How Accurate is Blood Testing for Pregnancy Confirmation?

Is blood testing for pregnancy accurate?

Hello Doctor, I started my period on August 23, with an average cycle of 29 days.
On September 4, I recorded a low basal body temperature and observed egg white cervical mucus.
I had intercourse on September 2, 4, 6, and 7.
On September 14, I took a home urine pregnancy test (using first morning urine), which showed a faint second line.
That same day, I went to a lab for a blood pregnancy test, and the report indicated a result of less than 1.2.
The lab technician said that a result greater than 5.0 is required to confirm pregnancy, so they told me I am not pregnant.
However, on the morning of September 15, I took another urine test, and this time there was a second line, but it was fainter than the one I saw on September 14.
My question is, am I pregnant or is it too early to test? Or does the blood test result from September 14 already confirm that I am not pregnant? I really hope to have a baby.
Please help me with this question.
Thank you.

Xiao Wen, 30~39 year old female. Ask Date: 2015/09/15

Dr. Lü Lizheng reply Obstetrics and Gynecology

Generally speaking, blood test results should be more accurate than urine tests.
However, blood tests conducted at large hospitals are more reliable than those done at smaller laboratories.
Both urine tests showed two lines, which indicates a likely pregnancy, but the levels may be too low to show a strong reaction at this early stage.
It is recommended to take another test in a week for more certainty.
Sincerely, Dr.
Li-Cheng Lu, Taoyuan Hospital.

Reply Date: 2015/09/15

More Info

When it comes to pregnancy testing, both urine and blood tests are commonly used, but they differ in their accuracy and the timing of when they can reliably detect pregnancy. Based on the information provided, let's delve into the accuracy of blood testing for pregnancy confirmation and address your specific concerns.

Understanding Pregnancy Testing
1. Types of Tests:
- Urine Tests: These are typically home pregnancy tests that detect the presence of human chorionic gonadotropin (hCG) in urine. They are most effective when taken after a missed period, usually around two weeks after conception.

- Blood Tests: These are conducted in a medical setting and can detect lower levels of hCG compared to urine tests. Blood tests can confirm pregnancy as early as 6-8 days after conception.

2. Timing and Accuracy:
- Blood tests are generally more sensitive than urine tests. A quantitative blood test (beta-hCG) can measure the exact amount of hCG in your blood, providing a clearer picture of whether you are pregnant. A level of hCG greater than 5 mIU/mL is typically considered positive for pregnancy.

- In your case, the blood test result of less than 1.2 mIU/mL indicates that you are not pregnant at that time. However, it’s important to consider the timing of the test. If you tested too early, it’s possible that hCG levels had not yet risen sufficiently to be detected.

Your Specific Situation
Given your menstrual cycle and the timing of your sexual activity, here are some points to consider:
- Timing of Tests: You mentioned that you had sexual intercourse on September 2, 4, 6, and 7, and you tested your urine on September 14. Since implantation typically occurs about 6-10 days after conception, testing on September 14 may have been too early to yield accurate results, especially if implantation had not yet occurred.

- Urine Test Results: The faint line on your urine test on September 14 suggests that there may have been some hCG present, but the level was likely very low. The fact that you tested again on September 15 and saw a faint line again indicates that you might be in the early stages of pregnancy, but the levels of hCG are still low.

- Follow-Up Testing: Since your blood test on September 14 showed a negative result, it is advisable to wait a few days and then retest, either with a urine test or another blood test. If you are indeed pregnant, hCG levels should rise significantly within a few days.

Conclusion
In summary, while blood tests are more accurate and sensitive than urine tests, the timing of the test is crucial. Your blood test result suggests that you were not pregnant at that time, but it is possible that you could be in the very early stages of pregnancy, which may not have been detectable yet. I recommend waiting a few days and retesting to see if your hCG levels have increased. If you continue to have concerns or if your period does not arrive, it would be wise to consult with a healthcare provider for further evaluation and guidance.
Remember, early pregnancy can be tricky to confirm, and fluctuations in hCG levels can occur, so patience and follow-up testing are key.

Similar Q&A

Can Blood Tests Provide More Accurate Pregnancy Results?

It has been almost three months since my last sexual intercourse, and I have seen online that some people did not get a positive pregnancy test until four months later. Have you encountered such cases, doctor? Is blood testing a more accurate way to determine the result? Most art...

Dr. Cao Guotao reply Obstetrics and Gynecology
Hello, a pregnancy test should be taken at least 12 days after conception for accurate results. The chances of pregnancy are low. If menstruation has not occurred for three months, it is advisable to see a gynecologist. Wishing you good health.

Is Blood Pregnancy Test Accurate 20 Days After Intercourse?

If a blood test on day 13 after sexual intercourse was negative, and on day 19 you noticed blood-tinged discharge when wiping after using the restroom, is the blood test on day 20 reliable for pregnancy testing?

Dr. Cao Guotao reply Obstetrics and Gynecology
Hello, it's been over 12 days, so it's accurate. Wishing you good health.

Understanding Pregnancy Tests: Urine vs. Blood Accuracy and Timing

Doctor, is it true that blood tests for pregnancy are more accurate than urine tests? If urine tests are positive, will blood tests also be positive? What are the specific time points when the results from each test are 100% accurate? Please help clarify my doubts.

Dr. Lin Wenbin reply Obstetrics and Gynecology
Blood tests are more sensitive than urine tests. There is no such thing as a 100% accurate test; results must be interpreted in conjunction with clinical findings for accurate diagnosis.

When is Pregnancy Test Accuracy Guaranteed: Urine vs. Blood?

Doctor, could you please tell me at what time points urine and blood tests for pregnancy yield 100% accurate results? Thank you.

Dr. Lü Lizheng reply Obstetrics and Gynecology
The longer the time since conception, the greater the number of pregnancy tissue cells, which will produce more human chorionic gonadotropin (hCG). Therefore, both blood and urine tests will become more accurate. For a blood test, it should be detectable about fourteen days after...