PLACENTAL PRESENTATION

From Big Medical Encyclopedia

PLACENTAL PRESENTATION (placenta praevia; synonym presentation of an afterbirth) — the morbid condition which is characterized by the wrong implantation of placenta to a wall of a uterus at Krom a part it is in area of an internal uterine pharynx.

Pct it is mentioned in Hippocrates's works. Already in an extreme antiquity it was known that an arrangement placentae (see) in an internal uterine pharynx is the heavy, life-threatening woman pathology. In 16 century data on possible unusual localizations of a placenta in a uterus were published, and in 17 century P. G. Schacher described an arrangement of a placenta in an internal uterine pharynx at the pregnant woman who died of bleeding.

Frequency of cases of Pct averages 0,5%. PLACENTAL PRESENTATION occurs at repeatedly pregnant more often than at pervoberemenny.

Fig. 1 — 3. The main types of placental presentation (1 — an internal uterine pharynx — an isthmus of a uterus, PNA; 2 — a placenta; 3 — an umbilical cord; 4 — fetal membranes). Fig. 1. Full presentation. Fig. 2. Regional presentation. Fig. 3. Side - presentation.

Distinguish two main types of Pct: full (placenta praevia totalis) — when the internal uterine pharynx is completely closed by a placenta, and incomplete, partial (placenta praevia partialis), at Krom the placenta partially blocks an opening of an internal uterine pharynx the edge or occupies its considerable part, and on other extent in a zone of an internal uterine pharynx fetal membranes are defined. Full Pct sometimes call central, the last is rather rare kind of full presentation corresponding to coincidence of the geometrical centers of a placenta and a uterine pharynx. Incomplete Pct often divide into side (placenta praevia lateralis), at Krom a part of a placenta is located in an internal uterine pharynx, and other part is occupied by fetal membranes, and regional (placenta praevia marginalis) — when the most part of an internal uterine pharynx is closed by fetal membranes and the edge of a placenta is defined only on peripheries (tsvetn. fig. 1 — 3). If the edge of the placenta which is located in the field of the lower uterine segment does not reach an internal uterine pharynx, then such arrangement is called a low implantation of placenta. Domestic obstetricians do not carry a low implantation of placenta to Pct. In the USA, England and some other countries it is classified as the kind of PLACENTAL PRESENTATION Seldom found form is a combination of Pct to a partial implantation of placenta to walls of a neck of uterus, a so-called cervical placenta (placenta cervicalis, or placenta isthmicocervi-calis).

B the course of childbirth depending on features of an arrangement and implantation of placenta to a wall of a uterus of relationship between an internal uterine pharynx and a placenta can change. So, e.g., the full placental presentation noted at the beginning of childbirth sometimes gradually passes in side, and side — in regional or on the contrary.

Dystrophic and cicatricial changes of an endometria of a body of the womb as a result of the abortions postponed earlier, patol, childbirth, a puerperal and postabortion infection are the most frequent reason of Pct. According to V. I. Orlov, at 84,8% of pregnant women with Pct in the anamnesis abortions, at 10,9% — the complicated childbirth were noted, 20,2% of patients had inflammatory diseases of internal generative organs.

Changes of an endometria interfere with implantation of an oospore in the place of an attachment of fetal egg where the placenta forms. If implantation was done above an isthmus of a uterus, owing to unfavorable conditions for development of fetal egg the area of a placenta kompensatorno increases at the expense of what food of a fruit improves, pregnancy remains. In the course of formation the placenta can extend for area of the lower segment of a uterus and internal uterine pharynx. It is a so-called secondary isthmic placenta (placenta Capsularis) developing in the place of contact with capsular decidua (see) from not atrophied vorsin where smooth chorion — chorion laeve (would have to be formed see. Fetal membranes ). Rather often at presentation in a placenta additional segments develop. At pervoberemenny sometimes find thinning of a decidua in cases of Pct as manifestation infantility (see). There is an assumption that the Pct results from later, than normal, emergence of implantation abilities (the corresponding enzymatic properties of a trophoblast) in the fetal egg which is moving ahead in a cavity of the uterus.

Pathoanatomical data

indicate Pathoanatomical data an important role in development of Pct of inflammatory changes of a decidua and growth of connecting fabric. Along with dystrophic processes in a uterus and a pladenta also shifts of compensatory character are found. Result of separation of a placenta from a wall of a uterus with a rupture of intervillous spaces, in to-rykh the maternal blood washing vorsina of chorion circulates, bleeding is. Placental detachment comes from a wall of a uterus sometimes during pregnancy owing to stretching of the lower uterine segment which is gradually a part of a fruit bed. Development of placental detachment is also promoted by reductions of a uterus, especially in labor when each fight is followed by the increase in intrauterine pressure leading to protrusion of a placenta and fetal membranes in a gleam of an internal uterine pharynx. Walls of the lower uterine segment and a neck of uterus are displaced up at the expense of retraction of uterine muscles at this time, breaking an implantation of placenta to a wall of a uterus even more. Clinically the Pct is shown by hl. obr. uterine bleedings (see) which usually begin without the visible reasons or in connection with an exercise stress, a nerve strain. S. I. Pavlova noted that a considerable part of women indicates the sexual intercourse preceding bleeding. Most often bleeding begins in the third trimester of pregnancy. The place of an implantation of placenta is lower, the bleeding develops earlier. At most of women with incomplete Pct bleeding begins in labor, with full — at pregnancy. Bleeding can periodically stop at reduction of intensity of uterine reductions and thanks to rather expressed processes of a thrombogenesis in the place of placental detachment. The stop of bleeding in labor at partial Pct is promoted izlity amniotic waters and by intensive reduction of a uterus: the placenta at a fight falls, and the prelying part of a fruit presses the separated part of a placenta to the place of amotio and has thus the tamponing effect. In cases of full Pct bleeding usually progresses owing to what development is possible anemias (see), and at massive blood losses — hemorrhagic shock (see).

The most dangerous complications are connected with repeated bleeding, a cut can aggravate already developed anemia and shock. Ruptures of a neck of uterus happen a source of such bleeding, edges the vaskulyarizirovana owing to proximity of a placenta is loosened and considerably. In afterbirth and early puerperal the periods of bleeding often arise also in connection with insufficient sokratitelny ability of a uterus in the area placental platform (see), disturbance of placental detachment from a wall of a uterus as a result patol, changes and with the smaller thickness of a decidua in the lower segments of a uterus, up to development of a true increment of a placenta (see. Hypotonic bleedings , Childbirth ). Items promotes development of an embolism by amniotic waters, edges is followed by bleeding as a result of decrease in coagulative properties of blood, acute fibrinolysis (see). Seldom there are cases air embolisms (see), the women who are coming to an end with sudden death. Development of septic complications in a puerperal period is promoted by proximity of the placental platform to a vagina, the strengthened processes of a thrombogenesis in this area, frequent vaginal examonations and operative measures, the phenomena of anemia at women in childbirth. Amotio of a part of a placenta from a wall of a uterus, a loss of blood at a fruit lead to its hypoxia (see. Asphyxia of a fruit and newborn ). The high arrangement of the prelying head of a fruit over an entrance to a basin is characteristic of Pct, in many cases pelvic presentation or the wrong provision of a fruit is observed. According to E. V. Sokolov, head presentation meets in 66,17% of cases of Pct, pelvic — in 8,15%, the cross provision of a fruit — in 13,82%, slanting — in 11,86%.

The diagnosis

the Diagnosis is made on the basis of emergence of uterine bleeding in the second half of pregnancy or in labor. In the absence of plentiful bleeding additional researches are preferable to specification of the diagnosis not vulval, but. From them the safest and reliable is ultrasonic scanning of a placenta (see. Ultrasonic diagnosis, in obstetrics and gynecology ). Use of thermovision is possible (see. Termografiya ), however with its help obtain insufficiently accurate data at an arrangement of a placenta on a back wall of a uterus. Use of radiological methods is less desirable, in particular X-ray analysis (see) since they are connected with impact on a fruit of ionizing radiation. The X-ray analysis is carried out as without contrasting using special aluminum filters, and with contrasting of a bladder contrast liquid or air. Existence of a wide layer of fabric between a wall of a bubble and the prelying head of a fruit testifies to Pct. Apply also an amniografiya); after introduction to an amniotic cavity by amniocentesis of contrast agents make x-ray films (see. Pregnancy ). To rentgenol, to methods various options of introduction to a blood stream of contrast agents which collect in vessels of a placenta — intravenous belong platsentografiya (see), aortografiya (see), but these methods are unsafe and therefore they are used seldom. Amnioskopiya (see) for diagnosis of Pct it is inexpedient as it is accompanied by possible strengthening of bleeding. After the termination of bleeding perform inspection of a vagina and neck of uterus by means of mirrors (see. Gynecologic research ), allowing to exclude patol, the changes (polyps, erosion, cancer, etc.) which are the possible reasons of bleeding. At careful vaginal examonation by a palpation of the arches in the location of a placenta it is possible to reveal a pulsation of vessels, and between a wall of the arch and the prelying head — to propalyshrovat a placenta. Vaginal examonation with introduction of a finger to the cervical channel and identification of species of Pct is carried out in labor and at rather expressed bleeding when it is necessary to resolve an issue of obstetric tactics. Such research in view of danger of strengthening of bleeding is conducted in the operating room in conditions, at to-rykh the patient help can be immediately given, up to Cesarean section (see).

The pct should be differentiated, as a rule, with premature amotio of normally located placenta (see. Premature placental detachment ), for a cut unlike Pct bleeding against the background of pain, morbidity, tension of a uterus, the disturbances much stronger expressed in a condition of a fruit is characteristic up to his death, lack of a placenta in a uterine pharynx at vaginal examonation. The roughness of fetal membranes testifies to a low implantation of placenta during vaginal examonation. After the end of childbirth about degree of proximity of a placenta to an internal uterine pharynx it is possible to judge by distance from an opening in covers of an afterbirth (it corresponds to a projection of an internal uterine pharynx at full opening of a neck) to the closest edge of a placenta.

Treatment

Treatment of Pct is carried out in a hospital. At massive bleeding regardless of a type of Pct and a condition of a fruit Cesarean section is shown. This operation is made at full Pct and at moderate bleeding, and also at a combination of Pct to the wrong provision of a fruit. Apply the intubation combined anesthesia to anesthesia. The uterus is cut in the lower segment cross section, resort to a korporalny section when the woman or a fruit are in the menacing state. And after Cesarean section carry out hemotransfusion, infusional therapy to time. At a cervical implantation of placenta Cesarean section is completed hysterectomy (see).

At the small, from time to time stopping bleeding appoint the high bed rest, drugs reducing intensity of uterine reductions (a candle with a papaverine, magnesium sulfate, progesterone, hypnotic drugs), increasing coagulability of blood (Vikasolum), strengthening a vascular wall (Ascorutinum), promoting regeneration of blood (B12 vitamin, antianemin), carry out prevention of a hypoxia of a fruit, hemotransfusion. V. M. Sadauskas at premature pregnancy recommends obshivany necks of uterus in an internal uterine pharynx a circular seam that promotes a stop of bleeding and prevention premature births (see). If bleeding stops, then 2 — 3 days later make a research by means of mirrors, and then vaginal examonation (in the operating room ready for performance of a laparotomy). When bleeding does not stop or renews, despite the carried-out therapy, in the operating room at vaginal examonation establish a type of Pct. At full presentation resort to Cesarean section, at partial — instrumentalno, it is desirable by means of mirrors, open a bag of waters (see. Childbirth ). If bleeding does not stop, uterine reductions are insufficient, the head of a fruit does not fall and does not tampon the exfoliated part of a placenta, impose craniodermal nippers according to Wilt or according to Ivanov (see. Craniodermal nippers ), to the Crimea suspend the load having weight no more than 400 g. Bringing down of a leg with suspension of the same load in cases of buttock presentation is applied at a dead or impractical fruit. Right after the birth of the child in natural patrimonial ways make manual department and removal of an afterbirth (see. Afterbirth period), for a stop of bleeding enter methylergometrine, oxytocin. At atonic bleedings, deep growing vorsin the prelying placenta in a wall of a uterus the hysterectomy is shown. In order to avoid accession of an infection appoint antibiotics, continue hemotransfusions, control and korrigirut a condition of coagulant system of blood. Newborn Pct in cases require special attention of neonatolog, and in the subsequent — pediatricians.

The forecast

the Forecast for the woman is rather serious. During the rendering the timely help danger considerably decreases and most of patients completely recovers with preservation of working capacity and functional full value of reproductive system. The lethality at Pct gradually decreases. This indicator, according to F. P. Patuishnskaya's (1933 — 1938) observations, was equal to 13%, A. D. Alovsky (1936 — 1945) — 3,56%, V. I. Orlova (1960 — 1972) — 1,5%. For a fruit and the newborn the forecast is doubtful because of high percent of premature births, a pre-natal hypoxia and a birth trauma. Perinatal mortality (see) at Pct remains rather high, but has a nek-ry tendency to decrease. By data K. Ya. Skuya (1949 — 1955), it made 30,1% given E. V. Sokolova (1953 — 1969) — 18,9%.

Prevention

Prevention is directed to fight against abortions, the prevention and timely treatment of puerperal, postabortion, gynecologic inflammatory diseases, to early detection and treatment of infantility.



Bibliography: Anisimova M. I., Sokolov E. V. and A. M Foy. Experience of conducting pregnancy and childbirth at presentation of an afterbirth, Vopr. okhr. mat. also it is put., t. 16, No. 9, page 43, 1971; Oh to-sh e e b’ H. C. Uterine bleedings in obstetrics, page 142, Kiev, 1970; Becker S. M. Pathology of pregnancy, page 94, L., 1975; The Multivolume guide to obstetrics and gynecology, under the editorship of L. S. Persianinov, t. 3, book 2, page 233, M., 1964; V. I Eagles. Some questions of a course of pregnancy at placental presentation, in book: Vopr, akush., ginek, and gigabyte. female labor, under the editorship of P. Ya. Lelchuk, century 7, page 32, Rostov N / D., 1974 Persianinov L. S. Obstetric seminar, t. 1, page 219, Tashkent, 1973; Savelyeva G. M. Conducting pregnancy and childbirth at premature amotio and placental presentation, Owls. medical, No. 6, page 106, 1977; Hibbard L. T. Placenta praevia, in book: Benson B. C. and. lake of Current obstet, and. gynec, diagnosis a. treatment, p. 668, Los Altos, 1978.


V. I. Grishchenko.

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