False Positive pregnancy occurs due to a variety of reasons. Many women search for what are the reasons for false-positive pregnancy tests. It is advised to consult a gynecologist for further confirmation of pregnancy if the pregnancy test results are positive.
What Is Pregnancy Test?
A pregnancy test is done to determine if women are pregnant or not. The pregnancy test can be done on blood or urine. The home pregnancy test can be done at home. For a pregnancy test through blood, you have to visit a clinical setting. Almost all pregnancy tests are done by determining the amount of Human Chorionic Gonadotrophic (hCG) hormone in blood or urine. When done appropriately, the pregnancy tests provide accurate results in the majority of the cases.
HCG hormone is secreted by the placental cells after implantation of the fetus. A small quantity of this hormone is also secreted by the colon, liver, and pituitary gland. This hormone stimulates the production of progesterone which plays an important role in maintaining pregnancy.
The hormone is a glycoprotein that comprises an alpha subunit and beta subunit. Intact hormone, alpha subunit and beta subunits are present in the blood during pregnancy. The kidney degrades the beta subunits to produce a core fragment.
Apart from the normal pregnancy, tests for hCG levels also provide important information related to aborted pregnancy, pathological pregnancy and other serious medical conditions including extra-uterine malignancies and choriocarcinoma.
What Is A False Positive Pregnancy Test?
The results of a pregnancy test can be divided into three important categories.
In this scenario, the pregnancy test gives accurate results. If there is a pregnancy, the test will give a positive result and if the test is negative, a negative result is given.
False Positive Results
In this scenario, the pregnancy test provides a positive result even when there is no pregnancy. This may be due to various factors.
False Negative Results
In this scenario, the pregnancy test gives a negative result even when the pregnancy is achieved. The primary reason for a false negative test is performing the test at a very early stage of pregnancy. In such a scenario, it is advised to retest for pregnancy after 7 days. A false-negative test may also cause women who have a higher level of hCG due to the association of antibody in the test kit with degraded hormonal fragments instead of the intact hormone. In such cases, the blood tests and ultrasound are done to confirm pregnancy.
What Are The Causes Of False-positive Pregnancy Test?
There are various causes of false-positive pregnancy results;
1. Protein or Blood In Urine
If the woman had blood or protein in the urine, the pregnancy kit may give a false-positive result. Blood may occur in urine due to various conditions such as cystitis. The presence of protein in the urine may be due to kidney damage.
2. Exogenous HCG
As the current pregnancy kits have high sensitivity for hCG hormone, any exogenous hCG administered to the patient may be detected by pregnancy kits. That may lead to false-positive results.
3. Ectopic Production Of HCG
HCG hormone is secreted by the embryo even when it is not present in the uterus. The condition in which an embryo is present at a place other than uterus such as the cervix or fallopian tube is termed as ectopic pregnancy. Ectopic pregnancy may also lead to a false positive test.
4. Underlying Medical Conditions
Various medical conditions such as extra-uterine malignancies, pituitary disorders, ovarian cysts, and choriocarcinoma may lead to false-positive results.
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5. Human Errors
Human errors also lead to a false positive test. The human errors include using an expired test kit or not performing and analyzing the test results as per instructions.
Various medications also interfere with the testing of pregnancy through pregnancy kits and may cause false-positive results.
7. Chemical Pregnancy
A chemical pregnancy occurs when the embryo is not able to implant. In such cases, the pregnancy test kit may give false-positive results.
8. Abortion or Miscarriage
Recent abortion or miscarriage may lead to false-positive results. This is due to the residual level of hCG present in the woman. It takes almost one to one-and-a-half months to have a normal level of hCG.
9. Evaporation Lines
Evaporation lines may also create confusion and lead to the assumption of a pregnancy that is not present. The best way to avoid such confusion is to analyze the results within the instructed time limit.
What Medications Can Cause A False Positive Pregnancy Test?
Many women query about what medications can cause a false positive pregnancy test.
Following are the medications that may lead to a false positive pregnancy test;
1. Neurological Drugs
Anti-psychotics, anti-convulsant, and anti-anxiety medications may cause a false positive test. Examples include diazepam, clozapine, phenobarbital, alprazolam, and chlorpromazine.
2. Anti-Parkinson’s Drugs
Anti-Parkinson’s drugs may also affect the results of pregnancy tests. These drugs include Bromocriptine.
Diuretics such as furosemide also affect pregnancy test results.
Rohit Jain is an IPR Specialist and Medical Content Writing Expert. For over a decade, he has written several articles in the areas of female infertility, Erectile dysfunction, hemangioma, cervical cancer, monoclonal gammopathy of undetermined significance, mononucleosis, mitral valve disorder, nerve sheath tumor, shin splints, mild cognitive impairment, cellulitis, brain metastases, atelectasis, MCAD deficiency, lymphoma, sepsis, cardiac rehabilitation and metabolic disorder among others.