Urine vs blood pregnancy tests

Introduction–
Pregnancy tests are done to determine the levels of HCG (human chorionic gonadotropin), a hormone that is secreted by the placenta during pregnancy.

HCG plays a very vital role in maintaining pregnancy. The urine pregnancy test (UPT) and the blood pregnancy tests both confirms that a woman is pregnant by detecting this hormone in a women’s urine or blood sample respectively.

Differences in technique–
The blood pregnancy test is done in a laboratory. In this test, a woman’s blood sample is collected by a lab technician and is analyzed, results of which usually takes a day and is not immediate.

UPT tests can be done at home or clinic by the woman herself by collecting her urine sample in a cup and then transferring few drops of urine in the test strip through a dropper that detects the hormone. The results are seen immediately within few seconds, two lines indicating, pregnancy positive and one line indicating pregnancy negative. This is a very simple and effective way to detect pregnancy.  In this test, there are antibodies present on the strip which become sensitive if the hormone is present in the urine sample.

Difference in Indications–
The detection of HCG hormone in ones blood sample confirms her pregnancy. This test is considered very accurate as opposed to the urine pregnancy test as it gives a quantitative result. In this test the concentration of the HCG hormone corresponding to the days of gestation (pregnancy) is detected and accurately known. It shows results as early as within a week of ovulation.  The levels of beta HCG gets doubled if the pregnancy is normally progressing .If the levels start falling down, in subsequent repeated tests, it indicates a missed abortion. A high level in early pregnancy indicates multiple fetus or twin pregnancy. This test is also useful for the doctors to rule out ectopic pregnancy, a condition where pregnancy continues outside the uterine cavity. If the level of HCG fails to rise in subsequent tests a risk of ectopic pregnancy is suspected.

An HCG below 5mIU/ml is considered negative for pregnancy.
An HCG level of 25mIU/ml and above is considered positive for pregnancy.
The urine pregnancy test is done when women suspects pregnancy after a missed period or unprotected intercourse. It is more like a screening test. The test can be effective only after two weeks of pregnancy. Its accuracy is 99%.

Summary
Blood pregnancy tests are more sensitive and help in detecting early pregnancy.
It confirms early pregnancy. Blood pregnancy tests are accurate. It helps in monitoring the progress of pregnancy for first 2 months. It is expensive, cannot be done at home. It doesn’t give immediate results. A false positive result is possible when a woman is on HCG injections for treatment of infertility.
Urine pregnancy test on other hand is a very easy, convenient, simple and a cheap way to check pregnancy. It can be done by the women themselves. It can give a false negative result if done early as the concentration of HCG will not be high enough to be present in the urine.

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