Difference between Blood Test and Urine Test for Pregnancy
A pregnancy blood test measures for human chorionic gonadotropin (hCG) hormone in a woman's blood. The placenta creates the hCG hormones and secretes it into the system. The hormone can be detected in the blood within two weeks of fertilization. There are two types of blood tests for pregnancy and a health care professional performs both.
Urine tests for pregnancy are measuring for the hCG as well. HCG levels rise in a pregnant woman's body very quickly and urine pregnancy tests can normally pick up small amounts of the hormone by the second week of pregnancy or even earlier.
History of Blood Test and Urine Test for Pregnancy
Blood tests to detect pregnancy came about fairly recently in the overall history of pregnancy testing. It wasn't until the hCG hormone was identified that doctors began performing blood tests to measure the level of hormone in a woman's body.
Urine tests to detect pregnancy have been around since the days of the ancient Egyptians. The germination test was a popular test of the day. A woman would urinate on bags of grain. If the grain germinated the woman was pregnant. Studies conducted on this method in the 1960s showed the test was accurate at a rate of approximately 70%.
Accuracy Rates of Blood Test and Urine Test for Pregnancy
Modern day blood tests for pregnancy are very accurate. Some studies indicate that blood pregnancy tests are more accurate than urine tests. A qualitative blood test works like a urine test and only gives a yes or no answer about the hCG hormone being detected in the blood. A quantitative blood test measures the amount of hCG in the blood. Not only can it detect pregnancy more accurately, it can help determine the age of the baby.
A pregnancy test done with urine is just as accurate in most cases as a blood test. The only difference between a urine test and a quantitative blood test in terms of accuracy is that type of blood test can show an exact level of the hormone.
How and When to Take a Test
Blood tests are performed at your doctor's office or a clinic by a technician who is trained in phlebotomy. After the blood is drawn, it is labeled and sent to the lab. While all labs are different, most results come back within the day. Blood tests to detect pregnancy must be taken around a week after fertilization.
Urine test can be taken at your doctor's office or at home. Both types of urine tests are sensitive to the hCG hormone, but a woman who thinks she might be pregnant should wait until she misses her period to be certain the hormone will be picked up. Urine tests used within the first two weeks of fertilization can give a false positive, requiring the use of another test.
Similarities and Differences
- Blood tests and urine tests are both reliable methods of testing for pregnancy. Blood tests can be performed in a quantitative or qualitative style depending on the recommendation of the doctor.
- Urine tests routinely have a faster result shown and the urine test can be taken at home.
- Blood tests can only be carried out at your doctor's office or clinic.
- Urine tests for pregnancy are typically much less expensive than a doctor's visit and lab fees to have the blood test done, but there are factors that make a blood test necessary in some cases. If you are at risk for a problem pregnancy, your doctor might want to take quantitative blood tests at regular intervals to check the development of the baby during the first few weeks.