy test until around 11 days later. This is usually the time lapse, although since all cases are different, it may be slightly shorter or longer. Our IVF specialist will let you know the exact timing to take a blood test. If this is positive, an ultrasound scan follows 20 days later. At this point the pregnancy is visible and a heartbeat detectable.

When to do a pregnancy test

Home pregnancy tests work by registering the presence of hCG in the urine. Blood tests also detect the presence of this hormone, which the embryo produces shortly after implantation. Its levels rise steadily throughout the first trimester and fall off through the remaining six months.

There is a potential problem with taking a premature pregnancy test after blastocyst transfer. Some of the hormones which you were given before retrieval of the eggs could still be circulating in your body, both in your bloodstream and urine. So, if you take a pregnancy test too soon after blastocyst transfer, a positive result could merely be reflecting the presence of hCG remaining from your treatment.

Conversely, a pregnancy test taken too soon may return a false negative because the blastocyst can take a few days to implant and another few before the resulting levels of hCG are sufficient to be detectable. Blood tests are more accurate. This is why we always ask you to attend your fertility clinic for a Beta hCG test to confirm your pregnancy.

What about frozen embryo transfer?

We apply the same guidance and reasoning in the case of a pregnancy test after an IVF frozen embryo transfer. In this case, you will not have had the injection of hCG to trigger maturity and ovulation. Therefore, the likelihood of a false positive because the hormone is still circulating in your body is not so much of an issue. However, even though you have not been through the egg retrieval process and your embryos may have been in storage for a number of years, there is still a certain amount of medication involved in preparing your womb lining for reception of an embryo.

There is another factor to take into account in the case of frozen embryo transfer. This is that unlike fresh embryos which you could expect to implant within a day or two, it can take a few more days for frozen embryos, up to five days. Therefore in effect the same principles about pregnancy testing apply, though for slightly different reasons. The overall aim is to avoid the emotional distress caused by either a false positive or a false negative. You can be able to have complete confidence in the results.

Tips for getting through the two-week wait

We do understand how stressful it can be to have to wait those 11 days before having your blood test to confirm your pregnancy. It’s easier said than done to keep calm and carry on. We also know from experience that a false result can be even more distressing. So, stay as calm as you can, look after yourself. Remember that even if a single round of treatment turns out not to be successful, in most cases we can try again. In the meantime, why not browse our tips for dealing with IVF and the two-week wait?

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