Are Home Pregnancy Tests Always Accurate?

Are Home Pregnancy Tests Always Accurate?

When you're trying to get pregnant, you want to know if your efforts worked as soon as possible. So, like millions of women, you go to the store for a home pregnancy test and find an entire aisle dedicated to the various brands and types. 

After reading the labels and trying to figure out which is “best,” you settle on one in your price range that promises to tell you — with nearly 100% accuracy — if you’re expecting. 

But can you trust the results?

Here, Dr. Joseph Goin at Calvary Urgent Care in Humble, Texas, provides some valuable insight about home pregnancy tests that may save you a good deal of frustration. 

How home pregnancy tests work

Home pregnancy tests check your urine for a hormone called human chorionic gonadotropin (hCG), which your body only produces when you’re pregnant. Once a fertilized egg implants itself into your uterus, hCG production begins, and doubles every two days. 

Whether you choose a home pregnancy test that you hold in your urine stream or dip in a cup of urine, nearly all tests from major manufacturers can detect hCG about a week after you’ve missed your period. Tests that claim they’re 99% accurate and can be taken a day after your missed period, are a bit misleading. Here’s why.

The problems with home pregnancy tests

For a home pregnancy test to confirm your pregnancy as early as the first or second day of your missed period, it would have to be sensitive enough to consistently detect 12.5 mIU/mL of hCG in your urine. There’s only one test on the market that has this level of sensitivity, and it’s about 95% accurate. Three other leading brands are only accurate about 80% of the time, and most others are only 16% accurate. 

Beyond the quality of the test you use, other variables come into play as well.

Other sources of hCG

If you’ve recently miscarried, given birth, or taken fertility drugs, there may be hCG in your system that’s not related to a current pregnancy.

Test taken too early

As we mentioned, some tests are more sensitive than others, so depending on the type you use, your results may not be accurate until at least a week after your missed period.

Diluted urine

Your home pregnancy test has the best chance of being accurate when you use it first thing in the morning. That’s the time when your urine is most highly concentrated. As you drink water and other liquids throughout the day, it dilutes your urine and decreases the accuracy of the test.

User error

If you don’t follow the test instructions exactly, your results may not be accurate. If you choose the type that uses a dipstick and a cup of urine, you must perform the test within 15 minutes of collecting your sample. 

If your test comes with a stick you insert into your urine stream, wait the allotted time before checking your results. If you check too early or too late, the results may be inaccurate.

False-positives

It’s possible to get a positive (pregnant) reading even if you’re not really pregnant. Although this is rare, it could happen if you have traces of blood in your urine, you’re taking medications that contain hCG, you take diuretics, or your pregnancy test has expired.

A false-positive may also occur if you’ve had a chemical pregnancy, meaning you were pregnant briefly, but the fertilized egg didn’t develop.

Is it better to get tested for pregnancy at a doctor’s office?

At Calvary Urgent Care, Dr. Goin uses two tests to check for pregnancy: urine test and blood test.

The urine test we use works the same as your home pregnancy test — it detects the presence of hCG in your urine. However, the chance of error is much lower, and we use the most sensitive tests available.

The blood test can detect pregnancy even earlier than a urine test. It not only lets us know if hCG is present, it lets us know how much is present. But these levels vary from woman to woman, so don’t worry if your hCG numbers are low in early pregnancy — anything above 25 mIU/mL is considered a positive pregnancy. 

And once your hCG hits 1,000-2,000 mIU/mL, a transvaginal ultrasound can detect the gestational sac and clear away any doubt you might have. 

The bottom line is: Some home pregnancy tests are extremely accurate when used correctly at the right time. We can confirm the results here at Calvary Urgent Care with a professionally administered urine test or a blood test (although you’ll have to wait for the results to come back from the lab).

To schedule a pregnancy test at Calvary Urgent Care, call us at 832-680-2273 for an appointment today. 

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