When an express pregnancy test is wrong, explained the gynecologist at Mechnikov University

All rapid tests, regardless of price and method of operation, are based on one principle - they determine the presence of human chorionic gonadotropin (hCG) in the urine. This is a hormone that begins to be produced in the female body 7-10 days after the fertilized egg begins to develop. It is believed that when pregnancy occurs, hCG can be detected already in the first days of a delayed menstrual cycle.

The tests contain special substances that detect the hormone and react to it by changing the color on the strip or by appearing on the screen of the electronic device: pregnon or non pregnon (“pregnant” or “not pregnant”).

Why can a negative answer be false?

If the concentration of gonadotropin is insufficient, the test result may be false negative. This can happen when conception occurred shortly before the start of menstruation, and hCG has not yet had time to accumulate in perceptible quantities. By the way, if the period is more than 12 weeks, the rapid test will also be useless: hCG ceases to be produced.

The test can be false negative in case of ectopic pregnancy and threat of miscarriage. With excessive fluid intake, the concentration of hCG in the urine may also decrease, which means the test result may be unreliable. Therefore, before the test, experts advise not to drink a lot of fluids and not to use diuretics. This is especially important in the short term, when a woman does the test in the first days after the delay. And it is best to determine the hormone level in the morning.

“Some tests say that the time of day at which it is carried out does not matter,” says Yulia Dolgo-Saburova. — As a rule, such tests are positioned as highly sensitive. But no matter what the instructions say, a few days after the delay, I would still recommend doing the test in the morning, since a noticeable amount of hCG appears in the urine throughout the day around the third week of embryo development.”

Magazine for pharmacy business professionals

An express test for diagnosing pregnancy is a seemingly simple thing.
But even it has nuances of use that a visitor may ask you about. Or maybe he won’t ask – simply because he doesn’t know what exactly to ask! Our expert: Inna Apolikhina

,
Doctor of Medical Sciences, Professor of the Department of Obstetrics, Gynecology, Perinatology and Reproductology FPPOV MMA named after. THEM. Sechenov, Federal State Institution NTsAGiP im. IN AND. Kulakova Rosmedtekhnologii

Design does not affect accuracy

A woman is wondering what to buy: a regular paper test strip or a beautiful plastic tablet with windows and a pipette, and asks you for advice.
Explain to her that the accuracy of all tests is the same - more than 99%. This means that it is with such a high probability that they detect the presence of the pregnancy hormone. However, make a reservation: if they are used correctly! It even makes sense to purchase 2-3 inexpensive test strips to double-check the result, rather than spend money on one expensive tablet. On the other hand, tests packaged in plastic are more pleasant and convenient to use. The kit comes with a pipette, with which you need to drop 4 drops of urine into a special window.

Everything has its time

We understand that you want to get tested for pregnancy as soon as... right away.
But there is no point in rushing. The test determines the presence of the pregnancy hormone, human chorionic gonadotropin (hCG), in the urine. And it cannot instantly appear in quantities sufficient to be “noticed” - 25 mIU/ml (international units in ml). The hormone is produced day after day from the moment the fertilized egg attaches to the wall of the uterus. For some women, pregnancy is detected on the 7th day after ovulation (which actually coincides with conception). But most women will have to wait.

NB!

HCG reaches such a level that the test reacts to it only after 10–14 days. This means that you need to be tested for pregnancy no earlier than the 1st day of your missed period.

The test may not detect pregnancy if there is a kidney pathology that prevents the release of the hCG hormone into the urine in normal quantities, or if the woman took a diuretic or drank a lot of liquid before testing.

ICS moment

How to read the result correctly? We are sure that not every customer knows all the nuances. The strip has two parts: the one closest to the tip is the zone that gives the answer ( t - test
), the farthest is the control zone (
c - control
), in which the strip should appear in any case - this is a sign of the system’s performance.

The t-zone contains antibodies to the hCG

. If it is present, they will react chemically with it and then the dye will be released in the form of a strip. By the way, if it is even barely noticeable, very pale, this is still considered a positive answer - pregnancy has occurred! If it is not present, the reaction does not occur, the dye is not released, and no signs of a second strip are observed.

The doctor's test does not cancel

It is important to understand that a home test will only show the presence of the pregnancy hormone.
But he will not answer how correctly the fertilized egg is attached, how the embryo develops, and indeed whether it is pregnancy. A positive result occurs in some cancers. And in case of an ectopic pregnancy, a rapid test can show both positive and negative results. NB!

You can't limit yourself to home checks. A visit to a gynecologist for a standard examination, tests and ultrasound is not cancelled!

A more sensitive method is laboratory determination of hCG in the blood. It is recommended to carry out from the 8th day after conception.

Can't be?

The test shows a positive result, but the woman is 100% sure that she is not pregnant.
This may happen if you completed a course of taking a fertility medication containing hCG less than 10 days ago. This also happens in the presence of a tumor disease. In this case, you should recommend consulting a doctor as soon as possible, but do not panic in advance: tumors are most often benign. However, it is not worth using an express pregnancy test for independent preliminary diagnosis. “ Imagine that you have questionable symptoms, and with the help of an express test you reject and exclude the presence of a tumor (one line), as a result, you calm down, do not consult a doctor and trigger a hidden disease,” says our expert. “This is one of the reasons why such tests are not officially recommended for diagnosing cancer. To make a diagnosis, a more accurate assessment of the changes occurring in the blood is required, and one study is not enough. Nevertheless, it is possible to detect some oncological problems using a rapid test. But identifying them in the early stages using a blood test is more reliable and effective (the hormone appears in the urine later than in the blood)

».

Instructions for using a rapid pregnancy test

1. Carry out the test in the morning - at this time the concentration of hCG is maximum. 2. Dip the strip into the cup exactly to the mark and for the time recommended by the manufacturer, otherwise you may ruin the test and the result will be unreliable. 3. If you have an irregular menstrual cycle, if the result is negative, it is recommended to repeat the test after 2-3 days.

Controversial situations

Two stripes that look like blurry spots - the answer may be false due to a low-quality, spoiled reagent.
Try another test. On the test, which half an hour ago showed that there was no pregnancy, there are now clearly 2 stripes! There is a rule: do not pay attention to the test result later than 10 minutes. The dye may be released spontaneously, and a second stripe will appear. If in doubt, it is better to repeat the experiment the next day, when the level of the pregnancy hormone in the body has increased a little more.

The test may not detect pregnancy if

- done too early - in the 1st week after conception - there is a kidney pathology that prevents the release of the hCG hormone into the urine in normal quantities - after taking a large amount of diuretics - you drank a lot of liquid
Olga Ageeva

Magazine "Russian Pharmacies" No. 20, 2011

Why can a positive answer be false?

In addition to false negative results, rapid pregnancy tests can also show false positive ones. This happens when taking drugs containing hCG, for example, ovulation-stimulating drugs Pregnil and Profazi. After completing treatment with these medications, high hCG levels may persist for up to two weeks. Therefore, you will have to wait with the test for this period. After miscarriages, abortions, or removal of an ectopic pregnancy, the hormone does not disappear immediately - it still remains in the body for some time, and tests can give false positive answers.

The test can also show pregnancy where there is none in various tumor processes.

How the pregnancy test works

Starting from the moment of fetal implantation, human chorionic gonadotropin levels increase rapidly. During the first 14 days, starting from the moment of implantation, its concentration doubles. In some places, from the 10th day after conception, the level of hCG in a woman’s blood becomes sufficient to determine the presence of pregnancy using a regular and compact rapid test, without even using the services of a laboratory. Upon contact with human chorionic gonadotropin, a dye begins to be released from the absorbent part of the test, which colors the second strip on the diagnostic field. The 1st lane is the control and is colored under the influence of liquid. The brightness of the test strip can be different, it directly depends on the concentration of the pregnancy hormone in the urine, in other words, in the very early stages it can be barely noticeable, but in the future it will become brighter.

What to do if your period is late?

If you experience regularly recurring delays in menstruation or the period of delay exceeds the maximum permissible physiological limits of five days, you should consult a doctor. After determining the reasons, the woman will be prescribed appropriate treatment. Most often, therapy is carried out using hormonal pills. However, under no circumstances should they be taken independently, without medical advice. This is extremely dangerous for a woman’s health and can disrupt the entire hormonal system, which means it can lead to serious health problems.

Among the most common hormonal drugs, doctors prescribe the following:

Duphaston. Used if a delay in the menstrual cycle is caused by insufficient levels of progesterone in the body. Only a doctor should adjust the dose based on the research conducted. If there is no pregnancy and the delay does not exceed 7 days, then postinor is prescribed for a period of 5 days. After this time, menstruation should begin two or three days later.
Postinor. It is a drug used for emergency contraception. This remedy is used if it is necessary to induce a menstrual cycle as quickly as possible. However, it is recommended only for regular menstruation, since its use can provoke cycle disorders, and if used very frequently, lead to infertility.
Pulsatilla. Another hormonal drug that can be prescribed for delayed menstruation. This is the safest remedy that does not lead to weight gain and does not affect the nervous system. However, it should not be taken by girls with irregular cycles.
Progesterone is an injectable hormone. Used to induce menstruation, dosage selection is carried out strictly individually. An increased intake of progesterone in the body can cause a lot of side effects, including excess hair growth, weight gain, and menstrual irregularities. More than 10 injections are never given. The effect is based on stimulating the work of the glands located in the mucous membrane of the uterus. The drug has a number of contraindications, including: uterine bleeding, liver failure, breast tumors, etc.
Non-ovlon, a drug that stimulates the onset of the menstrual cycle, can prevent acyclic bleeding. It contains estrogen and gestagen. Most often, if there is a delay, two tablets are prescribed every 12 hours. However, before using it, it is mandatory to consult a specialist, since the drug has side effects and can disrupt the functioning of the reproductive organs.
Utrozhestan. It is a drug that suppresses estrogen and stimulates the production of progesterone, which determines its therapeutic effect. In addition, it has a stimulating effect on the development of the endometrium. The drug can be administered vaginally, which is its undoubted advantage, however, this drug also has some contraindications.
Norkolut causes menstruation because it contains norethisterone, which is similar in action to the action of gestagens. And their lack often provokes failures in cycles and their delay. The course of treatment should not exceed five days; it is not used during pregnancy, as it risks miscarriage and bleeding. It has a large number of contraindications and side effects, so a preliminary consultation with a doctor is necessary.

Naturally, the use of hormonal drugs to induce menstruation is not a safe method. They must be taken correctly, as they can cause irreparable harm to health.

Examinations for delayed menstruation

To find out the reasons for the delay in menstruation, the following studies are prescribed:

Examination for sexually transmitted diseases (gonorrhea, chlamydia, trichomoniasis, mycoplasmosis, ureaplasmosis, etc.).
Ultrasound of the pelvic organs, thyroid gland and adrenal glands. This study is carried out to exclude pregnancy, tumors, gynecological and endocrine diseases.
Examination of the pituitary gland (radiography, magnetic resonance imaging, computed tomography, electroencephalography). Diseases of the pituitary gland are quite often the cause of delayed menstruation.
Hormonal studies. The levels of estrogen, progesterone, FSH, LH, PRL are determined, as well as thyroid and adrenal hormones.
Curettage of the inner layer of the uterus and its further histological examination. Curettage is performed from the cavity and canal of the cervix.

Reasons for delayed menstruation other than pregnancy

A delay in menstruation can be the result of physiological changes in the body, as well as be a manifestation of functional failures or diseases of both the genital and other organs (“extragenital pathology”).

Normally, menstruation does not occur during pregnancy. After childbirth, the mother’s cycle is also not restored immediately; this largely depends on whether the woman is lactating. In women without pregnancy, an increase in cycle length may be a manifestation of perimenopause (menopause). Irregularity of the cycle in girls after the start of menstruation is also considered normal, if it is not accompanied by other disorders.

Functional disorders that can provoke disruption of the menstrual cycle are stress, intense physical activity, rapid weight loss, previous infection or other acute disease, climate change.

Often, an irregular cycle with a delay in menstruation occurs in patients suffering from gynecological diseases, primarily polycystic ovary syndrome. In addition, such a symptom can accompany inflammatory diseases of the reproductive organs, occur after termination of pregnancy or diagnostic curettage, after hysteroscopy. Ovarian dysfunction may be caused by pathology of the pituitary gland and other organs that regulate a woman’s hormonal levels.

Of the somatic diseases accompanied by possible menstrual irregularities, it is worth noting obesity.

For pregnant

Modern obstetric practice involves the use of ultrasound diagnostics at least three times during the entire pregnancy. Should I be afraid of these procedures? No, it's not worth it. Ultrasound is completely safe for both the expectant mother’s body and her fetus.

Due to its high efficiency and lack of contraindications, this method has earned great popularity among doctors.

Positive result without symptoms

What to do if the coronavirus test is positive, but the disease is asymptomatic? In such situations, the patient should adhere to the following medical recommendations:

Call your local physician and report that the test result for COVID-19 is positive. The doctor will explain in detail what to do next, what measures to take to prevent the spread of infection to others.
Self-isolate for 14 days. If the general health is normal and the patient does not need hospitalization, he should self-isolate for two weeks - the period when the infection is most contagious and quickly spreads from the carrier to others. All this time, it is necessary to maintain contact with the attending physician, measure body temperature at least 2 times a day, ensure plenty of fluids, wet cleaning and ventilation of the room.
Do not contact others. If the patient lives with family members, use a medical mask during contact at home. All work and organizational issues can be resolved exclusively by telephone. If possible, stop using fans, air conditioners, etc.
Monitor your health carefully. While at home, the patient must carefully monitor his health, take medications prescribed by the doctor, follow a gentle diet, and adhere to the rules of personal hygiene. If your condition worsens and symptoms appear, you must contact your local physician or call an ambulance.
An initial positive test, even in an asymptomatic case, is a reason for immediate examination of all family members living in the same area as the sick person. It is not their responsibility to comply with the rules of isolation, however, in case of any, even minor, deterioration of the condition, it is necessary to inform the local therapist, who will determine the further course of action.

What to do if you receive a positive COVID-19 test result

A positive test for coronavirus indicates that the patient is sick, is a carrier of SARS-CoV2, or that his immune system has managed to overcome a dangerous infection. The results depend on which laboratory diagnostic method was used for testing - ELISA or PCR. It is important to remember that the reliability of the data obtained varies in the range of 75 - 80%, so if the test results are positive, do not panic. Doctors advise taking a second test, the results of which will help confirm or refute the diagnosis.

The laboratory administration will notify the patient about the results of the laboratory test by sending an email, SMS message or calling the specified number. The order of further actions is determined by the following main factors:

general health of the patient;
technique used to identify the causative agent of COVID-19.

If the diagnosis was carried out using the polymerase chain reaction (PCR), which is currently the gold standard for diagnosing coronavirus infection, a positive result indicates that the patient is currently sick or is an asymptomatic carrier of the pathology. The latter scenario poses a threat to others, especially those who are most vulnerable to infection:

aged people;
children;
men and women with severe chronic pathologies;
cancer patients.

A serological test (ELISA) is prescribed if the PCR is negative. Up to 93% of IgM is detected in PCR-negative patients. The presence of class M immunoglobulins in the blood indicates an acute stage of infection.

What to do if the initial test for coronavirus is positive? The order of further actions will depend on the general condition of the patient. If a positive result is combined with pronounced symptoms of the disease, such as high fever, shortness of breath, dry cough, the patient must be immediately hospitalized in the infectious therapy department. Already on site, repeated testing will be carried out and complex therapy will be prescribed in accordance with WHO protocols.