Pregnancy test kits: When to use, how they work, their accuracy and different types available
10. WHAT CAN CAUSE A FALSE POSITIVE RESULT ON A PREGNANCY TEST KIT?
If a pregnancy test is left for a few hours after taking it, it may show a false positive, which is why Dr Koh advises women to read the results within five to 10 minutes.
False positives may also show up if the pregnancy test is done soon after taking fertility medicines that contain beta hCG hormones, as part of an assisted reproductive technology cycle, she added.
In rare instances, ovarian tumours can secrete hCG in a woman’s body, resulting in a false positive.
As a few factors can result in a false positive, you can take the test over a few days or visit the clinic to get a blood test.
In rare cases, a woman in her late second or third trimester of pregnancy may have a negative urine pregnancy test.
Dr Koh explained that this is due to the hook effect, which arises due to the very high levels of hCG in the woman’s body. The antigens that urine pregnancy tests use are unable to detect the hCG hormone, giving a negative result.
11. WHAT HAPPENS IF A WOMAN USES AN EXPIRED PREGNANCY TEST KIT?
If the urine pregnancy test kit is expired, Dr Koh said that it is no longer accurate as the antibodies used to detect hCG levels begin to break down.
Consequently, it may show a false positive or false negative result, and such a result cannot be interpreted with any accuracy.
12. DO SEXUAL OR GYNAECOLOGICAL ISSUES SUCH AS SEXUALLY TRANSMITTED INFECTIONS, ENDOMETRIOSIS, POLYCYSTIC OVARY SYNDROME AFFECT THE RESULT OF A PREGNANCY TEST?
Sexual and gynaecological conditions don’t affect the results directly, although they can make it tricky to time when to take a pregnancy test, Dr Koh said.
This is because certain medications or treatments used to manage these conditions may affect the accuracy of pregnancy tests, she explained.
For example, polycystic ovary syndrome (PCOS) can cause a hormonal imbalance that might affect ovulation and menstrual cycles, potentially leading to irregular periods or difficulty in predicting ovulation.
