As tests for pregnancy work
The principle of action of similar tests is based on identification in urine of the pregnant woman of a hormone of the horionichesky gonadotrophin of the person (HGP). After fertilization the ovum shares on a germ and fetal covers. One of them (horion) develops a horionichesky gonadotrophin. At further development of pregnancy this hormone is made by a placenta. In tests for pregnancy the special reagents containing antibodies to HGCh are used. In the woman's urine the horionichesky gonadotrophin is developed in the concentration available to detection by a testing method - approximately from the second day following a periods delay after conception. Specialized blood test of HGCh will much quicker reveal – in some days after fertilization, and also will allow to assume pregnancy term.
Types of tests for pregnancy definition
On sale the wide choice of tests is presented, they can be bought freely in any drugstore, and even in a supermarket. At first it is necessary to be defined what of them to get.
There are following types of tests for pregnancy definition:
- So-called a strip tests (in the form of strips) – the cheapest and popular. Represent the strip impregnated with reagent. For testing it is necessary to collect a quantity of morning urine in pure dry ware. After immersion of a test strip to a certain level in a portion of urine and the subsequent expectation within several minutes - it is possible to see result in the form of one or two strips.
- The tablet – in them the paper strip is placed in the plastic case, in it there are two windows, one of them for drawing a quantity of urine - and the second for display of result. As well as for test strips, urine needs to be collected previously in separate capacity. Further by means of a pipette (it is applied in a set) it is necessary to drip some droplets in the window specified on the tablet. In a few minutes in the second window it is possible to check result. Definition accuracy at tablet tests is higher, than at strips, but also they are more expensive.
- The jet – tests of new generation, with high sensitivity. It will be required to place simply the test for some seconds under a flowing stream of urine. In a few minutes it is possible to receive result. Differ in higher price in comparison with the previous.
- Electronic tests for pregnancy – represent a test strip with a digital board, happen the following types:
- the disposable – define pregnancy existence, and also estimated term and sometimes date of estimated childbirth;
- reusable with a set of removable cartridges, are connected to the computer via the USB socket. Allow to trace the HGCh level, term of pregnancy and date of estimated childbirth.
How to carry out the test
The test for pregnancy is effective in some days after . For a strip dough morning urine right after awakening is required. Prepare in advance pure ware for collecting urine.
To receive the most exact results, do not drink liquid and do not urinate within four hours before carrying out dough. Undiluted urine contains the greatest concentration of a hormone. The amount of urine will be required small, about 20-30 ml. It is not recommended to stir up and shake up urine. It is impossible to freeze it. Storage of a portion of urine in the refrigerator at a temperature from 2 to 6 °C is allowed within a day.
Attentiveness and accurate execution of the instruction of the producer guarantee result accuracy to 90 and more percent.
Upon purchase surely check an expiration date as it is not necessary to speak about the accuracy of overdue diagnostic test. It is necessary to store tests for pregnancy in a dry and cool place, after an expiration date - without regrets to throw out.
How to interpret the test
The test strip contains a diagnostic zone (T - Test) and an inspection zone (C - Control). One painted strip when testing (in an inspection zone) confirms the validity of dough, the second points to pregnancy existence.
Results of testing can visually be the following:
- in the presence of two red or pink lines (on early terms the second strip can be poorly expressed) - the test is considered positive;
- only one strip in a control zone is painted, the second is absent - negative result;
- there was no strip – the test does not work (such can be if there was an expiration date, the production technology or storages is violated).
In the presence of doubts the test for pregnancy can be repeated. Some producers let out sets from two-three test strips in one packing. Control testing should be held in 2-3 days.
False positive and lozhnootritsatelny results
There is some probability of an error of testing for pregnancy. Most often such occurs if concentration of a hormone of HGCh in urine of the pregnant woman on early terms is too small, and reagents of dough do not catch it because of low sensitivity. Also other options are possible.
The Lozhnootritsatelny result (if the woman is pregnant, but it denies the test) can be received in the following cases:
- insufficiently qualitative or expired test for pregnancy;
- non-performance of a test condition - insufficiently exact observance of instructions;
- in case of pregnancy interruption threat the HGCh level decreases and is not defined by dough;
- in the presence of the certain diseases (for example, diseases of kidneys) which are followed by violation of release of urine at the same time also removal of products of a metabolite is broken.
False positive estimates of dough (if the woman is not pregnant, and the test shows positive result) are more rare, and are possible in the following cases:
- if stimulation of an ovulation or support of a lyuteinovy phase was carried out, preparations Pregnil, Profazi were used. Thus pregnancy did not come, but any tests for pregnancy or specialized blood test for will show trace reaction within 10-14 days;
- in the presence of tumoral diseases;
- after the performed pregnancy interruption operation (medicamentous or tool interruption) – also within 10-14 days there is a trace reaction of a hormone of HGCh.
If tests show ambiguous results, blood test on HGCh will help to specify pregnancy existence (blood from a vein, is given strictly on an empty stomach).
It should be noted that it is impossible to exclude extra-uterine pregnancy by means of dough, only ultrasonic inspection will help.
InfoAdvisor.net recommends to read the instruction - carefully to study recommendations of the producer concerning testing.
If you did not make the test with morning urine, gynecologists recommend to refrain for four hours from an urination, thus not to accept any liquid to keep sufficient concentration of urine. Further attentively to re-read the instruction and to carry out the test.
In the presence of negative result and the proceeding delay the test is recommended to be repeated in two-three days.
In case of positive result of testing it is necessary to address to the doctor for further inspection of pregnancy.