Placental abnormalities are violations of the normal localization, attachment or shape of the placenta. They may be asymptomatic, characterized by signs of fetoplacental insufficiency from the second trimester of pregnancy, manifested by the threat of premature birth or bleeding. Diagnosis is carried out according to ultrasound, fetometry and fetal cardiotocography. No specific treatment has been developed. Therapy is aimed at maintaining blood flow, eliminating signs of hypoxia and prolonging pregnancy. According to the indications, a manual separation of the placenta, hysterectomy is performed after childbirth.
Placental abnormalities occur with varying frequency. Low placentation, placenta previa in the third trimester is observed in 3% of pregnant women. Tight attachment of the afterbirth, increment to the myometrium is more common in pregnant women with scars on the uterus, who have undergone a large number of abortions and curettage, with high parity of labor. In recent decades, there has been an increase in the number of afterbirth increments by 50 times, which is associated with an increase in indications for cesarean section. Placental abnormalities lead to an increase in the frequency of bleeding in the postpartum and postpartum period, complications from the fetus.
Causes of of placental abnormalities
Placental anomalies occur as a result of compensatory and adaptive reactions in pathological conditions of the endometrium and myometrium. Ingrowth, low placentation and shape change occur for the same reasons. Most often , the development of an anomaly is observed in the presence of the following predisposing factors:
- Pathology of the endometrium. Inflammatory diseases in the anamnesis, frequent abortions potentiate dystrophic changes in the mucous membrane, violation of the receptive properties of the endometrium. In search of the optimal implantation site, the blastocyst can descend from the bottom of the uterus to the lower segment, and the placenta can attach tightly.
- Dystrophic changes in the uterus. With fibroids, there are blood flow disorders that provoke deep penetration of chorionic villi. In women after cesarean section, an incomplete basal layer of the mucosa forms at the site of the scar, which leads to deep ingrowth of the placenta. If, due to lack of nutrition, a part of the chorionic villi dies, a dicotyledonous afterbirth is formed.
- Excessive activity of the chorion. Deep ingrowth of villi is associated with the release of a large amount of chorionic gonadotropin by the embryo. An increase in hormone levels in the first trimester may be associated with chromosomal abnormalities of the fetus, normally observed during pregnancy with twins.
- Hormonal disorders. The growth of chorionic villi is restrained by estrogens. With hormonal insufficiency, they grow into the muscle layer of the uterus and the formation of an increment of the placenta.
- Kiss1 is a gene. Discovered in 1999, it is detected in many malignant tumors, as well as syncytiotrophoblast cells. The gene stimulates deep invasion of syncytio- and cytotrophoblast cells into the myometrium. The activity of the gene increases when progestogens are used to preserve pregnancy in the early stages.
Placental abnormalities are the results of uterine pathologies that occurred before pregnancy. Inflammatory processes and dystrophic changes lead to insufficient vascularization of certain areas of the decidual membrane. This causes the death of some chorionic villi at an early stage of gestation. Areas of thinning of the placenta and various defects are formed. With the complete death of the villous chorion, foci without placental tissue (the terminal placenta) are formed. In the presence of vessels going to the side, an additional lobule is revealed, which is located at a distance from the edge of the children’s place.
In the uterine floor, the blood flow is increased due to the branches of the ovarian artery. But in cases when the blastocyst is implanted in the lower segment, it experiences a shortage of blood supply, which potentiates a deep invasion of chorionic villi into the myometrium, so low placentation may be accompanied by placenta ingrowth. Sometimes presentation is associated with an excessive increase in the size of the afterbirth during multiple pregnancies. Histological examination shows premature involution-atrophic changes caused by insufficient blood flow and overgrowth of the lower segment.
A unified classification of afterbirth anomalies has not been developed. Pathology is conditionally divided into three types, which are pathogenetically related. Due to the general mechanism of development, various anomalies can be combined, which worsens the prognosis and the course of pregnancy. Specialists in the field of obstetrics distinguish the following variants of placental abnormalities:
- Localization violations. They include low placentation and placenta previa. Complete presentation is diagnosed at 12 weeks, practically not eliminated on its own. Low placentation by the 3rd trimester may be replaced by normal attachment due to an increase in the volume of the uterus and migration of the placenta.
- Attachment anomalies. There are dense attachment and increment of the placenta. End-to-end germination with invasion of the chorion into neighboring organs is rarely observed. It can also be diffuse (the entire fetal site is not separated from the uterine wall) or focal (ingrowth occurs in a certain area).
- Shape anomalies. The placenta, consisting of two parts, is called bipartite. With excessive thinning, the filmy type is diagnosed. The cingulate appearance is characterized by the formation of a shaft along the edge of the fetal site, which is a site of circular detachment or inflammation with hyaline deposition.
This condition is not always accompanied by clinical symptoms. With a dicotyledonous and terminal variety of the fetal site, as well as an additional lobule, there are no signs of pathology during pregnancy, difficulties arise in childbirth. The additional lobule can come off and remain in the uterine cavity. Hypotension is determined, complicated by bleeding in the early postpartum period. Bleeding in the third period of labor develops with a tight attachment of the placenta. There are no signs of separation of the afterbirth, and the techniques that accelerate this process are ineffective.
Low placentation is accompanied by symptoms of the threat of interruption. A woman periodically feels pulling pains in the lower abdomen, the tone of the uterus increases. With full presentation from the 2nd trimester, periodic spotting, sometimes moderate spotting from the vagina is observed. The danger is massive bleeding, which quickly leads to acute fetal hypoxia and hemorrhagic shock in a pregnant woman.
Pathology of the afterbirth sometimes provokes the development of placental insufficiency and chronic fetal hypoxia. The child lags behind in growth, is born with a low weight, tolerates the period of adaptation worse. Bleeding during placenta previa can begin at any stage of pregnancy. With untimely help, it becomes the cause of intrauterine fetal death, and the mother has hemorrhagic shock and DIC syndrome. Sometimes attachment abnormalities become an indication for extirpation of the uterus.
Screening ultrasound examination is carried out at 11 weeks of pregnancy, the technique allows you to identify the first signs of an anomaly. The results of repeated mandatory examination at 21 and 32-34 weeks indicate the progression of pathology or a decrease in its manifestations. Diagnosis of the condition is carried out by an obstetrician-gynecologist and is based on the data of the following methods:
- Physical examination. With fetoplacental dysfunction, the discrepancy between the size of the abdomen and the gestation period may be determined. Placenta previa is indicated by soft spongy tissue above the cervix. When examined in mirrors, blood clots or liquid secretions may be detected, which are a sign of bleeding.
- Ultrasound of the uterus. The pathological location is diagnosed already at the end of the 1st trimester, but it is confirmed only with the last study in the 3rd trimester. Full presentation is indicated by the location of the afterbirth immediately above the inner throat of the neck. Attachment disorders are determined by abnormal lacunar blood flow in the thickness of the myometrium.
- Fetometry of the fetus. The size of the fetal body parts is examined using ultrasound. The insufficiency of the fetoplacental complex manifests itself in the lag of the length of the femur, shoulder, coccygeal-parietal size and head. The circumference of the abdomen may decrease. The parameters can decrease uniformly (symmetrical type of developmental delay) or unevenly (asymmetric type).
- Cardiotocography. The fetal heart rate, its changes during stirring, uterine contractions are evaluated. With chronic hypoxia, the basal rhythm decreases, the number of accelerations increases, the number of decelerations increases, and variability becomes low. The severity of hypoxia is assessed by a point system.
Treatment of placental abnormalities
It is impossible to influence anomalies of localization, shape or attachment by medication or other means, therefore treatment is aimed at prolonging pregnancy, choosing the optimal term and method of delivery. It is necessary to ensure the improvement of fetal nutrition and minimize the effects of hypoxia. Attachment abnormalities require emergency surgical care.
In case of pathological localization detected at the first screening ultrasound, medications that improve placental blood flow are used. With an increase in the tone of the uterus, tocolytic therapy with a solution of magnesia is carried out, a course of vitamin B6 in combination with magnesium is prescribed. Spotting secretions from the genital tract during the presentation of a child’s place is an indication for emergency hospitalization in the department of pathology of pregnant women.
Conservative therapy after childbirth can be used with an increment of the afterbirth, which could not be eliminated manually. A prerequisite for medical treatment is the absence of bleeding. Cytostatics from the group of antimetabolites and folic acid inhibitors are used. Medications cause independent resorption of the afterbirth and allow you to save the uterus, but do not affect hemostasis indicators.
Surgical care is necessary for such anomalies as bleeding caused by placenta previa, tight attachment or true increment, hypotonic bleeding with an additional lobule. Presentation accompanied by bleeding is an indication for an emergency caesarean section, regardless of the gestation period. In other cases, the following methods are used:
- Manual separation of the afterbirth. It is used in the absence of signs of independent separation, as well as with uterine hypotension and bleeding in the last period of labor. The manipulation is performed under general anesthesia in the delivery room in the presence of an anesthesiologist-resuscitator.
- Surgical removal of the placenta. After preliminary ligation of the uterine vessels, embolization of the uterine arteries or the imposition of compression sutures on the uterus, the placenta separates from the wall. Uterine devascularization avoids massive bleeding.
- Hysterectomy. In case of unsuccessful attempts to separate the afterbirth with attachment abnormalities and continued bleeding, the issue of removing the uterus with the preservation of appendages is resolved. The intervention is performed under endotracheal anesthesia.
Prognosis and prevention
Anomalies in the shape of the baby’s place rarely worsen the prognosis of pregnancy, sometimes they are diagnosed accidentally after childbirth. In case of attachment abnormality, medical supervision is necessary to prevent complications. Prevention consists in the refusal of abortions or the use of medical methods of termination of pregnancy. Women are recommended to use barrier methods of contraception to protect against infections, treat inflammation of the genitals in a timely manner. Caesarean section should be performed strictly according to indications.