Except for urine test, there is a blood test that provides a safe answer to a possible pregnancy. And this test is also based on identifying the pregnancy hormone – hCG (human chorionic gonadotropin) – but in blood, not in urine.
After fertilization, the ovule will attach to the uterine lining – this time, the body will produce this specific hormone of pregnancy, pregnancy tests being based on its detection. Unlike the urine test – which can be done at home and which is easy to do and the results appear in a matter of minutes, the blood pregnancy test must be done only under the supervision of a physician.
The blood tests to detect pregnancy may only look for the existence of the pregnancy hormone in the blood – and therefore offer a simple answer – “yes” or “no”, or they measure the exact level of the pregnancy hormone – in this case, you will receive a much clearer answer and the approximate date of fertilization.
Why are blood tests useful:
- They are more reliable and more accurate than urine tests – blood allows an earlier detection of the pregnancy hormone, even a week after the sexual intercourse during which fertilization occurred (even before the date when menstruation should occur); a urine test does not provide such clear results- you have to wait at least 2 weeks after the sexual intercourse to have a safe result – sometimes even 3 weeks (and about 5 days after the absence of menstruation). The blood test is rarely incorrect – unlike urine tests that can have false results, especially if they are done too early.
• You can do a blood test just before the time when menstruation should occur (but 7-10 days after the sexual intercourse).
• Because the urine test can give a false result, if you performed two urine tests at home at the same time or after a few days (as recommended for safe results) and the results of the two tests are different, a blood test is the best option to get a correct answer.
• If the urine tests gave negative results, but a delay of the menstruation occurs, a blood test can be an alternative (if the result is still negative, you must check to see what causes the lack of menstruation).
• Once a urine test gives a positive result and you go to a medical consultation, the doctor may choose to perform a blood test to confirm it (hospitals and clinics generally use blood tests).
• Blood tests may be done several times in the first period of pregnancy – to track the level of pregnancy hormone that normally increases constantly; if the level does not increase as expected, this indicates a pregnancy problem.
• The blood test is done by specialized personnel – so there is no risk that it may have been used incorrectly!
• It can accurately measure the pregnancy hormone levels in the blood, which provides useful information for the doctor.
Why are blood pregnancy tests less often chosen:
• Convenience and privacy – you need to know if you are pregnant or not, but you probably want privacy as well and a blood test should be done in the doctor’s office; so many women prefer the urine test, being more comfortable (the biggest disadvantage of the test is that it can be used a long time after the sexual contact).
• An appointment is necessary – you cannot go directly and ask for a blood test.
• The discomfort of testing blood – in some people, the process is cumbersome and can cause mild dizziness.
• The blood tests cost more than the urine tests.
• The result take a long time- a few days pass until the results are ready (about 2 days – although some private clinics offer the results the same day), which is stressful and a great disadvantage for the woman who wants an answer.
The blood tests to detect pregnancy are indeed safer, especially those that measure the exact level of pregnancy hormone – their accuracy is 98-99%, even early in 7 days after the sexual contact.
Although you can read in the instructions that a urine test provides the same accuracy in the results, the situation is not exactly the same: a urine test can be used properly and can give reliable results only after 2 weeks since the sexual intercourse and after a week since missing menstruation (that means much later). In addition, recently it was estimated that approximately 6-7% of the negative results of the urine test at home are false!
However, you can be those of 1-2% – receive a false result for the blood test – either a false negative result caused by testing too early, or a false positive result, which can be caused by certain medical treatments.