Test done during pregnancy

Common Tests During Pregnancy | Johns Hopkins Medicine

• Genetic Screening

• First Trimester

• Second Trimester

• Ultrasound

• Amniocentesis

• Chorionic Villus Sampling

• Fetal Monitoring

• Glucose

• Group B Strep Culture

Your health care provider may recommend a variety of screenings, tests and imaging techniques during your pregnancy. These tests are designed to provide information about the health of your baby and may help you optimize your child’s prenatal care and development.

Genetic Screening

Many genetic abnormalities can be diagnosed before birth. Your doctor or midwife may recommend genetic testing during pregnancy if you or your partner has a family history of genetic disorders. You may also choose to have genetic screening if you have had a fetus or baby with a genetic abnormality.

Examples of genetic disorders that can be diagnosed before birth include:

• Cystic fibrosis

• Duchenne muscular dystrophy

• Hemophilia A

• Polycystic kidney disease

• Sickle cell disease

• Tay-Sachs disease

• Thalassemia

The following screening methods are available during pregnancy:

• Alpha-fetoprotein (AFP) test or multiple marker test

• Amniocentesis

• Chorionic villus sampling

• Cell-free fetal DNA testing

• Percutaneous umbilical blood sampling (withdrawing a small sample of the fetal blood from the umbilical cord)

• Ultrasound scan

First Trimester Prenatal Screening Tests

First trimester screening is a combination of fetal ultrasound and maternal blood testing. This screening process can help determine the risk of the fetus having certain birth defects. Screening tests may be used alone or with other tests.

First trimester screening includes:

• Ultrasound for fetal nuchal translucency. Nuchal translucency screening uses an ultrasound to examine the area at the back of the fetal neck for increased fluid or thickening.

• Ultrasound for fetal nasal bone determination. The nasal bone may not be visualized in some babies with certain chromosome abnormalities, such as Down syndrome. This screen is performed using an ultrasound between 11 and 13 weeks gestation.

• Maternal serum (blood) tests. These blood tests measure two substances found in the blood of all pregnant women:

  • Pregnancy-associated plasma protein A. A protein produced by the placenta in early pregnancy. Abnormal levels are associated with an increased risk of chromosomal abnormality.

  • Human chorionic gonadotropin. A hormone produced by the placenta in early pregnancy. Abnormal levels are associated with an increased risk of chromosomal abnormality.

When used together as first trimester screening tests, nuchal translucency screening and maternal blood tests have a greater ability to determine if the fetus might have a birth defect, such as Down syndrome (trisomy 21) and trisomy 18.

If the results of these first trimester screening tests are abnormal, genetic counseling is recommended. Additional testing, such as chorionic villus sampling, amniocentesis, cell-free fetal DNA or other ultrasounds, may be needed for an accurate diagnosis.

Second Trimester Prenatal Screening Tests

Second trimester prenatal screening may include several blood tests called multiple markers. These markers provide information about your potential risk of having a baby with certain genetic conditions or birth defects. Screening is usually done by taking a sample of your blood between 15 and 20 weeks of pregnancy (16 to 18 weeks is ideal). The multiple markers include:

• AFP screening. Also called maternal serum AFP, this blood test measures the level of AFP in your blood during pregnancy. AFP is a protein normally produced by the fetal liver that is present in the fluid surrounding the fetus (amniotic fluid). It crosses the placenta and enters your blood. Abnormal levels of AFP may indicate:

  • A miscalculated due date, as the levels vary throughout pregnancy

  • Defects in the abdominal wall of the fetus

  • Down syndrome or other chromosomal abnormalities

  • Open neural tube defects, such as spina bifida

  • Twins (more than one fetus is producing the protein)

• Estriol. This is a hormone produced by the placenta. It can be measured in maternal blood or urine to be used to determine fetal health.

• Inhibin. This is a hormone produced by the placenta.

• Human chorionic gonadotropin. This is also a hormone produced by the placenta.

Abnormal test results of AFP and other markers may mean that additional testing is needed. An ultrasound is used to confirm the milestones of your pregnancy and to check the fetal spine and other body parts for defects. An amniocentesis may be needed for an accurate diagnosis.

Since multiple marker screening is not diagnostic, it is not 100 percent accurate. It helps determine who in the population should be offered additional testing during pregnancy. False-positive results may indicate a problem when the fetus is actually healthy. On the other hand, false-negative results indicate a normal result when the fetus actually does have a health problem.

When you have both first and second trimester screening tests performed, the ability of the tests to detect an abnormality is greater than using just one screening independently. Most cases of Down syndrome can be detected when both first and second trimester screenings are used.

Ultrasound

An ultrasound scan is a diagnostic technique that uses high-frequency sound waves to create an image of the internal organs. A screening ultrasound is sometimes done during the course of your pregnancy to check normal fetal growth and verify the due date.

When are ultrasounds performed during pregnancy?

Ultrasounds may be done at various times throughout pregnancy for several reasons:

First Trimester

• To establish the due date (this is the most accurate way of determining the due date)

• To determine the number of fetuses and identify placental structures

• To diagnose an ectopic pregnancy or miscarriage

• To examine the uterus and other pelvic anatomy

• To detect fetal abnormalities (in some cases)

Midtrimester (also called the 18- to 20-week scan)

• To confirm the due date (a due date set in the first trimester is rarely changed)

• To determine the number of fetuses and examine the placental structures

• To assist in prenatal tests, such as an amniocentesis

• To examine the fetal anatomy for abnormalities

• To check the amount of amniotic fluid

• To examine blood flow patterns

• To observe fetal behavior and activity

• To measure the length of the cervix

• To monitor fetal growth

Third Trimester

• To monitor fetal growth

• To check the amount of amniotic fluid

• To conduct the biophysical profile test

• To determine the position of the fetus

• To assess the placenta

How is an ultrasound scan performed?

Two types of ultrasounds can be performed during pregnancy:

• Abdominal ultrasound. In an abdominal ultrasound, gel is applied to your abdomen. The ultrasound transducer glides over the gel on the abdomen to create the image.

• Transvaginal ultrasound. In a transvaginal ultrasound, a smaller ultrasound transducer is inserted into your vagina and rests against the back of the vagina to create an image. A transvaginal ultrasound produces a sharper image than an abdominal ultrasound and is often used in early pregnancy.

Which ultrasound imaging techniques are available?

There are several types of ultrasound imaging techniques. As the most common type, the 2-D ultrasound provides a flat picture of one aspect of the baby.

If more information is needed, a 3-D ultrasound exam can be done. This technique, which provides a 3-D picture, requires a special machine and special training. The 3-D image allows the health care provider to see the width, height and depth of the images, which can be helpful during the diagnosis. The 3-D images can also be captured and saved for later review.

The latest technology is 4-D ultrasound, which allows the health care provider to visualize the unborn baby moving in real time. With 4-D imaging, a three-dimensional image is continuously updated, providing a “live action” view. These images often have a golden color, which helps show shadows and highlights.

Ultrasound images may be captured in still photographs or on video to document findings.

What are the risks and benefits of ultrasound imaging?

Fetal ultrasound has no known risks other than mild discomfort due to pressure from the transducer on your abdomen or in your vagina. No radiation is used during the procedure.

Transvaginal ultrasound requires covering the ultrasound transducer in a plastic or latex sheath, which may cause a reaction in women with a latex allergy.

Ultrasound imaging is constantly being improved and refined. As with any test, the results may not be completely accurate. However, an ultrasound can provide valuable information to parents and health care providers, helping them manage and care for the pregnancy and the baby. In addition, ultrasound imaging gives parents a unique opportunity to see their baby before birth, helping them to bond and establish an early relationship.

Fetal ultrasound is sometimes offered in nonmedical settings to provide keepsake images or videos for parents. While the ultrasound procedure itself is considered safe, it is possible that untrained personnel may miss an abnormality or give parents false assurances about their baby’s well-being. It is best to have an ultrasound performed by trained medical personnel who can correctly interpret the results. Talk with your doctor or midwife if you have questions.

Amniocentesis

An amniocentesis involves taking a small sample of the amniotic fluid that surrounds the fetus. It is used to diagnose chromosomal disorders and open neural tube defects, such as spina bifida. Testing is available for other genetic defects and disorders depending on your family history and the availability of lab testing at the time of the procedure.

Who is an ideal candidate for amniocentesis?

An amniocentesis is generally offered to women between the 15th and 20th week of pregnancy who have an increased risk of chromosomal abnormalities. Candidates include women who will be over age 35 at the time of delivery or those who have had an abnormal maternal serum screening test.

How is an amniocentesis performed?

An amniocentesis involves inserting a long, thin needle through your abdomen into the amniotic sac to withdraw a small sample of amniotic fluid. The amniotic fluid contains cells shed by the fetus, which contain genetic information. Although specific details of each procedure may vary, a typical amniocentesis follows this process:

• Your abdomen will be cleansed with an antiseptic.

• Your doctor may or may not give a local anesthetic to numb the skin.

• Your doctor will use ultrasound technology to help guide a hollow needle into the amniotic sac. He or she will withdraw a small sample of fluid for lab analysis.

You may feel some cramping during or after the amniocentesis. Strenuous activities should be avoided for 24 hours following the procedure.

Women who are pregnant with twins or other higher-order multiples need sampling from each amniotic sac to study each baby. Depending on the position of the baby and placenta, amount of fluid, and woman’s anatomy, sometimes the amniocentesis cannot be done. The fluid is then sent to a genetics lab so that the cells can grow and be analyzed. AFP is also measured to rule out an open neural tube defect. Results are usually available in about 10 days to two weeks, depending on the lab.

Chorionic Villus Sampling (CVS)?

CVS is a prenatal test that involves taking a sample of some of the placental tissue. This tissue contains the same genetic material as the fetus and can be tested for chromosomal abnormalities and some other genetic problems. Testing is available for other genetic defects and disorders, depending on your family history and the availability of lab testing at the time of the procedure. Unlike amniocentesis, CVS does not provide information on open neural tube defects. Therefore, women who undergo CVS also need a follow-up blood test between 16 and 18 weeks of pregnancy to screen for these defects.

How is CVS performed?

CVS may be offered to women with an increased risk of chromosomal abnormalities or who have a family history of a genetic defect that is testable from the placental tissue. CVS is usually performed between the 10th and 13th week of pregnancy. Although exact methods may vary, the procedure involves the following steps:

• Your doctor will insert a small tube (catheter) through your vagina and into your cervix.

• Using ultrasound technology, your doctor will guide the catheter into place near the placenta.

• Your doctor will remove some tissue using a syringe on the other end of the catheter.

Your doctor may also choose to perform a transabdominal CVS, which involves inserting a needle through your abdomen and into your uterus to sample the placental cells. You may feel some cramping during and after either type of CVS procedure. The tissue samples are sent to a genetic lab for growth and analysis. Results are usually available in about 10 days to two weeks, depending on the lab.

What if CVS is not possible?

Women with twins or other higher-order multiples usually need sampling from each placenta. However, because of the complexity of the procedure and the positioning of the placentas, CVS is not always feasible or successful with multiples.

Women who are not candidates for CVS or who did not get accurate results from the procedure may require a follow-up amniocentesis. An active vaginal infection, such as herpes or gonorrhea, will prohibit the procedure. In other cases, the doctor may take a sample that does not have enough tissue to grow in the lab, generating incomplete or inconclusive results.

Fetal Monitoring

During late pregnancy and labor, your doctor may want to monitor the fetal heart rate and other functions. Fetal heart rate monitoring is a method of checking the rate and rhythm of the fetal heartbeat. The average fetal heart rate is between 120 and 160 beats per minute. This rate may change as the fetus responds to conditions in the uterus. An abnormal fetal heart rate or pattern may mean that the fetus is not getting enough oxygen or indicate other problems. An abnormal pattern also may mean that an emergency cesarean delivery is needed.

How is fetal monitoring performed?

Using a fetoscope (a type of stethoscope) to listen to the fetal heartbeat is the most basic type of fetal heart rate monitoring. Another type of monitoring is performed with a hand-held Doppler device. This is often used during prenatal visits to count the fetal heart rate. During labor, continuous electronic fetal monitoring is often used. Although the specific details of each procedure may vary, standard electronic fetal monitoring follows this process:

• Gel is applied to your abdomen to act as a medium for the ultrasound transducer.

• The ultrasound transducer is attached to your abdomen with straps so it can transmit the fetal heartbeat to a recorder. The fetal heart rate is displayed on a screen and printed onto special paper.

• During contractions, an external tocodynamometer (a monitoring device that is placed over the top of the uterus with a belt) can record the pattern of contractions.

When is internal fetal monitoring needed?

On occasion, internal fetal monitoring is needed to provide a more accurate reading of the fetal heart rate. Your bag of waters (amniotic fluid) must be broken and your cervix must be partially dilated to use internal monitoring. Internal fetal monitoring involves inserting an electrode through the dilated cervix and attaching the electrode to the scalp of the fetus.

Glucose Testing

Glucose testing is used to measure the level of sugar in your blood.

A glucose challenge test is usually conducted between 24 and 28 weeks of pregnancy. Abnormal glucose levels may indicate gestational diabetes.

What is involved in a glucose challenge test?

The initial one-hour test is a glucose challenge test. If the results are abnormal, a glucose tolerance test is needed.

How is a glucose tolerance test performed?

You may be asked to only drink water on the day the glucose tolerance test is given. Although the specific details of each procedure may vary, a typical glucose tolerance test includes the following steps:

• An initial fasting sample of blood will be drawn from your vein.

• You will be given a special glucose solution to drink.

• Blood will be drawn at various times over the course of several hours to measure the glucose levels in your body.

Group B Strep Culture

Group B streptococcus (GBS) is a type of bacteria found in the lower genital tract of about 20 percent of all women. While a GBS infection does not usually cause problems in women before pregnancy, it can cause serious illness in mothers during pregnancy. GBS may cause chorioamnionitis (a severe infection of the placental tissues) and postpartum infection. Urinary tract infections caused by GBS can lead to preterm labor and birth or pyelonephritis and sepsis.

GBS is the most common cause of life-threatening infections in newborns, including pneumonia and meningitis. Newborn babies contract the infection during pregnancy or from the mother’s genital tract during labor and delivery.

The Centers for Disease Control and Prevention recommends screening all pregnant women for vaginal and rectal GBS colonization between 35 and 37 weeks gestation. The treatment of mothers with certain risk factors or positive cultures is important to reduce the risk of transmission of GBS to the baby. Babies whose mothers receive antibiotic treatment for a positive GBS test are 20 times less likely to develop the disease than those without treatment.

Routine Tests During Pregnancy | ACOG

Acquired Immunodeficiency Syndrome (AIDS): A group of signs and symptoms, usually of severe infections, in a person who has human immunodeficiency virus (HIV).

Anemia: Abnormally low levels of red blood cells in the bloodstream. Most cases are caused by iron deficiency (lack of iron).

Antibiotics: Drugs that treat certain types of infections.

Antibodies: Proteins in the blood that the body makes in reaction to foreign substances, such as bacteria and viruses.

Bacteria: One-celled organisms that can cause infections in the human body.

Birth Defects: Physical problems that are present at birth.

Cells: The smallest units of structures in the body.

Cervix: The lower, narrow end of the uterus at the top of the vagina.

Chlamydia: A sexually transmitted infection caused by bacteria. This infection can lead to pelvic inflammatory disease and infertility.

Chromosomes: Structures that are located inside each cell in the body. They contain the genes that determine a person’s physical makeup.

Complications: Diseases or conditions that happen as a result of another disease or condition. An example is pneumonia that occurs as a result of the flu. A complication also can occur as a result of a condition, such as pregnancy. An example of a pregnancy complication is preterm labor.

Diabetes Mellitus: A condition in which the levels of sugar in the blood are too high.

Fetus: The stage of human development beyond 8 completed weeks after fertilization.

Gene: Segments of DNA that contain instructions for the development of a person’s physical traits and control of the processes in the body. The gene is the basic unit of heredity and can be passed from parent to child.

Genetic Counselor: A health care professional with special training in genetics who can provide expert advice about genetic disorders and prenatal testing.

Gestational Diabetes: Diabetes that arises during pregnancy.

Glucose: A sugar in the blood that is the body’s main source of fuel.

Gonorrhea: A sexually transmitted infection that can lead to pelvic inflammatory disease, infertility, and arthritis.

Group B Streptococcus (GBS): A type of bacteria that many people carry normally and can be passed to the fetus at the time of delivery. GBS can cause serious infection in some newborns. Antibiotics are given during labor to women who carry the bacteria to prevent newborn infection.

Hepatitis B: An infection caused by a virus that can be spread through blood, semen, or other body fluid infected with the virus.

Hepatitis C: An infection caused by a virus that can be spread through infected blood.

Human Immunodeficiency Virus (HIV): A virus that attacks certain cells of the body’s immune system. If left untreated, HIV can cause acquired immunodeficiency syndrome (AIDS).

Immune: Protected against infectious disease.

Intravenous (IV) Line: A tube inserted into a vein and used to deliver medication or fluids.

Measles–Mumps–Rubella (MMR) Vaccine: A shot given to protect against measles, mumps, and rubella. The shot contains live viruses that have been changed to not cause disease. The shot is not recommended for pregnant women.

Obstetrician–Gynecologist (Ob-Gyn): A doctor with special training and education in women’s health.

Preeclampsia: A disorder that can occur during pregnancy or after childbirth in which there is high blood pressure and other signs of organ injury. These signs include an abnormal amount of protein in the urine, a low number of platelets, abnormal kidney or liver function, pain over the upper abdomen, fluid in the lungs, or a severe headache or changes in vision.

Rectum: The last part of the digestive tract.

Rh Factor: A protein that can be found on the surface of red blood cells.

Rubella: A virus that can be passed to the fetus if a woman becomes infected during pregnancy. The virus can cause miscarriage or severe birth defects.

Sexually Transmitted Infections (STIs): Infections that are spread by sexual contact. Infections include chlamydia, gonorrhea, human papillomavirus (HPV), herpes, syphilis, and human immunodeficiency virus (HIV, the cause of acquired immunodeficiency syndrome [AIDS]).

Syphilis: A sexually transmitted infection (STI) that is caused by an organism called Treponema pallidum. This infection may cause major health problems or death in its later stages.

Trimester: A 3-month time in pregnancy. It can be first, second, or third.

Tuberculosis (TB): A disease that affects the lungs and other organs in the body. TB is caused by bacteria.

Urinary Tract Infection (UTI): An infection in any part of the urinary system, including the kidneys, bladder, or urethra.

Vaccine: A substance that helps the body fight disease. Vaccines are made from very small amounts of weak or dead agents that cause disease (bacteria, toxins, and viruses).

Vagina: A tube-like structure surrounded by muscles. The vagina leads from the uterus to the outside of the body.

When to do a pregnancy test? Maternity hospital Leleka | Blog

Pregnancy in the life of every woman is a significant event and most often unexpected.

But, even if the pregnancy came as a “surprise”, you must definitely confirm your suspicions or refute them. And you can do this with the help of an instant express pregnancy test, in a matter of seconds.

The most informative are digital and tablet tests (the strip is placed on a plastic device with two "windows"). However, strip tests remain the most popular, which means that the price of the test does not affect the result.

If there is any doubt after the test, you should make an appointment with a gynecologist.

How the pregnancy test works

Despite the whole range of pregnancy tests, the principle of action is the same for everyone - to determine the level of hCG (the first hormone of pregnancy) in the urine.

Pregnancy test procedure

Pregnancy test is performed no earlier than the first day of missed period or approximately 2 weeks after the expected day of conception. Until the zygote attaches to the wall of the uterus, hCG is not released, which means that before ten days of pregnancy, it is not advisable to carry out a test or any other tests.

At the beginning of the test, you should carefully study the instructions for its use. Although the principle of operation is always identical: one part of the test (paper) is immersed in a container with urine, the other (with a chemical indicator) determines the result in the form of red / blue stripes, the symbols “+” / “-” or the words “yes” / “no” ". The result is evaluated after the time specified in the instructions (from 1 to 5 minutes).

Sometimes there are mini-pipettes for metered distribution of urine in the tests, which are very convenient to use.

But putting the test under the urinary stream is not recommended, since this method can technically disrupt the express screening and give an error.

When to take a pregnancy test

In order not to be confused by the numbers, dates and know exactly when it is appropriate to take a pregnancy test, you need to keep a calendar, control your well-being and know the basic process of how the egg is fertilized .

In every woman with a regular monthly cycle, the egg goes through several physiological stages of development, one of which is called “ovulation”.

Ovulation is the process where a mature egg is released from the ovary into the fallopian tube to join the sperm. If there is no sperm in the tube, the egg dies and menstruation occurs.

If during ovulation the spermatozoa were inside the woman's genitals and conception did occur, the fertilized egg (zygote) begins to "move" into the uterine cavity, with the help of the ciliated epithelium and the muscles of the fallopian tube itself.

This whole process takes about 1 week.

After a fertilized egg enters the uterine cavity, it attaches there, hCG rises in the blood, cells divide and further development of the fetus occurs.

Some rapid tests can determine the presence of the hormone as early as the fourth day, but it is still better to check after at least 1.5 weeks. Then the level of the hormone becomes high enough to confidently determine the condition of the woman.

When is a pregnancy test false?

Two strips on the test do not always cause delight in women, since pregnancy is not a cherished dream for all women, for most it is a surprise.

However, if you really do not plan a child and your test suddenly becomes “striped”, do not rush to panic, since a result error is not ruled out here.

False-positive or false-negative responses can range from a technical failure of a screening test to the identification of serious gynecological pathologies.

As you can see, pregnancy is not the most “terrible” thing that a test can determine, so we once again emphasize the importance of a gynecological examination.

Be that as it may, a positive test result is only the first step towards determining pregnancy. The second step is a visit to the gynecologist, who must confirm / refute the information received. Since there are situations when express screening gives a false positive answer.

Main causes of a false positive result

A false positive result is a result that indicates the presence of pregnancy, in the absence of it.

Causes:

1. Incorrect express test.

Incorrect use of the test is the main cause of a false positive response. Therefore, you always need to read the instructions and follow the specified algorithm of actions. The evaluation of the result should be carried out strictly within the specified time range, from 3 to 10 minutes. After this period, a weak second strip may appear on the test (due to evaporation of urine), and the woman will perceive the result as a pregnancy.

2. Marriage.

A defective test is a very rare occurrence, but no one is immune from such a situation. Knowing this, women buy several tests from different brands and thus the problem is leveled.

3. Postpartum period.

Pregnancy test remains positive throughout pregnancy and 3-4 weeks after delivery. Therefore, if the test after the recent birth of a child shows a positive answer, and you are not planning children of the same age, you should not worry. However, you still need to check with your doctor about the absence of pregnancy.

4. Miscarriage, abortion.

After a miscarriage, miscarriage or medical abortion, the level of hCG cannot immediately decrease, it takes time. And, as a rule, this process takes from 2 to 4 weeks. Therefore, doing a pregnancy test during this period simply does not make sense, since the result will be false positive.

5. Preparation for IVF.

Some women dream of pregnancy so much that they take tests even when they don't have to. As, for example, when preparing for IVF.

During this period, ovulation is stimulated with hormonal preparations, which also increase the level of hCG, although there is no pregnancy itself yet. Therefore, a pregnancy test done during this period can misinform a woman.

6. Oncopathology.

Sometimes a positive pregnancy test, in its absence, indicates serious pathological processes that increase the level of hCG. These are ovarian tumors, lung, brain, breast or stomach cancer.

Main causes of a false negative test

A false negative is a result that indicates no pregnancy, if any.

Causes:

1. Fertilization occurred before the start of menstruation, and the level of hCG did not have time to rise to the desired concentration.
2. There is a threat of miscarriage.
3. A woman is taking diuretics (diuretics).
4. Technical damage to the test.

If a pregnancy test shows a negative result, but the woman has specific pregnancy symptoms (morning sickness, dizziness, frequent urination, pain in the lower abdomen and chest), you need to see a doctor.

What to do if in doubt?

There are situations that make a woman doubt the correctness of a pregnancy test. For example, different tests give different results, spotting is present (similar to menstruation), screening gave a positive response, and there are no specific symptoms of pregnancy.

What to do in this case?

1. Do not look for the cause yourself, but go for a consultation with a gynecologist and approach the solution of the problem comprehensively.
2. Do not dispose of unwanted and unconfirmed pregnancies yourself.
3. Find the exact reason why the test showed a false positive result in the absence of pregnancy.

The Leleka maternity hospital is a modern medical institution where you will always receive specialized, highly qualified obstetric-gynecological and neonatological medical care at the level of world standards.

Only timely diagnosis and competent treatment will help preserve the reproductive health of a woman and there are no other options here.

About the pregnancy test

December 24, 2017

There are two lines on the test, but there is no pregnancy: does it happen?

Pregnancy can be both a long-awaited and a very unexpected event in the life of a woman or family. At that moment, when a woman begins to suspect about her “interesting position” or cannot connect the appearance of new characteristic symptoms with anything else, a pregnancy test comes to the rescue. This simple, but at the same time very convenient invention "works" quite accurately. The probability of an erroneous result with a timely test does not exceed 1%. Moreover, the test can be both false negative and false positive. Today we will talk about those situations when the test shows a positive answer, although the woman is not pregnant. Why does this sometimes happen?

How does a pregnancy test work?

To understand why a pregnancy test can give a false result, it is important to understand how it works. Before performing the test, read the instructions for use. The procedure is very simple: dip the test strip with a certain end into a container with urine or substitute it under a stream of urine, then evaluate the test after a specified time.

The appearance of two strips on the test will indicate a positive result, that is, an existing pregnancy. This is magic? Or how to explain such an amazing phenomenon that a narrow test strip can notify a future mother about an upcoming addition to the family earlier than a doctor?

What is hCG?

No, there is no magic in a pregnancy test. Simple chemistry. The test strip contains a chemical indicator that reacts with human chorionic gonadotropin (hCG). This is one of the earliest pregnancy hormones, which is secreted by the chorionic villi (future placenta). Its release begins from the moment the fetal egg attaches to the uterine wall, and continues throughout the pregnancy. It can be determined in the blood or urine of the expectant mother. The pregnancy test is based on the detection of hCG in the urine of the mother.

It is recommended that the test be performed no earlier than the first day of a missed period or approximately two weeks after the expected day of conception if the woman's cycle is irregular.

Why is a pregnancy test false positive?

Women react differently to the appearance of two strips on the test, because for someone pregnancy is a cherished dream, for someone it is an unpleasant surprise. In any case, a positive test result is only the first step in diagnosing pregnancy.

By the way, the test result is not always expressed as the number of strips. Sometimes the signs "+" or "─" appear, sometimes the words "pregnant" or "not pregnant", "Yes" or "No". This does not change the essence of the matter, because any pregnancy test only reflects the amount of hCG in the urine of the test.

However, it may happen that the test strip shows a positive result in the absence of pregnancy. Why? Let's take a look at the most common causes of a false positive pregnancy test.

Postpartum period

The level of hCG increases in the bloodstream and in the urine of the future mother from the first days of pregnancy, reaching its maximum in the third month of gestation (7-11 weeks). After reaching this period, the level of the hormone gradually decreases. However, the test remains positive throughout the pregnancy and even for some time after it ends (on average 3 weeks).

That is, there is no need to panic if the test shows two stripes after a recent birth. This does not mean that a woman will soon become a mother again. It just takes time for the hCG levels to drop. However, we must not forget about reliable contraception even in the first months after childbirth, if the family does not plan children of the same age.

Recent miscarriage or abortion

After a miscarriage (miscarriage, miscarriage) or abortion, the level of hCG also does not decrease immediately. This period can last from 9 to 35 days (about 3 weeks on average). Accordingly, a pregnancy test done in this time period may be positive if there is no embryo in the uterus at the time of the test. A positive test will be especially long if there are remnants of placental tissues in the uterine cavity.

If in doubt about the presence of pregnancy, a woman should donate blood for the level of hCG (this is not only a qualitative, but also a quantitative analysis) and / or do an ultrasound of the pelvic organs. This will make it possible to understand whether there is a pregnancy, or whether the test still reflects the presence of hCG from a pregnancy that was very recent.

Bladder drift

Women know very little or have never even heard of this disease, but obstetrician-gynecologists are very afraid of it. What is a blister? This is one of the most serious pathologies of pregnancy, in which the villi of the chorion (placenta) pathologically change. More often young women get sick. The reasons for this condition have not yet been fully established.

In the case of hydatidiform mole, bubble-like extensions form along the course of the chorionic villi. There are different forms of cystic drift. The normal development of the fetus with such a development of events in most cases is impossible, it dies. The disease itself is very serious, it can even threaten the life of the patient. Removing the mole is the only way to treat a woman.

Pregnancy test is always positive when a mole develops. Even the uterus grows in size because the chorionic villi grow like grapes. Of decisive importance in the diagnosis of hydatidiform mole is ultrasound examination of the uterus.

Chorionepithelioma (Choriocarcinoma)

This is a malignant tumor of the trophoblast (ie chorionic villus or placenta). Chorionepithelioma can be a consequence of cystic drift, as well as an independent disease. It happens both in pregnant women and in women in the postpartum period.

The tumor quickly metastasizes, forming foci in various internal organs. Since the tumor is based on trophoblast tissue, a large amount of hCG is produced, as a result of which the pregnancy test will be positive. The disease is very severe, the prognosis is serious.

Superovulation in preparation for IVF

Some women dream of having a baby so much that they take pregnancy tests even when it is not necessary, for example, in preparation for in vitro fertilization (IVF). During the period of taking drugs for superovulation, a large amount of hCG is produced in the ovaries, which will necessarily manifest itself as a positive test result, although pregnancy is still far away. Doctors should inform the patient in advance about this so that she does not make hasty conclusions that she was able to get pregnant on her own.

Tumors of the internal organs

All of the above reasons for a false positive pregnancy test are still related to pregnancy, even if it has recently ended or has not yet occurred. But it also happens that a positive test has nothing to do with pregnancy. We are talking about tumor processes in the internal organs, in which the tumor produces hCG. This happens with tumors of the ovaries, brain, cancer of the lungs, stomach, breast, etc.

As a rule, a woman learns about the presence of malignant tumors in other ways, and not through a positive pregnancy test. Still, a pregnancy test is usually done with a delay in menstruation, while a cycle failure in the presence of tumors is not at all necessary.

Technical violations during the test

It is very rare that a woman has a low-quality test in her hands, which gave a false positive result. However, knowing that this happens, many women deliberately do several pregnancy tests from different companies. Repeated test failure is unlikely. In addition, when conducting a test, it is necessary to strictly record the time allotted for interpreting the result. Usually it is 3-5 minutes.

By the way, it's not bad if another person (girlfriend, spouse) also evaluates the test. It happens that a woman simply imagines the desired stripe, while in fact it is not there.

What if I have doubts about a pregnancy test?

It happens that a woman doubts the correctness of the test. For example, the test shows a positive response, although there are no other signs of pregnancy. Or there are menstrual-like discharge, although the test speaks in favor of pregnancy. Or in a situation where two tests showed different results? What to do?

• First, don't try to find the truth yourself. The most correct thing is to consult an obstetrician-gynecologist.

  ---

  Learn more

  • 
    Future baby birthday calculator
  • 
    3 month old dark green poop
  • 
    Why do babies vomit after eating
  • 
    When do babies start to move in the womb
  • 
    Red splotches on back of neck
  • 
    Can people with spina bifida have kids
  • 
    Umbilical cord in the womb
  • 
    How to help with morning sickness when pregnant
  • 
    When do fetal movements become regular
  • 
    How to brush child teeth
  • 
    4Th month pregnancy bleeding