Antenatal diagnosis of hereditary diseases
Obstetrics And Gynecology / / August 12, 2017
disease, as we know, it is easier to prevent than to treat.They are not exception in this sense, and hereditary diseases.Great achievements in their field of prevention linked to the development of prenatal diagnostic techniques, which are also called prenatal, natal and antenatal.Used its methods allow to determine the cases in which we can recommend the restriction of the birth of children in families with inherited defects, termination of pregnancy when detecting abnormalities in the fetus or to begin treatment in utero.
Currently, a number of techniques used in prenatal diagnosis.These methods include X-ray of the skeleton and soft tissues of the fetus, the fetus by ultrasound study, electrocardiography, Fetoscopy and amniocentesis and taking cell research (biopsy) CVS.
X-ray method, or as it is called, fetoamniografiya provide general outlines of the fetus and the state of the gastrointestinal tract by means of simultaneous administration of small amounts of water-soluble and liposoluble cont
New method to detect congenital anomalies in early pregnancy is Fetoscopy.Fetoscopy called direct examination of the fetus by means of a special device - a fiberoptic endoscope inserted into the uterus through the abdominal wall and the uterine wall.With this method it is possible to conduct a direct examination of the fetus, to reveal his malformations, get a blood sample, and even produce intrauterine blood transfusion.Of course, the application of such sophisticated techniques as her mother and the fetus complications can sometimes arise.It is possible, in particular, note the effect of contrast agents and X-ray on the mother and fetus, negative impact on the fetus of intense light (abnormal development of the eye, abortions).
most secure and widely used in the practice of prenatal diagnosis is a method for studying the amniotic fluid and the cells contained therein by amniocentesis and chorionic cells derived from a biopsy.Amniotic fluid consists essentially of fetal urine that he always absorbs and releases again, but contains cellular material and mainly desquamated from the skin, bladder and gastrointestinal tract cells.Sduschivanie cells occurs throughout pregnancy.This is a normal physiological phenomenon.When amniocentesis sterile outpatient setting is a puncture of the anterior abdominal wall of the pregnant woman.A special needle is usually inserted through the mother's abdominal wall, passes two layers of peritoneum, uterine wall and into the amniotic sac, from which care is taken using a syringe with a liquid amniotmcheskaya Listen cells.
Taking chorionic cells is performed by transcervical (through the cervix) biopsy.Horionnaruzhnaya villous shell embryo, from which part of the placenta is formed over time.Through the cervical canal without expanding it into the uterus introduced special biopsy forceps in the direction of CVS.chorionic arrangement direction is determined by ultrasound.Based on the study of chorionic cells can assess the condition of the fetus.Currently instead chorion biopsy aspiration method is widely used.
obtained after amniocentesis or chorionic biopsy cells are introduced into a medium in which they grow and multiply at a temperature of 37 ° C.For an accurate prenatal diagnosis it is important to have a large number of cells by which to assess the condition of the fetus.Therefore, cells artificially create conditions similar to those in which they live in the body.This process is called cell culturing.The cells in such living conditions and divided, and after 9-14 days, you can analyze their condition.
Amniocentesis and chorionic taking virtually safe for mother and fetus, but sometimes when these procedures can be complications, such as miscarriages, damage to child seats and the umbilical cord.They can be avoided by carrying out the procedure under the control of a special ultrasound device.It should be noted that the choice is crucial amniocentesis needle point of administration, which is based on the value of the insertion of the placenta and fetus.puncture point should not match the location of child seats.Placental localization as determined by ultrasound prior to the study.
Amniocentesis is carried out in the II trimester of pregnancy (16-17 weeks.), And the capture of chorionic cells - in earlier periods (7-9 weeks.).Therefore, in recent years researchers have increasingly prefer the latter method, in which prenatal diagnosis is made early.In case of detection of genetic abnormalities in the fetus pregnancy is terminated.These methods are shown for prenatal diagnosis only when the parents are willing to take a decision on the preservation and continuation of pregnancy depending on the results of the study.Before procedures Prenatal studies parents need to explain in detail their diagnostic capabilities, as well as the risk of complications.
Doctors recommend family genetics chorionic biopsy or amniocentesis at risk of having a child with hereditary disorders of 1-5% and higher.The most accepted indications for these studies -the presence of a child with Down syndrome.This syndrome is characterized by the presence of cells in the baby's extra chromosome 21, which leads to a sharp disturbance of mental and physical development of it.It should be noted that the average degree of risk of birth with severe chromosomal abnormalities (including Down syndrome) for any woman about 0.2%.This risk increases significantly with the age of the mother and father.For example, the incidence of Down syndrome increases with maternal age and is according to some reports 15 deaths per 1,000 births to mothers over 40 years old.Recently it found that the probability of having a child with chromosomal abnormalities is increased if both parents are older than 35-40 years.Amniocentesis and chorionic taking produce from the fact that the parents, especially the mother, concerned about the possibility to have a sick child, even at low risk.Parent concerns must be reasonably taken into account in establishing the indications for these studies.For example, the risk of re-birth of a child with Down's syndrome in young mothers (under 35) can be appreciated by many doctors as a small, but a lot of women, and in this case, insist on carrying out prenatal diagnosis.In such a situation, the physician-geneticist takes into account a woman's desire.Sometimes parents want to know the sex of the fetus due to personal reasons and want to terminate the pregnancy, if the fetus is unwanted sex.Research for this purpose is not included in the scope of prenatal diagnosis of hereditary diseases.In this situation, amniocentesis or chorionic biopsy will be done.
fetal ultrasound can be used not only as an auxiliary procedure for amniocentesis and chorionic taking, but also as an independent method of prenatal diagnosis.They are based on the ability of ultrasonic waves reflected from the surface between two media with different densities, which allows them to receive the image on the screen of a cathode ray tube.Usually the first study carried out in periods of 14-19 weeks.pregnancy, when it is possible to accurately determine the size and number of fruits, their compliance with the gestational age, the presence of a head abnormality, spine, limbs, placenta.You can also identify a number of pathological conditions in these terms (developing pregnancy, molar pregnancy, abounding, and so on. d.).The most reliable results when using this method to get the diagnosis of malformations of the central nervous system (anencephaly, hydrocephalus, microcephaly, cerebral herniation, etc..).You can also diagnose certain fetal malformations of the heart, gastrointestinal tract, hydronephrosis, polycystic kidney and agenesis, as well as gross anomalies of the skeleton.
In conclusion, it should be noted that over the past 80 years, the frequency of congenital disorders as the cause of death of newborns increased from approximately 5 to 20%.Basically, such a difference in the figures is related to the improvement of the diagnosis of hereditary diseases at present.The overall incidence of genetic defects in newborns up to 3-5%.Value of prenatal diagnosis of hereditary diseases in the prevention is obvious.
Currently, however, the use of prenatal diagnosis is still limited, its impact on the prevention of hereditary diseases is not too large, but research in this area expanded and deepened, new techniques are used in a growing number of hereditary diseases.In the future, prenatal diagnosis, you can probably be used more widely and its impact on the prevention of hereditary diseases will increase.
12 Aug, 2017