How to detect pregnancy using Pregnancy Test kits?

By | April 14, 2016

A pregnancy test attempts to determine whether a woman is pregnant. Markers that indicate pregnancy are found in urine and blood and pregnancy tests require sampling one of these substances to identify these markers. Human chorionic gonadotropin (hCG), is the earliest discovered markers and is yet one of the reliable markers to determine pregnancy.

Home pregnancy kits check for hCG marker in the urine flow and are thus called Urine Pregnancy Test (UPT) kits

When can I take a pregnancy test?

It depends on the pregnancy kit that you use. Some home pregnancy tests are more sensitive than others. The sensitivity of a pregnancy test is described on the packaging as mIU/ml (milli-International Unit per millilitre). Pregnancy tests range in sensitivity from 10mIU/ml to 40 mlU/ml. The lower the number, the more sensitive the test, and the earlier it can detect pregnancy. 

 

Most of the home testing kits will give you accurate results if you test from the day your period is due. Currently, the earliest pregnancy test kits can be taken from 5 days before your period is due however the accuracy is around ~60%.

Positive:

  • If two distinct color bands (pink/purple) appear, one in the test region (T), one in the control region (C) within 5 minutes
  • Positive indicates woman is “pregnant”, for further confirmation consult Gynaecologist

Negative:

  • If only one distinct color band (pink/purple) appears in the control region (C) within 5 minutes
  • Negative indicates that woman may not be Pregnant. If periods are further delayed repeat test after a week and consult Gynaecologist for confirmation.

Invalid:

  • If no distinct color band appear ,both in the test region (T) & in the control region (C) within 5 minutes, then the test is invalid. It is recommended in the case to repeat the test

How accurate are pregnancy kits?

Urine home pregnancy tests are about 95%-99% accurate.

In few cases, the result might be false positive. hCG may remain detectable for a few days to several days after delivery, abortion, or natural termination. Also, trophoblastic disease and certain non-trophoblastic neoplasms including testicular tumors, prostate cancer, breast cancer, and lung cancer, cause elevated levels of hCG. False negative results may occur when the hCG levels are below the sensitivity level of the test.

Pregnancy Test kits can give presumptive diagnosis only. Confirmed pregnancy diagnosis should only be made by a physician.

What if men take a UPT?

You will get a negative result. But if you get a positive, then it is a bad news for you. Presence of hCG in men, can be a possible reason for rare form of testicular cancer (choriocarcima).

— Dr. Ashok Khopode