Placenta previa – definition.
Placenta presentation (placenta praevia – lat.) Is a term used in obstetrics, with which various options for the location of the organ in the cervical region are indicated. This means that the placenta is located in the lower part of the uterus and overlaps the birth canal. It is the location on the path of the fetus that is born that reflects the Latin notation of the presentation – placenta praevia, where the word “praevia” consists of two: the first preposition “prae” and the second root “via”. “Prae” means “before”, and “via” means the path. Thus, the literal translation of the term placenta praevia means literally “located on the path of the placenta.
Placenta previa currently refers to the pathology of pregnancy, and at terms of 37 to 40 weeks gestation occurs in 0.2 – 3.0% of cases. At earlier stages of pregnancy, placenta previa is more frequent (up to 5-10% of cases), however, as the fetus grows and develops, the uterus stretches, and its child’s place moves further away from the cervical region. Such a process, obstetricians are called “migration of the placenta.
To understand the essence of the pathological location of the placenta, called presentation, it is necessary to imagine the structure of the uterus, which is conventionally divided into body, bottom and neck. The cervix is located in the lower part of the organ, and its outer part is lowered into the vagina. The upper part of the uterus, which is a horizontal pad directly opposite the neck, is called the bottom. And the side walls, located between the bottom and neck, are called the body of the uterus.
Cervix is a kind of tightly compressed cylinder of muscle tissue with an opening inside, called the cervical canal. If this cylinder is stretched in width, the cervical canal widens significantly, forming a hole 9 – 11 cm in diameter, through which the child can leave the uterus during the labor process. Beyond the birth the cervix is tightly clamped, and the opening in it is very narrow. To visualize the physiological role of the cervix, mentally draw a bag, strapped with a string. It is the part tied with a rope that is the tightly compressed neck of the uterus, which keeps the contents of the bag from falling out. Now turn this bag with a hole downward, so that the piece, strapped by a string, turned to the floor. In this form, the bag completely repeats the location of the parts of the uterus and reflects the role of the neck. Uterus in the woman’s belly is located just like this: the bottom is in the upper part, and the cervix is at the bottom.
In childbirth, the cervix of the uterus opens (claps) under the action of fights, resulting in a hole through which the child can pass. With regard to the image of the bag, the process of opening the cervix is equivalent to simply untying the string, which tightens its opening. As a result of this “discovery” of the bag, everything that is in it will fall out. But if you untie the opening of the bag and simultaneously place an obstacle in front of it, the contents will remain inside, because they simply can not fall out. Likewise, a child can not be born if there is any obstacle in his path, in the place of the opening of the cervix. It is such an obstacle and is the placenta, located in the cervix. And such an arrangement that interferes with the normal course of the birth act is called placenta previa.
With the presentation of the placenta, high mortality of newborns is recorded. which is from 7 to 25% of cases, depending on the technical equipment of the maternity hospital. High infant mortality with placenta previa is due to the relatively high incidence of premature birth, fetoplacental insufficiency and abnormal fetal position in the uterus. In addition to high infant mortality, placenta previa can cause a terrible complication – bleeding in a woman, from which about 3% of pregnant women die. It is because of the danger of child and maternal mortality that placenta previa is referred to the pathology of pregnancy.
Types of placenta previa and their characteristics.
Depending on the specific features of the location of the placenta in the cervical region, several types of presentation are distinguished. Currently, there are two main classifications of placenta praevia. The first is based on determining its location during pregnancy using transvaginal ultrasound (ultrasound). The second classification is based on determining the position of the placenta in the process of delivery when the cervix is opened 4 or more cm. It should be remembered that the degree and type of presentation can vary with the growth of the uterus or with the expansion of the cervix.
Based on the data of transvaginal ultrasound, produced during pregnancy, the following varieties of placenta diligence are distinguished: 1. Complete presentation; 2. Incomplete presentation; 3. Low presentation (low location.
Full placenta previa.
Full placenta previa (placenta praevia totalis – lat.). In this case, the placenta completely covers the inner opening of the cervix (internal pharynx). This means that even if the cervix is fully opened, the child will not be able to enter the birth canal, as the placenta blocking the way out of the uterus will block it. Strictly speaking, births in a natural way with complete placenta previa are impossible. The only option for delivery in this situation is a cesarean section. This location of the placenta is noted in 20 – 30% of the total number of cases of presentation, and is the most dangerous and unfavorable in terms of the risk of complications, child and maternal mortality.
Incomplete (partial) placenta previa.
With incomplete (partial) presentation (placenta praevia partialis), the placenta covers the inner opening of the cervix only partially, leaving a small portion of its total diameter free. Partial placenta previa can be compared to a plug that covers part of the diameter of the tube, not allowing water to move at the fastest possible speed. Also, incomplete presentation is the occurrence of the lower part of the placenta at the very edge of the opening of the cervix. That is, the lowest edge of the placenta and the wall of the inner opening of the cervix are at the same level.
With incomplete presentation of the placenta in the narrow part of the lumen of the cervix, the baby’s head, as a rule, can not pass, so birth in the natural way in the overwhelming majority of cases is impossible. Frequency of occurrence of this type of presentation ranges from 35 to 55% of cases.
Low (lower) placenta previa.
In this situation, the placenta is located at a distance of 7 or less centimeters from the perimeter of the entrance to the cervical canal, but does not reach it. That is, the area of the internal throat of the cervix (entrance to the cervical canal) with low presentation is not captured and does not overlap with the placenta part. Against the background of low placenta previa, natural delivery is possible. This variant of pathology is the most favorable from the point of view of the danger of development of complications and gestation.
According to the results of ultrasound, more often in recent years for clinical practice obstetricians have resorted to determining not the species, and the degree of placenta previa during pregnancy, which are based on the amount of overlap of the inner opening of the cervix. Today on ultrasound, the following four degrees of placenta previa are distinguished.
I degree – the placenta is in the region of the cervical opening, but its edge is not less than 3 cm apart from the throat (conditionally corresponds to a low presentation of the placenta.
II degree – the lower part of the placenta is located literally on the edge of the entrance to the cervical canal, but does not overlap it (conditionally corresponds to incomplete placenta previa.
III degree – the lower part of the placenta blocks the entrance to the cervical canal completely. In this case, most of the placenta is located on any one wall (anterior or posterior) of the uterus, and only a small area closes the entrance to the cervical canal (conditionally corresponds to the full placenta previa.
IV degree – the placenta is completely located on the lower segment of the uterus and blocks the entrance to the cervical canal by its central part. At the same time on the anterior and posterior walls of the uterus are the same parts of the placenta (conditionally corresponds to the full placenta previa.
The listed classifications reflect the placenta previa during pregnancy, determined by ultrasound.
In addition, for a long time, the so-called clinical classification of placenta previa was used, based on determining its location in the process of the birth act when the cervix was opened 4 cm or more. Based on vaginal examination during labor, the following types of presentation of the placenta are distinguished.
Central placenta previa (placenta praevia centralis.
Lateral presentation of the placenta (placenta praevia lateralis.
Regional placenta previa (placenta praevia marginalis.
Central placenta previa.
In this case, the entrance to the cervical canal on the side of the uterus is completely blocked by the placenta, when the surface is felt with a finger inserted into the vagina, the doctor can not determine the membranes. Natural births with central placenta previa are impossible, and the only way for a child to appear in this situation is by a cesarean section. Relatively speaking, the central placenta previa, determined during the vaginal examination in childbirth, corresponds to the full, and also III or IV degree by ultrasound results.
Lateral presentation of the placenta.
In this case, during a vaginal examination, the doctor determines the part of the placenta that closes the entrance to the cervical canal, and the rough surrounding membranes next to it. A lateral presentation of the placenta, determined by a vaginal examination, corresponds to an incomplete (partial) or II-III degree ultrasound.
Regional placenta previa.
During the vaginal examination the doctor determines only the rough fetal membranes protruding into the lumen of the cervical canal, and the placenta is located at the very edge of the internal pharynx. The marginal presentation of the placenta, determined by vaginal examination, is consistent with the results of ultrasound examination of incomplete (partial) or I-II degrees.
Posterior placenta previa (placenta previa on posterior wall.
This condition is a special case of incomplete or low presentation, in which the main part of the placenta is attached to the back of the uterus.
Front placenta previa (placenta previa on the anterior wall.
This condition is also a particular case of incomplete or low presentation, in which the main part of the placenta is attached to the front wall of the uterus. Attaching the placenta to the anterior wall of the uterus is not a pathology, but reflects a variant of the norm.
In most cases, the anterior and posterior placenta previa is determined by the results of ultrasound until the 26th-27th week of pregnancy, which during 6-10 weeks can migrate and at the time of delivery come to a normal position.
Placenta previa – causes.
The placenta is formed on that part of the uterus, where the fetal egg is attached. Therefore, if the egg is attached to the lower wall of the uterus, the placenta will form in this part of the organ. The place for attachment is “selected” by a fetal egg, and it looks for a portion of the uterus that has the most favorable conditions for its survival (good thick endometrium, absence of neoplasms and scars, etc.). If the best endometrium for any reason was in the lower segment of the uterus, the fetal egg will attach to that place, and subsequently this will lead to placenta previa.
The reasons for the attachment of the fetal egg in the lower segment of the uterus and the subsequent formation of placenta previa are due to various factors that, depending on the original nature, can be divided into two large groups: 1. Uterine factors (depending on the woman); 2. Fetal factors (depending on the characteristics of the fetal egg.
Uterine factors are various pathological changes in the uterine mucosa (endometrium) formed during inflammatory diseases (endometritis, etc.) or intrauterine manipulation (abortion, diagnostic curettage, caesarean section, etc.). Fetal factors are a decrease in the activity of enzymes in the membranes of the fetal egg, which allow it to be implanted into the mucous membrane of the uterus. Due to a lack of enzyme activity, the egg “slips” past the bottom and walls of the uterus and is implanted only in its lower part.
Currently, for placental presentations, the following conditions refer to maternal causes.
Any surgical interventions on the uterus in the past (abortion, cesarean section, removal of fibroids, etc.
Childbirth with complications.
Myoma of the uterus.
Anomalies in the structure of the uterus.
Underdevelopment of the uterus.
Multiple pregnancy (twins, triplets, etc.).
In view of the fact that most of the causes of placenta previa occur in women who have had any gynecological diseases, surgical interventions or childbirth, this complication in two-thirds of cases is noted in repeatedly pregnant women. That is, women, pregnant for the first time, account for only 1/3 of all cases of placenta previa.
To the plausible reasons for the presentation of the placenta include the following factors.
Inflammatory diseases of the genital organs (adnexitis salpingitis, hydrosalpinx, etc.).
Disorders of the hormonal balance.
Given the listed possible causes of placenta previa, the following women are considered to be at risk for developing this pathology.
Weighed obstetrical anamnesis (abortions, diagnostic curettage, complicated births in the past.
Postponed in the past, any surgical interventions on the uterus.
Neuro-endocrine disorders of regulation of menstrual function.
Underdevelopment of the genitals.
Inflammatory diseases of the genital organs.
Myoma of the uterus.
Pathology of the cervix.
Diagnosis of placenta previa.
Diagnosis of placenta previa can be based on the characteristic clinical manifestations or on the results of objective studies (ultrasound and bimanual vaginal examination). The signs of placenta previa are as follows.
Bloody discharge from genital tracts of bright scarlet color with completely painless and relaxed uterus.
High standing of the bottom of the uterus (the indicator is greater than that characteristic for this period of pregnancy.
Incorrect position of the fetus in the uterus (pelvic presentation of the fetus or transverse location.
Noise of blood flow through the vessels of the placenta, clearly distinguished by the doctor during auscultation (listening) of the lower segment of the uterus.
If a woman has any of the listed symptoms, the doctor suspects placenta previa. In such a situation, a vaginal examination is not performed, as it can provoke bleeding and premature birth. To confirm the preliminary diagnosis of “placenta previa,” the gynecologist sends the pregnant woman to the ultrasound. Transvaginal ultrasound can accurately determine whether a given woman has placenta previa, and also assess the degree of overlap in the uterine throat, which is important for determining the tactics of further management of pregnancy and the choice of the method of delivery. Currently, ultrasound is the main method of diagnosing placenta previa, because of its high information and safety.
If ultrasound can not be done, then to confirm the diagnosis of “presentation of the placenta” the doctor produces a very careful, accurate and careful vaginal examination. With the placenta previa, the gynecologist senses the spongy tissue of the placenta and the rough membranes with fingertips.
If a woman does not have any clinical manifestations of placenta previa, that is, the pathology proceeds asymptomatically, then it is detected in screening ultrasound studies, which are compulsory at 12, 20 and 30 weeks of pregnancy.
Based on the ultrasound data, the doctor decides whether a given woman can later perform a vaginal examination. If the placenta previa is complete, then a standard gynecological two-hand examination can not be carried out, under any circumstances. With other types of presentation, you can only very carefully examine a woman through the vagina.
Ultrasound diagnosis of placenta previa is currently the most informative and safe method for detecting this pathology. The ultrasound can also refine the presentation (full or partial), measure the area and thickness of the placenta, determine its structure and identify areas of detachment, if any. To determine the various characteristics of the placenta, including the presentation, ultrasound should be done with a moderate filling of the bladder.
If placental presentation is revealed, ultrasonography is performed periodically, at intervals of 1 to 3 weeks, in order to determine the rate of its migration (movement along the walls of the uterus is higher). To determine the position of the placenta and assess the possibility of conducting natural births it is recommended to perform ultrasound on the following terms of pregnancy – at 16, 24 – 25 and 34 – 36 weeks. However, if there is a possibility and desire, ultrasound can be done weekly.
Placenta previa – symptoms.
The main symptom of placenta previa is a recurrent, painless bleeding from the genital tract.
Bleeding after placenta praevia.
Bleeding during placenta previa can develop at different gestation times – from 12 weeks until the very birth, but most often they are noted in the second half of pregnancy due to a strong stretching of the walls of the uterus. At presentation of the placenta bleeding to 30 weeks are observed in 30% of pregnant women, in the periods of 32-35 weeks also in 30%, and in the remaining 30% of women they appear after 35 weeks or at the beginning of labor. In general, with the placenta previa, bleeding during pregnancy is observed in 34% of women, and in the period of childbirth – in 66%. During the last 3 to 4 weeks of pregnancy, when the uterus is particularly severely contracted, bleeding may increase.
Bleeding in the presentation of the placenta is due to its partial detachment, which occurs as the uterus wall expands. When detaching a small section of the placenta, its vessels are exposed, from which bright red blood flows.
To provoke bleeding with placenta previa can various factors, such as excessive physical exertion, a strong cough. vaginal examination, visiting the sauna. sexual contact, defecation with a strong natuzhivaniem, etc.
Depending on the type of presentation, the placenta distinguishes the following types of bleeding.
Sudden, profuse and painless bleeding, often occurring at night, when a woman wakes up literally “in a pool of blood” is typical for complete placenta previa. Such bleeding can stop as suddenly as it began, or it will continue in the form of scant excretions.
The onset of bleeding in the last days of pregnancy or during labor is characteristic of incomplete presentation of the placenta.
The intensity of bleeding and the volume of blood loss does not depend on the degree of presentation of the placenta. In addition, bleeding with placenta previa can be not only a symptom of pathology, but also become its complication if it does not stop for a long time.
Given the recurring episodes of bleeding with placenta previa, pregnant women with this pathology almost always have severe anemia. lack of volume of circulating blood (BCC) and low blood pressure (hypotension). These nonspecific signs can also be considered symptoms of placenta previa.
Also the following symptoms are considered indirect symptoms of placenta previa.
Incorrect presentation of the fetus (oblique, transverse, gluteal.
High standing of the bottom of the uterus.
Listening to blood noise in the vessels at the level of the lower segment of the uterus.
What threatens placenta previa – possible complications.
Placental presentation may threaten the development of the following complications.
The threat of termination of pregnancy.
Incorrect fetal placement in the uterus (oblique or transverse.
Pelvic or anterior presentation of the fetus.
Chronic hypoxia of the fetus.
Retarded fetal development.
The threat of termination of pregnancy is caused by recurrent episodes of detachment of the placenta that provokes fetal hypoxia and bleeding. Full placenta previa often ends with premature birth.
Gestosis with placenta previa is due to the impossibility of a full second invasion of the trophoblast into the endometrium, since the mucosa in the lower segment of the uterus is not thick enough and thick to penetrate into it additional villi. That is, a violation of normal growth of the placenta in its presentation provokes gestosis, which, in turn, increases severity and increases the frequency of bleeding.
Fetoplacental insufficiency is due to the fact that the blood supply of the lower segment of the uterus is relatively low in comparison with the bottom or body, as a result of which insufficient blood is supplied to the placenta. Poor blood flow causes insufficient amounts of oxygen and nutrients that enter the fetus and, therefore, do not satisfy its needs. Against the backdrop of such a chronic deficiency of oxygen and nutrients, hypoxia and delayed development of the fetus are formed.
Iron deficiency anemia is caused by recurring periodic bleeding. Against the background of chronic blood loss in women, in addition to anemia, a deficiency of circulating blood volume (BCC) and coagulation factors is formed, which can lead to the development of DIC syndrome and hypovolemic shock in childbirth.
Incorrect placement of the child or his pelvic presentation is due to the fact that there is not enough free space in the lower part of the uterus to accommodate the head, since it was occupied by the placenta.
Placenta previa – principles of treatment.
Unfortunately, there is currently no specific treatment that can change the attachment site and the location of the placenta in the uterus. Therefore, therapy with placenta previa is aimed at stopping bleeding and maintaining pregnancy as long as possible – ideally before the term of delivery.
With placenta previa throughout the entire pregnancy, a woman must necessarily observe a protective regime aimed at excluding various factors capable of provoking bleeding. This means that a woman needs to limit physical activities, do not jump and ride on a jolting road, do not fly on an airplane, do not have sex, avoid stress. do not lift weights, etc. In your free time, you should lie on your back, throwing your feet up, for example, on the wall, on the table, on the back of the sofa, etc. The position of “lying on your back with raised legs” should be taken at any opportunity, preferring to just sit on a chair, in a chair, etc.
After 24 weeks, if bleeding is uneventful and self-stopping, a woman should receive conservative treatment aimed at maintaining the pregnancy until 37 to 38 weeks. Therapy of placenta previa is to use the following drugs.
Tocolytic and antispasmodic drugs, improving the stretching of the lower segment of the uterus (eg, Ginipral. No-sppa, Papaverin, etc.).
Iron preparations for the treatment of anemia (for example, Sorbifer Durules, Ferrum Lek, Tardiferon, Totema, etc.).
Preparations for the improvement of the fetal blood supply (Ascorutin, Kurantil, Vitamin E, folic acid, Trental, etc.).
The most common conservative treatment for placenta prevalence against a background of unwholesome bleeding consists of a combination of the following drugs.
Intramuscular injection of 20 – 25% magnesium in 10 ml.
Magne B6 2 tablets twice a day.
But-shpa 1 tablet three times a day.
Partusisten 5 mg four times a day.
Sorbifer or Tardiferone 1 tablet twice a day.
Vitamin E and folic acid are 1 tablet three times a day.
These drugs a woman will have to take during the entire pregnancy. When bleeding occurs, it is necessary to call an “ambulance” or to get to the maternity home and be hospitalized in the department of pregnancy pathology. In the hospital No-shpu and Partusisten (or Ginipral) will be administered intravenously in large doses to achieve the effect of strong relaxation of the uterine muscles and a good stretching of its lower segment. In the future, the woman will again be transferred to the tablet form, which is taken in smaller, maintenance dosages.
For the treatment of fetoplacental insufficiency and prevention of fetal hypoxia the following agents are used.
Trental is administered intravenously or taken in the form of tablets.
Currantil take 25 mg 2 – 3 times a day for an hour before meals.
Vitamin E take 1 tablet a day.
Vitamin C take 0.1-0.3 g three times a day.
Cocarboxylase is administered intravenously by 0.1 g in a glucose solution.
Folic acid taken internally at 400 mcg per day.
Actovegin take 1 to 2 tablets per day.
Glucose is administered intravenously.
Therapy of fetoplacental insufficiency is carried out by courses during the entire pregnancy. If the use of these drugs can prolong the pregnancy to 36 weeks, the woman is hospitalized in the antenatal ward and the method of delivery is chosen (caesarean section or natural delivery.
If, on presentation of the placenta, a strong, persistent bleeding develops, which can not be stopped for several hours, an emergency cesarean section is performed, which is necessary to save the life of a woman. In such a situation, the fetus is not thinking about the interests of the fetus, since the attempt to preserve the pregnancy against a background of severe bleeding with placenta previa will lead to the death of both the child and the woman. Emergency cesarean section with placenta previa is made according to the following indications.
Repeated bleeding, in which the volume of lost blood is more than 200 ml.
Regular meager blood loss on the background of severe anemia and low blood pressure.
Single-time bleeding, in which the volume of lost blood is 250 ml or more.
Bleeding with full placenta previa.
Childbirth with placenta previa.
With the placenta previa, the birth can be carried out both through natural routes and by cesarean section. The choice of the method of delivery is determined by the condition of the woman and the fetus, the presence of bleeding, and also by the type of presentation of the placenta.
Caesarean section with placenta previa.
Cesarean section with placenta previa is currently performed in 70-80% of cases. Indications for caesarean section for placenta previa are the following: 1. Full placenta previa. 2. Incomplete presentation of the placenta, combined with pelvic presentation or fetal disposition, scars on the uterus, multiple pregnancy, polyhydramnios, narrow pelvis, the age of the pervasive woman over 30 years of age and a history of obstetric anamnesis (abortions, scraping, miscarriages, pregnancy loss and uterine surgery in past); 3. Continuous bleeding with a blood loss of more than 250 ml for any type of presentation of the placenta.
If the listed indications for cesarean section are absent, then with placenta previa, you can lead births through natural ways. Read more about caesarean section.
Childbirth through natural ways.
Births through natural ways with placenta previa can be conducted in the following cases.
No bleeding or stopping after opening the fetal bladder.
Ready for delivery cervix.
Regular contractions of sufficient strength.
Head presentation of the fetus.
In this case, they wait for the independent onset of labor without the use of stimulant drugs. In childbirth, the fetal bladder is opened when the cervix is opened for 1 to 2 cm. If after opening the fetal bladder, bleeding develops or does not stop, then an emergency cesarean section is performed. If there is no bleeding, then the birth continues in a natural way. But with the development of bleeding, an emergency cesarean section is always performed.
Sex and placenta previa.
Unfortunately, sex with placenta previa is contraindicated, as the frictional movements of the penis can provoke bleeding and placental abruption. However, with the placenta previa, not only classical vaginal sex is contraindicated, but oral, anal, and even masturbation, since sexual arousal and orgasm lead to a short but very intense contraction of the uterus, which can also provoke bleeding, placental abruption or premature birth.
Placenta previa – reviews.
Reviews of women who have been pregnant with placenta praevia vary. But in the overwhelming majority of cases, the presentation, revealed in the interval from 20 to 27 weeks of pregnancy at the time of delivery, was eliminated because of the migration of the placenta to the higher sections of the uterine wall. In such women, childbirth and pregnancy, as a rule, proceeded quite safely, as evidenced in numerous reviews on thematic forums. In these cases, women note that placenta previa is not a serious condition.
In relatively rare cases, the placenta did not migrate to the term of labor, and such women were given a cesarean section. Fetching pregnancy in such situations was more difficult, women were more often bothered by bleeding, and they had to behave very carefully so as not to accidentally provoke premature birth or fetal death from acute hypoxia. In such cases, in the reviews of women noted that placenta previa is a serious pathology.
In the overwhelming majority of cases, pregnancy with placenta prevalence resulted in the birth of a normal healthy child, which is also noted by women in thematic forums, urging others not to be afraid and not to worry.