Blighted ovum is a type of frozen pregnancy in which, after fertilization and implantation, the egg does not develop into an embryo, but an empty fetal egg remains. Pregnancy does not progress, so signs of toxicosis and other early symptoms in the form of drowsiness, pain in the mammary glands, mood swings gradually disappear. Blighted ovum is diagnosed by the results of ultrasound of the pelvic organs at the 5th week of pregnancy, can be confirmed by blood tests for hCG, alpha-fetoprotein. Specific treatment consists in removing the remains of the embryo by medication or by vacuum aspiration.
O02.0 Dead fetal egg and non-bubble drift
Blighted ovum, or non-bubble drift, may be a consequence of the initial absence of an embryo in the uterine cavity or its death in up to 5 weeks. In women with a diagnosed pregnancy, on average, one in five ends in spontaneous abortion or stops development. Independent emptying of the uterine cavity occurs in 53% within 2 weeks after diagnosed blighted ovum. If the remains of the fetal egg are not removed at this time, then 2.5% will experience bleeding or infectious and inflammatory complications that require curettage and subsequent treatment. The fetal egg with blighted ovum may linger in the uterus for more than 2 weeks, but at the same time symptoms appear that require surgical assistance.
Causes of blighted ovum
The exact causes of this pathology are difficult to establish, they are assumed retrospectively based on additional symptoms and examination of the woman. The cause of blighted ovum may be diseases of the mother, as well as the action of various external and internal pathological factors. The main risk of pregnancy loss occurs in a short period, when the first division of blastomeres occurs, implantation of the embryo into the uterine mucosa. The causes of blighted ovum may consist of the following disorders:
- Genetic and chromosomal abnormalities. They are the main cause of pregnancy loss in the early stages. Chromosomal abnormalities occur both at the stage of fertilization when two sperm cells enter the egg, and at the next stages of cell division. The older the age of the mother, the higher the chance of chromosomal aberrations.
- Pathology of the endometrium. The cause of blighted ovum may be chronic endometritis and endometrial regenerative plastic insufficiency syndrome. With chronic inflammation, immune changes occur that reduce the receptive properties of the mucous membrane, lead to the slugging of erythrocytes in the emerging chorionic villi and the formation of microthrombs.
- Anatomical disorders. The prerequisite may be congenital malformations of the uterus or acquired structural changes that are caused by synechiae, myomatous nodes, polyps. These pathologies are accompanied by signs of hormonal disorders, changes in endometrial receptivity.
- Diseases of the coagulation system. Thrombophilia, which occurs against the background of antiphospholipid syndrome or hemostasis insufficiency, leads to the formation of blood clots in the interstitial space. The nutrition of the embryo is disrupted, which causes its death at the beginning of pregnancy.
Blighted ovum is associated with the death of the embryo and a violation of the inertia of the uterus, which leads to a delay in the cavity of an empty fetal egg. The main causes of myometrial areactivity are as follows:
- Tight attachment of the embryo. Deep invasion of chorionic villi occurs with structural and functional inferiority of the endometrium. Another reason is incomplete pre–gravidar transformation in the implantation zone and high proliferative activity of chorionic villi.
- Immune deficiency. The tissues of the embryo are half foreign to the mother’s body, so normally, with the participation of progesterone, immune rejection reactions are suppressed. The reasons for the preservation of the fetal egg in blighted ovum are associated with the immunological areactivity of the myometrium to the products of conception.
- Violation of contractile function. Rejection of an empty egg does not occur in chronic inflammatory diseases of the uterus due to a violation of the formation of receptors for uterotonic substances. A common cause is biochemical metabolic defects in uterine tissues.
- Lack of folate. Folic acid is involved in cell DNA division. With its deficiency in the early stages of pregnancy, there is a violation of the divergence of chromosomes, their incorrect location. Also, with a lack of folates, sensitivity to radiation exposure increases.
On the 7-8 day after fertilization, the embryo is implanted into the uterine wall, the trophoblast actively produces hCG, which is necessary to preserve pregnancy. By the 3rd week of development, extra–embryonic organs are formed in the embryo – chorion, yolk sac and amnion. A little later, the heart begins to beat, but with the help of an ultrasound machine, this can be noticed after 5 weeks of gestation. If there is a violation of blood flow at the site of implantation, the embryo dies and is gradually reduced. But the fetal vesicle continues to be visualized under the influence of a persistent plume of high pregnancy hormones. If the contractility of the uterus is violated, its rejection and expulsion does not occur.
Morphological examination of the endometrium after curettage in blighted ovum shows that the decidual layer of cells is dystrophically altered. It often reveals lymphoid infiltration, focal edema of the stroma, enlarged glands with flattened epithelial cells. Chorionic villi increase, the epithelium lining them becomes thinner and is located in a single layer of synticiotrophoblast. Cytotrophoblast is absent in places.
Blighted ovum is classified according to the results of ultrasound examination, which allows you to determine the size of the fetal egg and its contents. The size of the uterus does not affect the type of blighted ovum, but is taken into account when determining the gestation period. There are two types of embryo absence:
- Type 1. The average diameter of the fetal egg is 2-2.5 cm, the embryo is not visualized. The size of the uterus corresponds to 5-7 weeks of pregnancy, which does not meet the deadline for the first day of the last menstruation. With dynamic observation, there is no increase in size.
- Type 2. The fetal egg continues to grow, but there is no embryo. Sometimes its remains are observed in the form of a thin hyperechoic strip. Blighted ovum of this type can persist up to 11 weeks, the egg reaches a size of 4.5-5 cm.
Symptoms of blighted ovum
With a normally developing pregnancy by 5-6 weeks, many signs of gestation are present: symptoms of toxicosis, breast swelling, drowsiness or insomnia, mood swings. During the formation of blighted ovum, a pregnant woman may notice that at some point she began to feel better, morning sickness disappeared, there is no aversion to smells and hypersalivation. Normal appetite is restored. Then the mammary glands lose soreness and hypersensitivity, become soft. But these signs may not always indicate blighted ovum. The same symptoms are characteristic of a frozen pregnancy.
Women who do not turn to a gynecologist in a timely manner with signs of pregnancy or their disappearance may face serious complications. With the preservation of an empty fetal vesicle in the uterus for up to 2 weeks or more, an inflammatory reaction occurs, symptoms of acute endometritis appear. The temperature rises, serous-mucous secretions appear from the vagina, signs of intoxication are bothering – weakness, headache. In the absence of treatment or untimely onset, acute inflammation can spread to the muscle layer, parotid tissue, and in severe cases lead to peritonitis. If treatment has not been carried out, chronic endometritis develops.
A sign of rejection of the remains of the embryo from the uterus is the appearance of bloody discharge from the genital tract. But with insufficient contractility of the uterus, hemostasis disorders, bleeding develops. It cannot be completed on its own, therefore medical assistance is required. The consequence of bleeding is infection of the uterine cavity, anemia. Blighted ovum is complicated by subsequent habitual miscarriage, secondary infertility.
Examination and choice of treatment method for blighted ovum is carried out by an obstetrician-gynecologist. Physical examination does not provide accurate information about the pathology, laboratory methods are also non-specific. The most accurate data can be obtained with a vaginal ultrasound of the pelvis. The survey algorithm includes:
- Gynecological examination. Signs of pathology are not always possible to notice, sometimes with a two-handed examination, a lag in the size of the uterus, its softening can be determined. The addition of inflammation is characterized by the appearance of serous-succulent discharge from the cervix.
- Laboratory tests. hCG in the blood drops 6-8 times below the norm for gestation. Alpha-fetoprotein increases by 1.5 times or more, but is not a sign of blighted ovum alone, similar changes occur during frozen pregnancy. Trophoblastic glycoprotein decreases by 6-18 times, which indicates the death of syncytiotrophoblast cells. The concentration of progesterone may remain at the same level, and estrogens decrease.
- Instrumental methods. Informative ultrasound with a vaginal sensor. Signs of blighted ovum are a fetal egg of 25 mm or more and the absence of an embryo in it. If a heartbeat is not detected after 2 weeks with repeated ultrasound, then blighted ovum is diagnosed.
For the correct evaluation of the results, ultrasound examination is carried out in dynamics. If the fetus does not have a heartbeat at 5 weeks, it is impossible to say unequivocally that blighted ovum has been determined. The absence of a yolk sac is an unfavorable prognostic sign that corresponds to a possible anembryonic pregnancy.
Treatment of blighted ovum
Treatment is aimed at evacuation of fetal egg remains from the uterine cavity. This can be done medicamentally and surgically. The latter is used more often, but it is associated with an additional risk of infection and the addition of complications. WHO recommends using medical abortion as the main method of treating blighted ovum.
Medical termination of gestation is carried out with symptoms of blighted ovum up to 83 days of pregnancy. Mifepristone and misoprostol are consistently used for the procedure. The dosage of the latter is selected individually and depends on the gestation period for the last menstruation. Bleeding, which means the release of the remains of the embryo, occurs on the second day. A woman should come to an appointment 14 days after taking the last pill to assess the general condition and effectiveness of the procedure.
Medical abortion has few contraindications. It can be used for infections of the genital tract without prior sanitation. The method is not recommended for bronchial asthma, the presence of pathologies of the cardiovascular system, blood clotting disorders and in women who smoke. Complications of medical abortion may include pain syndrome, bleeding and incomplete abortion, which will require the use of surgical methods of treatment.
Vacuum aspiration is considered to be the optimal and less traumatic method among surgical methods. With blighted ovum, it can be used up to 12 weeks of pregnancy, because the fetal egg remains small. Before the procedure, it is necessary to examine the smear for the degree of purity of the vagina. If there are signs of inflammation, sanitation is carried out by local means. Vacuum aspiration is performed on an outpatient basis, hospitalization in the department of gynecology is not required. After the procedure, there is a possibility of infectious complications, bleeding and preservation of the remains of embryonic tissues, which may require curettage.
For curettage of the uterine cavity, a woman is hospitalized in the gynecological department after a preliminary examination. The procedure is performed under general anesthesia and requires the supervision of medical staff for several days after it. In the postoperative period, antibiotic prophylaxis is prescribed to reduce the risk of infectious complications, uterotonics to improve uterine contractility.
A single case of blighted ovum does not pose a danger, but if it is repeated or another type of gestation interruption in a short period of time, a thorough examination and rehabilitation is necessary. Most women have pronounced symptoms of chronic endometritis or its latent course is observed. Therefore, broad-spectrum antibiotics are prescribed.
Anti-inflammatory drugs, enzymes, immunomodulators are used to correct metabolic and functional disorders in the endometrium, and physiotherapy courses are prescribed. Combined oral contraceptives are used to restore hormonal regulation for 3-6 months. Planning a new pregnancy is carried out after careful pre-pregnancy preparation.
Prognosis and prevention
The prognosis is favorable for a woman’s life and the subsequent realization of reproductive function. After the restoration of the endometrium and the elimination of possible causes of pathology, conception can be planned. To prevent blighted ovum, it is necessary to beware of the effects of external adverse factors, avoid the use of toxic substances, alcohol, smoking. If sexual infections are suspected, they need to be treated in a timely manner. Women should start taking folic acid 2 months before conception and continue the course until the end of the first trimester.