Fibroids during pregnancy is a benign volumetric formation of the myometrium that occurred before the onset of gestation and can complicate its course. Most patients have no clinical symptoms. With large neoplasms, the disease can manifest itself as heaviness in the lower abdomen, constipation, increased defecation and urination, swelling of the legs and genitals. It is diagnosed by ultrasound of the uterus. For conservative treatment of myomatous nodes, antispasmodics, tocolytics, antiplatelet agents are used. In the presence of indications, conservative myomectomy may be performed.
General information
Uterine fibroids are detected in 0.2-6% of pregnant women, while more than 2/3 of patients are over the age of 30, half of them have their first pregnancy. In recent years, there has been a rejuvenation of the disease with increasingly frequent detection of myometrial tumors in patients aged 27-29 years. Most young patients have a burdened heredity, according to research, if a woman was found to have fibroids in late reproductive age or premenopause, her daughter usually falls ill 10-15 years earlier. In 10-40% of cases, the course of gestation and childbirth in the presence of myomatous nodes is complicated, in the most severe cases, the loss of the fetus and uterus is possible.
Causes
Specialists in the field of gynecology offer a number of theories of the formation of myomatous nodes, but today the causes of the development of fibroids in non-pregnant and pregnant women continue to be clarified. According to many authors, predisposing factors to the onset of neoplastic processes in the myometrium, regardless of the presence of gestation, are:
- Dishormonal disorders. An imbalance of sex hormones is observed in ovarian diseases (chronic oophoritis, adnexitis, cysts, endometriosis), disorders of hypothalamic-pituitary regulation, endocrine pathology (diabetes mellitus, hypothyroidism, autoimmune thyroiditis, adrenal diseases), overweight.
- Post-traumatic changes in myometrial fibers. In patients who have previously undergone abortions, diagnostic curettage, operations on the uterus, and other invasive procedures, it is possible to increase the proliferative activity of the cells of the muscle layer. The predominance of neogenesis processes over apoptosis contributes to the formation of smooth muscle nodes (fibroids).
- Burdened heredity. The role of genetic mutations in the development of pathology is proved. Chromosomal aberrations are detected in 30-73% of patients. Myomatosis is more often detected with point aberrations of the ESR1, ESR2 genes, in which the sensitivity of estrogen receptors changes, and MED12, which affects the synthesis of a protein that regulates the activity of other genes.
An additional risk factor in pregnant women is a change in the level of sex hormones in the local blood flow of the uterus, aimed at maintaining gestation. According to observations, in the first 8 weeks of gestational age, hyperplasia and hypertrophy of myometrial cells increase, which is accompanied by tumor growth. Disorders at the central level of neurohumoral regulation associated with a psychological reaction to pregnancy and more pronounced in anxious and hypochondriacal women may play a certain role.
Pathogenesis
A key link in the formation and growth of fibroids during pregnancy is a violation of the processes of proliferation, apoptosis and associated angiogenesis. According to the most common theory, the increased expression of estrogen receptors of myocytes (ER-α and ER-β) in the first weeks of pregnancy stimulates the proliferation of smooth muscle cells, which begin to form microscopically and macroscopically determined nodules. Further tumor growth depends less on hormonal stimulation and is regulated by its own autocrine mechanisms. An important feature of the pathogenesis of fibroids in pregnant women and possible complications of the disease is the inhibition of cellular node hyperplasia and accelerated destruction of muscle cells in their central zone, starting from the 8th week of gestation. The volume of the neoplasm may remain the same due to edema caused by disorders of lymph and hemodynamics.
When the placenta is placed over a large intramural neoplasm, pathological processes during pregnancy occur not only in the tissues of fibroids, but also in the subplacental bed. There is less tortuosity and shortening of spiral vessels, a decrease in the number of anastomoses, and an increase in the volume of the interstitial fibrinoid. The villi partially stop in development, remain pathologically immature. Compensatory mechanisms are represented by enhanced angiomatosis of terminal villi, an increase in the number of syncytial kidneys. Thrombosis and infarctions of the placental bed, hypoplasia of the placenta with the development of fetoplacental insufficiency are possible. Thinning of the myometrial layer between the decidual membrane and the centripetally growing myoma increases the likelihood of true ingrowth of chorionic villi into the uterine wall.
Classification
During pregnancy, the forms of uterine fibroids are usually systematized taking into account the localization of the node, its placement in the muscle layer, the characteristics of the base of subserous and submucous tumors, the number and size of neoplasms. It is these factors that most affect the development of gestation and the risk of complications. According to the location relative to the myometrium, obstetricians and gynecologists distinguish the following types of fibroids:
- Submucous. The myomatous node is located under the endometrium and grows into the uterine cavity. With submucosal fibroids, placentation processes are most often disrupted. Large tumors exert pressure on the fetus and its membranes, which can lead to termination of pregnancy and deformations of the child’s skeleton.
- Intramural. The neoplasm is formed in the middle part of the muscle layer. The effect on pregnancy usually has a large node size. The main complications are associated with pathological changes in the subplacental site, placenta, less often with the pressure of neoplasia on the growing fetus.
- Subserous. The tumor develops from the outer part of the myometrium, its growth is directed towards the abdominal cavity. Gestation is rarely affected. The displacement of the fibroid located on the leg increases the risk of twisting of the neoplasm with subsequent necrosis. Large neoplasias squeeze neighboring organs.
In 5% of cases, fibroids are localized in the cervix, which leads to cervical insufficiency in pregnant women. Clinically significant is the division of fibroids into single and multiple, small and large (from 5 cm), on a leg or a wide base. A more serious prognosis is noted in women with several nodes, large tumors or neoplasms on the leg. The wide base of submucous fibroids worsens the course of pregnancy only when the placenta is located above it. The division of neoplasias by histological structure into leiomyomas, fibromyomas, fibroids usually has no prognostic value during gestation.
Symptoms
In the absence of complications, the disease in pregnant women, especially at the initial stages, is asymptomatic and is detected accidentally during routine ultrasound screening. In the presence of large fibroids, there may be a feeling of discomfort, pressure, heaviness in the lower abdomen, inconsistency of the circumference of the abdomen with the term of pregnancy. Increased urination, constipation or more frequent urge to defecate, swelling of the legs, external genitals, the appearance of hemorrhoids caused by compression of a subserous tumor of the bladder, rectum and main veins, most patients are associated with the development of pregnancy or diseases of the gestational period (varicose veins, vulvar varicose veins).
Complications
The probability of a complicated course of the disease increases in the presence of nodes larger than 5-7 cm, their localization in the neck, isthmus, lower part of the uterus, multiple myomatosis, placenta placement in the projection of the neoplasm. In 42-58% of cases with fibroids, there is a threat of spontaneous early miscarriage, the risk of premature birth reaches 12-25%. There may be such obstetric complications as fetoplacental insufficiency with delayed fetal development, low placenta location, its premature detachment with normal localization, tight attachment or true increment of placental tissue.
The deformation of the uterine cavity by the tumor contributes to the formation of abnormalities of the fetal bone system and its incorrect presentation. In some pregnant women, submucosal neoplasia prevents the passage of the child through the birth canal. In childbirth, patients with fibroids often experience weakness of labor forces, discoordinated labor activity, possible ruptures of the uterus and its cervix, hypotonic bleeding, postpartum uterine subinvolution. In the presence of fibroids, the frequency of stillbirths doubles. The main non-obstetric complications of myomatosis during pregnancy are necrosis of the node, twisting of its legs. The risk of neoplasia malignancy in the gestational period is minimal.
Diagnostics
The main task of the diagnostic search for fibroids in pregnant women is to assess the factors that can complicate gestation and childbirth — the number and size of nodes, their localization and location in relation to the placenta. Some traditional methods of diagnosing fibroids during pregnancy are used only to a limited extent. During a gynecological examination, it is possible to identify the discrepancy between the size of the uterus and the period of pregnancy, to probe large subserous tumors on its anterior wall. Angiography of the uterus, CT of the pelvic organs and other X-ray examinations are not recommended due to possible damaging effects on the fetus. Hydrosonography and hysteroscopy are strictly prohibited. To clarify the data on fibroids in a pregnant woman , they are usually used:
- Ultrasound of the uterus. Myomatous nodes have the appearance of rounded heterogeneous formations with clear, even contours. With the predominance of low-differentiated smooth muscle cells in the composition, neoplasia is hypoechoic, the presence of a large number of connective tissue fibers is evidenced by hyperechogenicity. The method allows you to clearly determine the size of the tumor, the number of nodes and their location.
- Doppler ultrasound of the uterine vessels. The advantage of Dopplerography is the possibility of studying both the features of the blood supply of myomatous neoplasia and uteroplacental blood flow. Since when the placenta is located in the neoplasm area, the risk of abnormalities of its development increases, the assessment of blood supply ensures timely detection of violations of transplacental dynamics.
MRI of the uterus is performed according to indications in complex diagnostic cases no earlier than 4 months of gestation. Differential diagnosis of fibroids is carried out with adenomyosis, cancer and uterine sarcoma, endometrial polyps, ovarian tumors, retroperitoneal neoplasms, trophoblastic disease. If necessary, a pregnant woman is prescribed consultations with a urologist, oncologist, surgeon.
Treatment of uterine fibroids during pregnancy
The main medical task when accompanying a pregnant woman with a myomatous node is the prolongation of gestation to safe terms for the birth of a child. The scheme of medical therapy of fibroids during pregnancy includes drugs that reduce the tone of the myometrium, improve blood flow in the uterine wall and indirectly in the fetoplacental complex:
- Antispasmodics. Papaverine derivatives with a pronounced myotropic effect and moderate vasodilating effect are recommended. Drugs of this group, by inhibiting phosphodiesterase and intracellular cAMP accumulation, inhibit the flow of calcium ions into myocytes, reducing the tone and contractile activity of smooth muscle fibers.
- β2-sympathomimetics. Selective adrenostimulating drugs have a pronounced tocolytic effect, relax the myometrium well, without affecting the cardiovascular system and without impairing uteroplacental blood flow. Due to the activation of adenylate cyclase and an increase in cAMP levels, intracellular calcium concentration and the contractility of myocytes are reduced.
- Antiplatelet agents. The expediency of prescribing drugs with an antithrombotic effect is due to the need to prevent thrombotic necrosis of fibroids. Due to the enhancement of the antiplatelet properties of prostaglandins and the suppression of phosphodiesterase activity, the drugs prevent platelet aggregation and stimulate moderate peripheral vasodilation.
Surgical treatment (conservative myomectomy) during pregnancy is carried out in exceptional cases with atypical (cervical, isthmus) arrangement of smooth muscle nodes, large and giant single or multiple tumors that interfere with the normal development of the child, nutritional disorders of neoplasms with signs of its destruction.
Planned myomectomy is performed at 16-19 weeks of gestation, when the physiological progesterone protection is maximum. Due to the high risk of termination of pregnancy, removal of fibroids after 22 weeks is not recommended. In case of leg twisting and tumor necrosis, surgical intervention is performed urgently for vital indications. Extremely rarely, when spontaneous termination of pregnancy has begun with massive bleeding and technical impossibility of curettage due to the cervical-isthmian localization of the node, extirpation of the uterus with a fetal egg is performed.
Most pregnant women with fibroids are recommended natural childbirth with a shortening of the period of exile. An indication for a planned caesarean section is multiple myomatosis with large neoplasms, especially when they are placed in the lower segment. Emergency operative delivery is performed according to obstetric indications with a clinically narrow pelvis, therapeutically resistant weakness of labor, oblique or transverse fetal position, loss of umbilical cord loops, threat of rupture of the uterus. In some cases, an extended intervention is performed with a myomectomy or removal of the uterus.
Prognosis and prevention
From 60 to 90% of pregnancies with uterine fibroids proceed without complications. In 49-60% of cases, small nodes practically do not change in size, in 22-32% there is an increase in tumor volume by 12-25%, in 8-27% of pregnant women, the neoplasm decreases by 5-10% in the third trimester. In some patients, fibroids up to 5 cm in size completely resolve in the postpartum period. In the presence of fibroids, a woman who is planning a pregnancy must undergo a course of conservative treatment to reduce the size of the nodes or remove them surgically if there are appropriate indications. To prevent complications, early registration in a women’s clinic, dynamic observation of an obstetrician-gynecologist with scheduled and unplanned ultrasound to assess the condition of the tumor and fetus is recommended.