AMNIOCENTESIS

From Big Medical Encyclopedia

AMNIOCENTESIS (amniocentesis; Greek amnion — a fetal membrane and kentzsis — a puncture) — a puncture of a cavity of amnion for extraction of an amniotic fluid with the diagnostic purpose.

Operation A. it was for the first time offered in 1956 in England by Beavis (D. Page of Bevis), which showed that the analysis of the amniotic waters received in such way at rezuskonfliktny pregnancy has great diagnostic value, napr, is the most effective remedy of a prediction and assessment of severity of a hemolitic disease of a fruit and the newborn. Behind some exceptions And. seldom make in the first half of pregnancy, is more often in 28 weeks, but not earlier than 15 — 16 weeks of pregnancy; repeat Ampere-second a 2 weeks or week interval.

Indications

Existence at the woman of the phenomena of isoimmunization; for diagnosis of some genetically caused diseases, napr, hemophilias. And. it can be used for diagnosis of a perenashivaniye (pregnancy) (see), estimates of the general condition of a fruit, degree of its maturity at various complications of pregnancy (see. Fruit ).

Contraindications: a condition of the menacing abortion, existence of infectious process.

A preparation for surgery

in order to avoid complications at And. it is necessary to define before operation localization of a placenta by radioisotopes, ultrasound (see. Ultrasonic diagnosis ), termografiya (see). Operation is made carefully, in a pure dressing room or the small operating room with observance of all rules of an asepsis and antiseptics.

Course of operation

Fig. 1. The place of amniocentesis depending on localization of a placenta (points designated places of a puncture, black color — a placenta)

And. it can be made transabdominalno and via the channel of a neck of uterus. And. make in position of the pregnant woman lying on spin with the legs bent in knee and hip joints. The place of a puncture is chosen depending on localization of a placenta (fig. 1) and the provision of a fruit, whenever possible away from its head. At it can be located scientific research institute of a placenta on a front body wall of a uterus it is made suprapubic And. after preliminary bladder emptying and assignment of a head of a fruit up. Leather is processed alcohol and iodine, fabrics in the place of a puncture anesthetize 0,5% solution of novocaine. And. make a needle for a lumbar puncture or a usual needle for intravenous injections. Length of a needle no more than 8 — 10 cm to Eagle enter at right angle, slowly and smoothly. The doctor making a puncture feels small resistance during the passing of a needle through an aponeurosis, an amniotic cover and then feeling of a failure at its hit in amniotic waters. At reduction of a uterus during introduction of a needle tactile feelings of the doctor therefore it is necessary to suspend, delay advance of a needle it on 1 — 2 cm are lost and to wait for the end of a fight. After emergence in the syringe of an amniotic fluid carefully suck away necessary quantity it (5 — 10 ml) for a research, delete a needle, grease skin in the place of a puncture with iodine.

Fig. 2. Amniocentesis via the channel of a neck of uterus by means of an amnioskop

After 36 weeks of pregnancy (does not follow earlier since opening of a bag of waters and development of patrimonial activity is possible) And. it can be made via the cervical channel by a puncture of the lower pole of amnion by means of an amnioskop (see. Amnioskopiya ). Amnioskop enter as it is possible more deeply on a back wall of a uterus (fig. 2). A long needle under control of sight make a puncture of amnion whenever possible closer to a uterine wall. Having received necessary quantity of an amniotic fluid, amnioskop delete.

Complications happen seldom. The injury of a placenta is possible — in the syringe blood appears. The needle needs to be removed and more precisely to define localization of a placenta. Damages of a fruit, as a rule, do not happen. There can be an increase in a caption of maternal antibodies at 1 — 2 cultivations as a result of microtransfusions of blood of a fruit in a maternal blood stream. In case of careless carrying out And. via the channel of a neck of uterus there can be an opening of a bag of waters to the subsequent izlitiy amniotic waters and development of patrimonial activity.


Bibliography: Bevis D. Page A. Blood pigments in hemolytic disease of the newborn, J. Obstet. Gynaec. Brit. Emp., v. 63, p. 68, 1956, bibliogr.; Walker W. Role of liquor examination, Brit. med. J., v. 2, p. 220, 1970.

V. M. Sidelnikova.

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