How Accurate Are Pregnancy Tests? Results and Timing

Q: How Accurate Are Pregnancy Tests? Results and Timing

Hello： The accuracy of pregnancy tests is over 99%. <br>However, there is still a risk of inaccuracy if not used properly. <br>It is recommended to retest or consult a healthcare provider for examination. <br>Hualien Hospital, Ministry of Health and Welfare, cares about your heal

How accurate are pregnancy tests?

Hello, Doctor.
My girlfriend and I had sexual intercourse on February 20 without ejaculation.
Yesterday, on March 13 (about 21 days after the intercourse), I used a Mentholatum pregnancy test stick to check her morning urine, and the result showed one line.
If I use the pregnancy test again on March 16 (about 24 days after the intercourse) and it also shows one line, can we rule out the possibility of pregnancy? Thank you for your help.
🙏

Niming, 10~19 year old female. Ask Date: 2024/03/14

Dr. Lin Manying reply Obstetrics and Gynecology

Hello: The accuracy of pregnancy tests is over 99%.
However, there is still a risk of inaccuracy if not used properly.
It is recommended to retest or consult a healthcare provider for examination.
Hualien Hospital, Ministry of Health and Welfare, cares about your health.

Reply Date: 2024/03/14

More Info

When it comes to the accuracy of pregnancy tests, timing and method of testing play crucial roles. Pregnancy tests, whether they are urine tests or blood tests, detect the presence of human chorionic gonadotropin (hCG), a hormone produced shortly after a fertilized egg attaches to the uterine lining.
In your case, you had sexual intercourse on February 20 and tested for pregnancy on March 13, which is approximately 21 days post-intercourse. Generally, it is recommended to wait until at least the first day of your missed period to take a home pregnancy test for the most accurate results. However, since you tested 21 days after intercourse, you are within a reasonable timeframe for detecting pregnancy.

If you received a negative result (one line) on the test on March 13, it indicates that either you are not pregnant or that the levels of hCG are too low to be detected at that time. If you plan to test again on March 16 (24 days post-intercourse) and receive another negative result, it would further decrease the likelihood of pregnancy.
However, it is essential to consider a few factors:
1. Sensitivity of the Test: Different pregnancy tests have varying sensitivities. Most home pregnancy tests can detect hCG levels of 20-25 mIU/mL. If you are using a test with lower sensitivity, it might not detect pregnancy until hCG levels are higher.

2. Timing of Implantation: After fertilization, the embryo typically takes about 6-10 days to implant in the uterus. hCG production begins shortly after implantation. If implantation occurs later than expected, it may take longer for hCG levels to rise to detectable levels.

3. Urine Concentration: Testing with first-morning urine is recommended because it is usually more concentrated, which increases the chances of detecting hCG.

4. Possible Variability: Some women may experience irregular cycles or delayed ovulation, which can affect the timing of when a pregnancy test will be positive.

5. Follow-Up Testing: If you continue to have concerns about a possible pregnancy, consider retesting a few days later or consulting with a healthcare provider for a blood test, which can provide more definitive results.

In summary, if you test negative on March 16 after a negative test on March 13, it is likely that you are not pregnant. However, if you have any symptoms of pregnancy or if your period does not arrive as expected, it is advisable to consult with a healthcare professional for further evaluation. They can provide additional testing options and guidance based on your specific situation.

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