Marginal placenta previa is a pathological attachment of an embryonic organ that provides a connection between the mother and the fetus, in which there is a partial overlap of the internal pharynx of the uterus (no more than a third of it). Clinically, the disease manifests itself with bleeding of varying intensity, not accompanied by discomfort. It is possible to identify the marginal presentation of the placenta with the help of a planned ultrasound in the second trimester or when pathological signs occur. Treatment involves hospitalization, bed rest, symptomatic therapy. A wait-and-see tactic is shown before the expected delivery period, provided that the woman and fetus are in normal condition.
General information
Marginal placenta previa is a pathology of pregnancy, accompanied by abnormal attachment of the placenta and partial overlap of the internal pharynx of the uterus. This condition is dangerous both for the woman herself and for the fetus. Marginal presentation of the placenta in the early stages is associated with less risk, since with the subsequent growth of the baby and stretching of the myometrium, it can shift and acquire the correct location. Otherwise, there is a possibility of compression of the feeding vessels, partial blocking of oxygen and nutrients access to the fetus, which can cause its hypoxia and even stillbirth.
Marginal presentation of the placenta can lead to its detachment. This is due to the fact that the lower segment of the uterus has less ability to stretch. Also, marginal placenta previa often provokes massive bleeding during childbirth. Such an outcome is possible during natural childbirth, if there was a sharp separation of the membranes as a result of the passage of the fetus through the birth canal. In obstetrics, marginal placenta previa occurs mainly in repeated pregnancies. Pathology requires careful monitoring, since in about 25% of cases it is accompanied by stillbirth.
Causes
The marginal presentation of the placenta may be due to abnormal attachment of the trophoblast during implantation or anatomical features of the myometrium. In the latter case, a violation of the structure of muscle fibers in the uterine wall occurs against the background of inflammatory changes, the consequences of sexual infections. Marginal placenta previa is more often diagnosed with thinning of the myometrium, provoked by frequent curettage and abortions. Also, the cause of abnormal attachment of the trophoblast may be deformations of the uterus caused by benign tumors or resulting from congenital pathologies.
Marginal placenta previa often develops in women with concomitant diseases of the internal organs, in particular, in the pathology of the cardiovascular system. Due to insufficient blood circulation and stagnation in the pelvis, the placenta cannot fully attach. In addition, marginal placenta previa is possible against the background of abnormal embryo development immediately after fertilization. A similar outcome is observed with the belated appearance of the enzymatic functions of the trophoblast. As a result, it attaches to the myometrium later than it normally does, staying in the lower part of the uterus.
Classification
Marginal presentation of the placenta can be of two types, depending on the place of its attachment:
Localization along the anterior wall is the most dangerous variant of the course of pathology. With the marginal presentation of the placenta of this type, there is a high risk of its mechanical damage with subsequent detachment due to the physical activity of the woman, the movements of the baby, against the background of severe stretching of the uterus in the third trimester of pregnancy. Despite this, when placing an embryonic organ on the anterior wall of the uterus, there is a possibility of moving it upwards.
Attachment along the back wall is a more favorable option for marginal placenta previa. It is accompanied by a lower risk of complications during gestation and childbirth for the mother and baby.
Both types of abnormalities are a pathology of pregnancy and require mandatory supervision by an obstetrician-gynecologist.
Symptoms and diagnosis
Marginal placenta previa has a characteristic symptomatology – the appearance of bloody discharge without deterioration of general well-being. Often this pathological sign occurs at rest or at night. As for the timing of embryogenesis, the marginal presentation of the placenta manifests itself mainly at 28-32 weeks. It is during this period that the uterus is characterized by increased activity due to the preparation of the myometrium for the upcoming birth. Somewhat less often, abnormal discharge is observed already at the beginning of the second trimester. The volume of bleeding can be different and depends on the degree of vascular damage.
With marginal placenta previa in the third trimester of pregnancy, the release of blood can be provoked by physical exertion, sexual intercourse, fetal movement and other factors that provoke rupture of nutrient vessels. The appearance of this sign is possible even with a gynecological examination. Sometimes the marginal presentation of the placenta is combined with the threat of miscarriage. With this combination, there is discomfort in the lower abdomen, uterine hypertonus. With systematic bleeding, pregnant women with this diagnosis develop iron deficiency anemia. In such cases, there is increased fatigue, weakness. On the part of the fetus, growth and development may slow down, hypoxia due to insufficient intake of nutrients. Marginal presentation of the placenta is often combined with an incorrect fetal position, which can be oblique or transverse.
A preliminary diagnosis is made based on the patient’s complaints of spotting in the absence of pain. Another characteristic feature of the abnormal location of the embryonic organ is the high standing of the uterine floor, which does not correspond to the period of embryogenesis. It is possible to confirm the marginal presentation of the placenta with the help of ultrasound. During the scanning process, a specialist can accurately visualize the localization of the placenta and the degree of overlap of the uterine pharynx, determine the condition of the child and assess possible risks for the woman and fetus.
Treatment
Treatment of marginal placenta previa depends on the identified symptoms, the period of embryogenesis, as well as the condition of the expectant mother and fetus. If the diagnosis is made only on the basis of ultrasound scanning and bleeding is not observed, it is possible to monitor the patient’s condition on an outpatient basis. Hospitalization is indicated if the marginal presentation of the placenta is accompanied by secretions of any volume of blood. In this case, careful monitoring in the hospital is required. Women with such a diagnosis are assigned complete rest, it is recommended to exclude sexual contact and stress. It is necessary to wear a bandage. In the second trimester, a special physical therapy for pregnant women sometimes helps to correct the placenta location.
With the marginal presentation of the placenta, anemia often develops due to systematic blood loss. Therefore, pregnant women are shown a diet enriched with foods high in iron. The diet should include red fish, offal, buckwheat, beef, apples. Pregnancy management with marginal placenta previa involves a protective regime in order to achieve the expected date of birth and the birth of a full-term baby. Also, patients with a similar diagnosis are prescribed medications taking into account the general condition and concomitant pathologies.
With marginal placenta previa, symptomatic drug therapy is performed. With hypertonicity of the uterus, tocolytics and antispasmodics are used, iron-containing drugs are prescribed to eliminate anemia. Vitamin complexes can be used to maintain the general condition of the patient and fetus. Sometimes, with marginal placenta previa, it is advisable to use sedatives. According to the indications, antiplatelet agents are introduced, the dosage of drugs is calculated by the doctor in order to avoid negative effects on the baby.
If the marginal presentation of the placenta is accompanied by massive bleeding, delivery is carried out regardless of the period of embryogenesis by emergency Caesarean section. In the case of a full-term pregnancy, natural childbirth is permissible under the condition of maturation of the cervix, active labor, good condition of the patient and fetus. When the cervix is opened by 3 cm, an amniotomy is performed. Oxytocin is administered to prevent bleeding. If, with marginal presentation, the placenta significantly overlaps the uterine pharynx or childbirth through a natural channel is impossible, a caesarean section is indicated.
Prognosis and prevention
The prognosis for marginal placenta previa is favorable. With timely diagnosis and compliance with medical recommendations, patients manage to deliver a fetus up to 38 weeks and give birth to a completely healthy baby. Marginal presentation of the placenta can provoke the development of bleeding in the postpartum period. To prevent it, specialists use intravenous administration of oxytocin. The prevention of pathology consists in the treatment of gynecological diseases even before conception, the exclusion of abortions and invasive interventions on the uterus. After pregnancy, you should follow the doctor’s recommendations, give up physical activity, avoid stress.
