Fertility Testing

Does hCG (Human Chorionic Gonadotropin) Interfere with a UPT (Urine Pregnancy Test)?

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When you’re going through fertility treatments, a necessary step is giving yourself injections of various medications, at various times during the process. However, especially with hCG injections, timing is an important factor. You need to be patient and wait the recommended amount of time before taking a pregnancy test, because if you take a urine pregnancy test (UPT) too soon after an injection, you may get a skewed result.

Question:

I have heard that my hCG injection can interfere with UPT (urine pregnancy test) results. How long after I take my hCG injection can I take a UPT and expect accurate results?

Answer:

HCG products include Generic hCG, Novarel, Ovidrel and Pregnyl. These medications are used to induce the final maturation of the egg, so it can separate from the cells within the follicle and be released or ovulated approximately 24 to 36 hours after the injection.

In  IUI cycles, we use hCG products to reliably make ovulation occur on a given day, and schedule the insemination at the optimal time for conception.

In  IVF cycles, the hCG injection is given about 36 hours before the scheduled egg retrieval in order to optimize the timing of the egg retrieval, so as to retrieve the maximal number of eggs. If you attempt to retrieve eggs without using hCG, the eggs will be unable to be successfully extracted from the surrounding follicular fluid.

But what is hCG? It is Human Chorionic Gonadotropin, the same hormone that is produced during pregnancy. It is also the hormone detected in a pregnancy test, either using blood or urine.

However, hCG can also be used to mature eggs and induce ovulation, because it is very similar in structure and function to the hormone known as LH (luteinizing hormone). LH levels rise or “surge” just prior to ovulation and induce the ovulatory process. Giving hCG, therefore, causes the similar response by the ovary to induce ovulation.

Typically, it takes about 10 days for the drug hCG to clear from blood and urine. So, if you do an UPT too soon — 10 days or less after the hCG injection — you may get a false positive because you are detecting the medication that is still in your blood and urine, not the hCG that a pregnancy is making.

Your doctor or nurse will give you a date for a blood pregnancy test 12-14 days after your insemination/embryo transfer that will give accurate results. While the two-week wait can be stressful and testing at home can be tempting, I recommend against testing at home. If not timed properly, the results of your home pregnancy test may not be accurate, and could set you up for disappointment and confusion.

Dr. Friedenthal is a Fellow in Reproductive Endocrinology and Infertility at Reproductive Medicine Associates of New York. Dr. Friedenthal completed her residency training in Obstetrics and Gynecology at New York University and is the two-time award winner of the American Society for Reproductive Medicine’s Resident-In-Training Award.

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