From Big Medical Encyclopedia

AMNIOTIC WATERS (liquor amnii; synonym: fetal waters, amniotic fluid) — the liquid which is in amnion (an amniotic bag). Lakes of century are an intermediate zone between an organism of mother and a fruit during all pregnancy and the necessary environment for a fruit performing diverse functions on ensuring its growth and development.

Lakes of century are formed at the highest vertebrate animals (mammals, W. h the person), etc., to-rykh call amniota unlike group of the vertebrates (fishes, etc.) who do not have amnion and amniotic waters (anamnia).

Mechanisms of education

Was considered that O. are formed century by hl. obr. from urine of a fruit. However Alfeld (J. F. Ahlfeld) in 1879 in amnion of a fruit with total absence of outside uric bodies and fusion of an anal orifice found 500 ml of amniotic liquid, i.e. as well as in normally developed fruits. On this basis Alfeld drew a conclusion that without wetting a fruit is O.'s source of century. The opinion on secretory activity of an epithelium of amnion as a source of education of O. of century was for the first time stated by K. N. Vinogradov in 1871

A. V. Vikulov (1954) considers that O. are formed century of various sources in different durations of gestation: in the embriotrofichesky period they are transudate of a trophoblast, in the period of vitelline food — transudate a sintition of fibers of chorion (from blood of mother), later — a secret of an epithelium of amnion.

Composition of amniotic waters

Properties O. of century change depending on duration of gestation, a condition of mother and a fruit. Volume them in 8 weeks of pregnancy makes 5 — 10 ml, in 10 weeks — apprx. 30 ml, in 18 — 20 weeks — on average 250 — 280 ml. The maximum volume of O. of century (1000 — 1500 ml) is noted during the period between 30 — the 38th for weeks of pregnancy, by the end of pregnancy it makes apprx. 600 ml; their smaller quantity is called oligoamnios (see), and bigger — hydramnion (see).

At the beginning of O.'s pregnancy century colourless and transparent, by the end of pregnancy become rather turbid because of hit in them the fruit separated sebaceous glands of skin, vellus hairs (lanugo), scales of epidermis, sometimes leukocytes. Specific weight of O. of century at the full-term pregnancy fluctuates within 1002 — 1028, reaction alkalescent or close to neutral (pH 8,15 — 6,98). O.'s viscosity of century rather small (1, 10 — 1,26 conventional units); surface intention of 46,3 — 50,6 dynes/cm, t ° froze 0,475 — 0,495 °. The radioactive materials having P-radiation are found in O. for century. According to A.S. Volkova (1967), the content of mineral substances is equal to century in O. to 0,71%. By the end of pregnancy of O. of century contain: 175,3 mg / 100 ml of sodium, 363 mg / iOO of ml of chlorine, 27 mg / 100 ml of potassium, 2,46 mg / 100 ml of phosphorus, 7,35 mg / 100 ml of calcium; mineral composition of O. of century is rather stable. The most important component of O. of century are proteins (210 — 390 mg / 100 ml). Donat and Noyendorf (H. Donat, To. Neuendorf, 1972) in O. century found 12 protein fractions. O. contain century also free amino acids, fats and lipids in the form of fat to - t, vitamin A, vitamins of group B, ascorbic to - that, a chorionic gonadotrophin, steroid hormones, bilirubin, enzymes (erericini, alkaline a phosphobasin, hyaluronidase). Insulin is present at O. century from 16th week of pregnancy only at a live fruit. Lakes of century contain also thromboplastin, fibrinolysin, X and XIII factors of blood serum. Lakes of century have specific features.

Physiological value

the Metabolism between an organism of mother, O. and a fruit occurs century during all pregnancy. Value O. of century in a metabolism of a fruit follows from their chemical structure, to-ry in turn depends on a metabolism between O. century and maternal blood (through a chorial plate and amnion). From a cavity of amnion get to an organism of a fruit of O. of century through skin, a digestive tract and lungs. By 25th week of embryonic development skin of a fruit becomes keratinized, the metabolism through skin decreases; at the end of pregnancy skin and bronchial tubes of a fruit play the lesser role in O.'s transport of century, major importance gets swallowing by O.'s fruit of century, to-rye come to his digestive tract. The fruit swallows from 300 to 500 ml of liquid, and in it emits urine and an alveolar secret from respiratory tracts. Permeability for O. century of a fetalis surface of a placenta and an umbilical cord remains, through to-rye liquid passes from a cavity of amnion into blood of a fruit and in the opposite direction.

Intermediate zones (O. century and a spongy layer of fetal membranes) «will amortize» pathogenic influences on a fruit nek-ry fiziol, and patol, changes of a condition of a maternal organism, promote maintenance of a homeostasis of a fruit. Important buffer function is performed also by the amniokhorialny space filled with amniokhorialny liquid, structure the cut differs from O.'s structure of century and edge not only «will amortize» mechanical impact on a fruit, but also carries out mediation between a mucous membrane of a uterus and O. of century.

In O. century there is a constant and bystry metabolism: each hour is replaced 1/3 part of water, 13 mekv sodium and 0,6 mekv potassium. Lakes of century are completely updated during 2 hours 54 min. High speed of education and return absorption of O. of century, gradual change of their quantity and quality (depending on duration of gestation, a condition of a fruit and mother) demonstrate that O. century play an important role in a metabolism between mother and a fruit.

Lakes of century are important for fetation, a cut variously during the separate periods of pregnancy. In the first weeks of development the germ has a consistence, the little O., different from a consistence, century that does possible independent development of such germ not only as whole, but also as complex of the separate unevenly developing parts. Lakes of century together with a front abdominal wall and a wall of a uterus are also the most important part of the protective system protecting a fruit from damages, first of all mechanical. The new form of activity of a fruit — the movements amplifying in process of its development and possible only in fluid medium develops in the next weeks of pre-natal development. With development of a physical activity thanks to a nappe between it and a wall of a uterus the fruit can adopt the provision from the point of view of physiology of childbirth the most favorable. Besides, O. century protect a fruit from direct contact with a wall of fetal egg, providing continuous sliding of surfaces of skin of a fruit and amnion. In cases of insufficient number of O. of century or their absence are possible an union of skin of a fruit with amnion and various malformations (see. Amniotic threads, banners, unions ).

Influence on a childbed

century are usually divided by O. into two unequal parts. The waters which are in a bag of waters are lower than a belt of contact of a head of a fruit with a basin of the woman, are called front waters. Back waters wash a trunk and the basis of a head of a fruit. In the absence of a belt of contact in cases of a mobile head over an entrance to a basin or at the cross and slanting provision of a fruit division of waters into front and back does not happen.

The lake of century disclosure is promoted, by necks and activities of muscles of a uterus.

Cases when comes take place premature bursting of waters (see) in early durations of gestation that usually conducts to premature abortion or early delivery. It is necessary to remember what is sometimes observed izlity amniokhorialny (so-called false) waters when the chorial plate is broken off, and amnion remains whole; the fruit at the same time does not suffer and pregnancy develops up to the end. Diagnosis premature O.'s izlitiya of century, existence of a hydramnion or oligoamnios is very important for definition of tactics of the obstetrician in labor (see. Childbirth ).

Methods of diagnostic testing

the Research O. of century allows to estimate a condition and a maturity of a fruit and in necessary cases timely to resolve an issue of delivery or performing the corresponding corrective therapy. Century from a cavity of amnion apply a puncture to O.'s extraction (see. Amniocentesis ) with the subsequent studying of its cellular structure (tsitol, a method), a sex chromatin, a blood group and a Rhesus factor. Conduct also histochemical, cytogenetic, biochemical researches O. of century allowing to determine content in them protein fractions, enzymes, steroid hormones, bilirubin and also carbohydrate, amino-acid lipidic and electrolytic structure and acid-base equilibrium; use spectrophotometric methods, an electrophoresis, a chromatography, fluorescent polarization of O. of century

Rupnarayan Singh (S. Roopnarinesingh, 1974) with soavt, believe that the simultaneous research of enzymes and chemical components O. of century allows to define more precisely duration of gestation and to judge degree of a maturity of a fruit. For definition of degree of a maturity of a fruit and a possibility of its defeat at a Rhesus factor conflict, for prevention of prematurity and a perenashivaniye, and also for the solution of a question of terms of a rodovozbuzh-deniye at pregnant women with toxicoses, a diabetes mellitus, defeat of a placenta great practical value has a research of lipids of O. of century. So, the size of the relation le-tsitin / sphingomyelin, smaller 1,5, indicates immaturity of lungs, and 1,8 and more — a maturity of lungs. In assessment of a maturity of a fruit the research of contents in O. century of creatinine is of great importance. Concentration of creatinine of St. 1,6 mg / 100 ml testifies to a sufficient maturity of a fruit. Degree of a maturity of a fruit century milk to - you estimate also by determination of content at O., dehydrogenases, alkaline and acid phosphatases, estriol.

Studying of acid-base equilibrium of O. of century gives the chance to judge a condition of a fruit at a perenashivaniye, late toxicoses, a Rhesus factor - conflict pregnancy, a diabetes mellitus when expressed is stated acidosis (see). The chromosomal analysis of culture of cells of O. of century allows to establish extent of defeat of a fruit as a result of influence of these or those mutagen factors. Besides, it is used for sex determination of a fruit (see. Floor ).

For diagnosis of the inborn diseases of a fruit connected with disturbance of carbohydrate metabolism century glikozidaz conduct a research on contents in O.

Bibliography: Antenatal diagnosis of genetic diseases, under the editorship of A. E. X. Emery, the lane with English, page 105, M., 1977; P and l-l and d both G. A. and Brand. A. Diagnostic value of a research of amniotic waters, Akush, and ginek., No. 4, page 58, 1978; Persianinov JI. Page, S and-delnikova B.M. and Shpakova R. 3. The acid-base condition of amniotic waters is normal also at a Rhesus factor immunization, in the same place, No. C, page 20, 1973; Rozovsky I. S. and B and x are of e in V. A. Fe-toamniografiya and a fetoskopiya as methods of prenatal diagnosis, in the same place, No. 4, page 1, 1978; Savelyeva G. M. Biochemistry of an amniotic fluid and its relation to a condition of a fruit and newborn, in the same place, No. 3, page 1, 1974; With and of e-t e of about O. A. and. lake of Identification of and pressor polypeptide in human amniotic fluid, Amer. J. Obstet. Gynec., v. Ill; p. 1075, 1971; Donat H. u. Neuendorf K. Proteinspektrum des Fru-chtwassers, Zbl. Gynak., Bd 94, S. 408, 1972; Roopnarinesingh S. Morris D. Amniotic fluid urea and creatinine in normal pregnancy and in pre-eclampsia, J. Obstet. Gynaec. Brit. Cwlth., y. 78, p. 29, 1971.

G. A. Palladi.