HPT After an hCG Trigger Shot

The Agonizing Two-Week Wait

Home pregnancy tests check for the presence of hCG in the urine. Once you receive the hCG trigger shot, you will test positive for hCG and will get a positive result on a pregnancy test. However, this will be a false positive, and doesn't mean you are pregnant.
You might hear your doctor talk about hCG's "half-life" and why you can't test right away. So, what is your doctor talking about? The half-life is the amount of time it takes for the medication to lose half of its activity. hCG has a half-life of about 24 to 29 hours, meaning that approximately every day, your hCG levels from the shot will drop in half.
How long you have to wait before it's "out of your system" varies, depending on the dosage of your trigger shot, the sensitivity of the pregnancy tests you use, and individual variations in how different women metabolize and excrete the drug. hCG could stay in one woman's body for more than 14 days but be gone after 7 days in another woman.

Is There a Better Way to Test?

A blood test called a quantitative hCG test will test the amount of hCG in your blood. hCG can be detected in the blood as early as eight to nine days after ovulation/fertilization (shortly after implantation).
At least two blood draws are required for this test to be accurate if you've had an hCG trigger. The first draw gets a baseline hCG level, and a second level is drawn two days later. If the hCG level increases, it can mean you are pregnant. If the level decreases, it could mean the test is detecting the hCG from the injection, and you may not be pregnant. Another blood draw can be done in two days to see if the hCG is still rising or still decreasing. If you're not into getting your blood drawn more than you have to (or if you just can't wait for blood tests), have no fear -- there is another way! A method called "testing out" can be used to see how long the hCG lasts in your body. Following the shot, use a home pregnancy test (HPT) every day (or twice daily, depending on how obsessed you are feeling at the moment) and watch as the lines get lighter. When the line is getting lighter, it means the hCG is leaving your system (there is less in your urine to test). When the line disappears or gets extremely faint, this tells you how long the hCG stays in your body. When the line comes back or starts getting darker again for a couple days in a row, you could be pregnant! At this point, you would want to call your doctor and make an appointment for a blood test to confirm the pregnancy. Several other factors need to be considered when testing out the shot. First, it is very important to use the same brand of HPT, preferably with the same lot numbers on the box. The lot number lets you know that they were all manufactured at the same time, leaving no room for changes. Each brand can differ in color and sensitivity. By using the same brand the whole time, you will be able to see the pattern better. Another factor is the concentration of your urine (how hydrated you are). Testing right away in the morning when your urine is typically the most concentrated is the best time. When we start talking about accuracy, we must keep in mind that HPTs aren't designed to be used in this manner; they're meant to provide a "yes or no" answer. When you get that positive test, try not to set your hopes too high (which is easier said than done), and make an appointment to get your blood drawn to confirm the pregnancy.
Last reviewed by: Arthur Schoenstadt, MD
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