While home pregnancy tests that detect hormonal changes from urine streams are usually correct, they are not 100% accurate. False positives, while rare, can occur for a number of reasons, including problems with the tests themselves and changes in the female body. If you suspect you are pregnant, learn about the most common causes of false positives and visit your local family medical practice to be sure.
Why False Positives Occur
1. Expired Test
The expiration date of your home pregnancy test has a huge influence on the result. The chemical that reacts to the pregnancy hormone human chorionic gonadotropin, or hCG, may not work correctly in an expired test, resulting in a false positive. This hormone is found in urine as well as blood.
2. Recent Miscarriage or Abortion
An implanted fertilized egg in the uterine wall causes the female body to secrete hCG. Levels of the pregnancy hormone remain elevated following an abortion or miscarriage for a period of up to 35 days. Taking a pregnancy test within this window will create a false positive result, especially if the miscarriage was “incomplete” and pregnancy tissue remains in your uterus, creating hCG.
3. Ectopic Pregnancy
Fertilized eggs do not always make it to the uterus. Some implant in a fallopian tube, resulting in an ectopic or tubal pregnancy. Women with misshapen, scarred, or inflamed fallopian tubes are most susceptible to ectopic pregnancies, as are those who have had numerous uterine infections. And while the embryo produces hCG in an ectopic pregnancy, it has no room to grow and is a medical emergency that can damage the reproductive organs.
Some prescription medications such as anticonvulsants and infertility drugs contain hCG ingredients that result in false positive pregnancy tests. This is why the gynecologists and obstetricians at your local family medical practice recommend waiting until your first missed period to take a test.
5. Waiting Too Long to Read the Test
Reading the pregnancy test within the suggested time frame helps prevent false positives. Waiting too long can cause urine to evaporate and make a faint second line appear. Whether your pregnancy test uses the line method or not, read the results as soon as possible.
If you believe you may be pregnant, get the accurate results you need from Superior Urgent Care. The family medical practice provides residents throughout Keller, TX, and the surrounding areas with a range of services, including DOT physicals and emergency care. Walk-ins are always welcome. Call (817) 576-4050 today to discuss your symptoms with a physician or visit the family medical practice online for a complete service list. See what patients are saying on Yelp.