Beta hCG Pregnancy Test Results after IVF: Interpreting the Numbers
Note: 4/13/11 – Those of you that have had disappointments in your IVF treatment – as most have – are usually looking for answers as to why your treatment failed. Because in the best case scenario, only about half of IVF cycles result in a birth, IVF failure touches most patients at one time or another. For this reason, I am addressing my next series of blog posts to the questions that my patients most frequently ask after a failed cycle. Follow the link to view the first post on Questions After Failed IVF
Beta hCG Pregnancy Test Results After IVF
Each and every patient/couple undergoing IVF, makes a huge emotional, physical and financial investment. The fact that receiving the result of the beta hCG (human chorionic gonadotropin) pregnancy test represents the first decisive hurdle that must be confronted, makes this a very big deal!! The few days after the embryo transfer, waiting for this first outcome report from your fertility clinic is usually anxiety ridden and highly stressful. It is thus imperative that the Fertility Specialist and his/her staff deal delicately with the transfer of this critical information. Dropping the ball at this time would be unconscionable. The physician and staff must make themselves accessible to the patient/couple and communicate the results promptly, professionally and with sensitivity.
At least two quantitative beta hCG blood tests are done (2-4 days apart). The reporting of “beta” pregnancy test results is best deferred until after the 2nd blood test results are in. This is because a successful IVF outcome will (in younger women) result at best in 50-55% of cycles (with the notable exceptions of IVF using an egg donor and the transfer of genetically [CGH] tested “competent” embryos). Thus, it is important to counsel patients in advance of them undergoing beta hCG testing to have rational expectations. It is equally important to inform patients exactly how, when, and from whom they will receive the report of their beta hCG results, because they are about as likely to get “bad news” as they are likely to hear “good news”. Thus I usually advise my patients to “prepare for the worst while hoping for the best” and that in the event of a “negative” result they will have prompt access to me (or a designee) for counseling.
As soon as an embryo begins to implant and its root system (trophoblast) begins to invade the uterine lining (endometrium/decidua), it starts to release the “pregnancy hormone” human chorionic gonadotropin (hCG) into the recipient’s blood stream. About 12 days after egg retrieval, 9 days after a day-3 embryo transfer and 7 days after a blastocyst transfer, the woman should have a quantitative beta hCG blood pregnancy test performed. By that time almost all hCG injected to prepare the developing eggs for egg retrieval should have left the woman’s bloodstream. Thus the detection of >5 IU of hCG per ml of blood tested is an indication that the embryo has attempted/begun to implant. Since with third-party IVF (i.e. Ovum donation, gestational surrogacy, embryo adoption) or frozen embryo transfers, no hCG “trigger shot” is administered, the detection of any amount of hCG in the blood is regarded as significant.
Often times, an initial rise in hCG (between the 1st and 2nd test) will be slow (failure to double every 48 hours). When this happens, a 3rd and sometimes even a 4th hCG test should be done at 2-day intervals. A failure to double on the 3rd and/or 4th test is a poor prognostic sign. It usually indicates a failed or “dysfunctional” implantation but in some cases a progressively slow rising hCG level might point to a tubal (ectopic) pregnancy. Diagnosis requires additional serial blood hCG testing, ultrasound examinations and clinical follow-up to detect any symptoms or signs of an ectopic pregnancy.
In some cases the 1st beta hCG level starts high and then drops with the 2nd test, only to re-start doubling every 2 days thereafter. This sometimes suggests that there were initially more than one embryo implanting and that one of these subsequently succumbed and one survived to continue a healthy singleton pregnancy. It is customary for the IVF clinic staff to call the patient/couple (and when applicable, notify the referring physician) with the results of the hCG pregnancy test. Often times, the IVF doctor or nurse‑coordinator will work through the office of the referring physician to arrange for the all pregnancy tests to be done. If the patient/ couple prefers to make his/her/their own arrangements, the IVF program should provide them with detailed instructions as to how/when and where these tests should be done.
In the event that serial blood quantitative beta hCG pregnancy tests indicate that one or more embryos are likely to be implanting, some IVF physicians advocate daily injections of progesterone or the use of vaginal hormone suppositories for several weeks to support the implanting embryo(s). Others, including several SIRM physicians prefer to prescribe hCG injections three times a week for several weeks until the pregnancy can be defined by ultrasound. Some IVF centers do not prescribe any hormones at all, after the transfer.
At SIRM, patients undergoing frozen embryo transfer, egg donor, or surrogate cycles and who have blood hCG levels that show the appropriate 2-day doubling, will receive estradiol and progesterone injections and/or vaginally administered hormone suppositories, for 10 weeks following the diagnosis of implantation by blood pregnancy testing. A “clinical pregnancy” is defined as one where there is clear ultrasound evidence of an intrauterine gestation. Such confirmation is usually sought two to three weeks after the first “positive” beta hCG test.
A “chemical pregnancy” is one where in spite of the beta hCG test being “positive” it fails to progress to the point of ultrasound confirmation. Chemical pregnancies occur quite frequently following IVF. While they usually result from a chromosomally abnormal (aneuploid) embryo trying to implant, they can also be due to the uterine lining (for anatomical, immunologic or other reasons)being insufficiently receptive to allow healthy embryo implantation. Clearly, to the IVF patient, the diagnosis of a “chemical pregnancy” represents a severe disapointment. However its occurence provides clear evidence that at least one embryo reached the advanced preimplantation phase of development(the blastocyst stage), went on to “hatch” and attempted to implant. As such a “chemical pregnacy” can often be regarded as being a “dark cloud that has a silver lining”…. because it offers the hope of a successful clinical pregnancy in the future.
The chance of miscarriage progressively decreases from the point of diagnosing a viable clinical pregnancy (a conceptus that has a regular heartbeat of between 110 and 180 beats per minute). From this point on, the risk of miscarriage is usually less than 15% in women under 39 years of age and less than 35% in women in their early forties.
Conveying news of a “positive” beta hCG result is easy…. Everyone feels elated and vindicated. It is dealing with the unsuccessful case that offers the real challenge. In this regard, nothing is more important than establishing rational expectations from the get-go. In some cases (fortunately rarely), the patient/couple will crack under the emotional pressure and will require referral for counseling and in some cases psychiatric therapy.
I always counsel my patients that optimal care does not necessarily equate with an optimal outcome. There are too many variables that are outside of our control…especially the “divine” one. Having been involved in this field for about 30 years, it is my fervent belief that when it comes to IVF, the adage…”man proposes while G-d disposes” is always applicable!
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