The concept of «Undeveloped or frozen pregnancy» includes two clinical conditions:
– dead fetal egg, anembryony (the synonym is anembryonic pregnancy), which is an empty embryonic sac due to aplasia or early resorption of trophoblast
– a failed miscarriage (missed abortion) is early intrauterine death of the fetus and fetal retention in the uterine cavity.
According to various researchers, every fifth desired pregnancy spontaneously terminates, and in 88.6% of cases, it happens according to the type of failed miscarriage (Kulakov U., 2002).
Also, despite an intensive study of this complication of pregnancy, in 26–66% of cases, the cause of an undeveloped pregnancy remains unclear.
The causes of an undeveloped pregnancy are diverse, they are often combined. The developmental plateau of the embryo may be conditioned by both genetic (immunological incompatibility, gene or chromosomal mutations) and environmental factors (maternal morbidity, chemical or physical effects on the mother and fetus body). Many of these factors are teratogenic for the embryo and can lead to its damage regardless of the time of exposure.
A distinction is made between sporadic (the single episode of a non-developing pregnancy in the anamnesis) and the habitual non-developing pregnancy (the presence of two or more undeveloped pregnancies).
To prevent interruption of pregnancy, it is advisable to identify risk factors for the occurrence of this complication and, if possible, eliminate them. Obstetrician-gynecologists attribute the following positions to these factors:
It is very important to note that the dominant causes in the development of undeveloped pregnancy are infection, genetic and hormonal disorders. At the same time, autoimmune (APS) are not significant. The risk of the evolvement of non-developing pregnancy increases many times with a combination of two or more factors. In 22.2% of cases, a mixed genesis of pregnancy interruption is detected.
Besides, periodic fluctuations in the incidence rate of an undeveloped pregnancy indicate the seasonal nature of this pathology. A clear relationship between the death of the fetal egg and the season of conception was revealed. The maximum occurrence of a non-developing pregnancy falls on the periods corresponding to the conception at the «junctions» of ovulatory and anovulatory cycles, i.e. during the seasons of the year (March, May, September, December).
Typical clinical signs of an undeveloped pregnancy are, as a rule, prolonged smearing bloody spotting from the genital tract, aching or cramping pains in the lower abdomen. These symptoms appear 2–6 weeks after the cessation of the development of the ovum. By this time, in 80% of cases, a discrepancy between the size of the uterus and the expected gestational age is revealed. A decrease in the size of the uterus is more often detected during fetal death in the 1st trimester of pregnancy. Up to 12 weeks this can occur due to resorption of the ovum, in case of longer periods – as a result of absorption of amniotic fluid, maceration, dehydration and wrinkling of the fetus.
A reliable diagnosis of an undeveloped pregnancy in 98–100% of cases is established through ultrasound examination in combination with clinical data.
Treatment of women with undeveloped pregnancy presents certain difficulties. Undoubtedly, active intervention is justified, because a long delay of a dead fetal egg in the uterus can lead to the development of serious complications. Therefore, when confirming the diagnosis of undeveloped pregnancy, after appropriate preoperative preparation, the fetal egg should be removed from the uterus.
Taking into account the priority role of the infectious factor, in the post-abortion period, differential therapy involving a combination of antiviral and antibacterial drugs together with antimycotic drugs is mandatory. After completion of antiviral and antibacterial therapy, hormonal disorders are corrected according to indications.
Since embryos that have stopped at an early stage of embryogenesis, malformations and chromosomal abnormalities are much more common than in the perinatal period. It is advisable to consult family couples who have undeveloped pregnancies in their anamnesis with specialists in medical genetic counseling.
Based on the foregoing, for the desired pregnancy to proceed without complications and end with the birth of a healthy baby, the pregnancy must be planned. Pregnancy planning means preparing for pregnancy, including examining both parents, primarily for infection, correcting existing hormonal disorders, sanitation of chronic foci of infection, treating extragenital diseases, and taking medications to prevent the development of fetal malformations.
Obstetrician-gynecologist of the highest category,
S. Kandrašova (Head of the ultrasound department)
The article uses data from the state institution Medical and genetic scientific center of RAMP, department of obstetrics and gynecology of RMAPE