What are fibroids?
Uterine leiomyomas (also referred to as fibroids or myomas) are the most common pelvic neoplasm in females. Fibroids are noncancerous monoclonal tumors arising from the smooth muscle cells and fibroblasts of the myometrium. They arise in reproductive-age females and, when symptomatic, typically present with symptoms of abnormal uterine bleeding and/or pelvic pain/pressure. Uterine fibroids may also have reproductive effects (eg, infertility, adverse pregnancy outcomes).
Uterine fibroids are benign, hormone-dependent neoplasms (benign tumors) of the myometrium, which mainly consist of smooth muscle cells and are therefore classified as leiomyomas (from Greek leíos = “smooth” and mys = “muscle”). The leiomyoma is usually a nodular, encapsulated, round tumor. Fibroids can occur individually (solitary fibroids), but they are often distributed in large numbers in the uterus, which are then referred to as myomatosus uterus/fibroid uterus.
Uterine fibroids is a hormone-dependent benign neoplasm that occurs in the muscular wall of the uterus in women of reproductive age.
Fibroids are the most common type of tumor in the female reproductive organs. Uterine fibroids are very common, especially among women aged 30-45.
It is a tangle of chaotically intertwined smooth muscle fibers and is found in the form of a round knot. Such nodes are called myoma nodes.
It is not entirely clear what causes fibroids, but estrogen and progesterone seem to play a role.
Fibroids were first described in 1973 by the British pathologist Matthew Bailey, and at the present time, uterine fibroids are one of the most common gynecological diseases.
Types of Fibroids
in terms of structure, uterine fibroids can be represented by various tissues:
- Leiomyoma – a neoplasm of muscle fibers;
- Fibroma – formed by connective tissue and is quite rare in its pure form;
- Rhabdomyoma is a benign tumor that develops from striated muscle tissue;
- Angiomyoma is a tumor with a well-developed network of blood vessels .
In relation to the muscular layer of the uterus, three types of growth of fibroids are also distinguished:
- Internal or intermuscular fibroids grow in the middle and thick layer of the uterus;
- Subperitoneal or subserous fibroids grow from a thin outer fibrous layer of the uterus, the so-called serous. Such a fibroid can be both on a wide base and on a narrow stalk.
- Submucosal or submucosal fibroids grow from the wall of the uterus towards the inner lining of the uterus – the endometrium. Submucosal uterine fibroids can also be stalk-based or broad-based.
Classification of uterine fibroids by the number of nodes:
- A single fibroid is a myomatous node, which is clearly delimited from the surrounding muscular layer of the uterus by a false capsule formed by compressed muscle tissue. The dimensions of a single node, as a rule, range from a few millimeters to 8-10 cm, rarely more.
- Multiple or multinodular uterine fibroids, consisting of two or more myomatous nodes, in some cases having a bizarre “node-on-node” arrangement.
The size of a fibroid can vary, some grow up to 20 centimeters and in individual cases can grow to simulate a pregnancy in the 5th month.
The fibroids are mainly classified according to their location. There are three types of fibroids classified by their location:
- Intramural Fibroids: the most common are intramural fibroids. These grow in the uterine wall. If they are small, they do not change the shape of the uterus; if they increase in size, they may become ovoid-shaped.
- Subserosal Fibroids: the subserosal fibroids grow towards the serosa (outer margin of the uterus). When they increase in size, they can grow outward to such an extent that they are only connected to the uterus via a stalk and are then referred to as pedunculated
myoma extending outside of the uterus.
- Submucosal Fibroids: Submucosal fibroids grow towards the internal uterine cavity. They are rare (5% of fibroids), but cause symptoms early on. Submucosal fibroids can also appear as pedunculated myomas and thus penetrate into the cervix uteri.
In some clinical settings Uterine fibroids are further described using the International Federation of Gynecology and Obstetrics (FIGO) classification system for fibroid location is the most commonly used classification system and is as follows:
- Intramural myomas (FIGO type 3, 4, 5) – These fibroids are located within the uterine wall. They may enlarge sufficiently to distort the uterine cavity or serosal surface. Some fibroids may be transmural and extend from the serosal to the mucosal surface.
- Submucosal myomas (FIGO type 0, 1, 2) – These leiomyomas derive from myometrial cells just below the endometrium (lining of the uterine cavity). These neoplasms protrude into the uterine cavity. The extent of this protrusion is described by the FIGO/European Society of Hysteroscopy classification system and is clinically relevant for predicting outcomes of hysteroscopic myomectomy
- Type 0 – Completely within the endometrial cavity
- Type 1 – Extend less than 50 percent into the myometrium
- Type 2 – Extend 50 percent or more within the myometrium
- Subserosal myomas (FIGO type 6, 7) – These fibroids originate from the myometrium at the serosal surface of the uterus. They may have a broad or pedunculated base and may be intraligamentary (ie, extending between the folds of the broad ligament).
- Cervical myomas (FIGO type 8) – These leiomyomas are located in the cervix rather than the uterine corpus.
Symptoms of fibroids:
Symptoms of uterine fibroids
Most patients with fibroids do not have symptoms. It is discovered by chance during a gynecological examination or ultrasound.
Common symptoms of uterine fibroids may include:
– Heavy and prolonged menstrual bleeding. The most common symptom is progressive and heavy bleeding during menstruation. It is caused by the growth of fibroids bordering the uterine cavity. The menstrual period may also last longer than usual.
– menstrual pain. Heavy bleeding and cloths can cause severe cramps and pain during your period.
– Pressure and pain in the abdomen and lower back. Large fibroids can cause pressure and pain in the abdomen or lower back, which occurs between periods and resembles menstrual cramps.
– Problems with urination. Large fibroids can press on the bladder and urinary tract, causing frequent urination or an urge to urinate, especially at night when the woman is lying down. Fibroids can also put pressure on the ureters, which in turn can make it difficult or block the flow of urine.
– Constipation. The pressure of the fibroids on the rectum can cause constipation.
– Pain during intercourse.
– Enlargement of the uterus and abdomen. As fibroids grow, some women begin to feel them as hard lumps in their lower abdomen. A very large fibroid may cause the abdomen to enlarge and cause a feeling of heaviness or pressure.
Diagnosing uterine fibroids
– Gynecological examination and patient history. As already mentioned, the gynecologist can detect some fibroids during a gynecological examination.
During a pelvic exam for fibroids, the doctor will check for pregnancy-related indicators and other conditions such as ovarian cysts. You will be asked questions about your family history of fibroids and the length and nature of your menstrual bleeding. Other causes of abnormal uterine bleeding should also be considered.
– Ultrasound. Ultrasound is the standard imaging modality for detecting uterine fibroids. Ultrasound can be either transabdominal or transvaginal. In a transabdominal ultrasound, an ultrasound transducer is moved across the abdomen. In a transvaginal ultrasound, a transducer is inserted into the vagina.
– Hysterosonography. Along with ultrasound, hysterosonography can be performed, using ultrasound along with saline that is infused into the uterus to enhance the visualization of the uterus and gives much more accurate results in detecting pathologies of the uterine cavity, including tubal patency.
– Hysteroscopy. Hysteroscopy is a procedure that can be used to determine if there are fibroids, polyps, or other causes of bleeding. It can also be used during surgery to remove fibroids.
During the procedure, a long, flexible tube called a hysteroscope is used. It is inserted into the vagina through the cervix and reaches the uterus. A fiber optic light source and tiny cameras in the tube allow the doctor to view the cavities in detail. The uterus is also inflated with saline or carbon dioxide to inflate the cavities and make viewing easier.
Hysteroscopy is a non-invasive procedure and does not require incisions, however, some women report severe pain during her behavior, so local, regional, or general anesthesia may be used.
– Laparoscopy. In some cases, laparoscopic surgery may be performed as a diagnostic procedure. Whereas hysteroscopy allows the doctor to view the cavities inside the uterus, laparoscopy provides a view outside the uterus, including the ovaries, fallopian tubes, and a general examination of the pelvic region.
– Biopsy. In some cases, an endometrial biopsy may be needed to determine if there are abnormal cells in the uterine lining that are a precursor to cancer.
– Laboratory tests. You may also need a complete blood count to check for signs of anemia.
– Exclusion of other possible causes that can cause heavy bleeding. Almost all women, at some point in their reproductive lives, experience heavy bleeding during their menstrual period. Therefore, it is very important to rule out other conditions that cause or may cause heavy bleeding.
Treatment for uterine fibroids
The following treatment options are possible:
- Surgical (removal of fibroids).
- Uterine artery embolization (UAE).
- HIFU-ablation of myomatous nodes under the control of MRI.
Currently, there are many different methods of treating uterine fibroids, depending on its shape and size, the age of the patient, reproductive plans and the presence of comorbidities.
Indications for surgical removal of uterine fibroids:
- profuse prolonged menstruation leading to anemia;
- large tumor size (more than 12 weeks);
- violation of the functions of adjacent organs;
- chronic pelvic pain;
- rapid tumor growth (more than 4 weeks during the year);
- tumor growth in postmenopausal women;
- submucosal uterine fibroids;
- subserous node on the leg with the threat of torsion;
- node necrosis;
- atypical arrangement of nodes;
- violation of reproductive function;
- infertility in the absence of other causes.
Types of surgical treatment:
- Hysterectomy – removal of the uterus – a radical method of surgical treatment. Operation access: vaginal, laparoscopic, laparotomic.
- Conservative myomectomy – offered to women of reproductive age. The removal of the myomatous node is carried out with the preservation of the uterus. Accesses: laparoscopy, laparotomy, vaginal, hysteroresectoscopy, combined (laparoscopy and hysteroresectoscopy).
- Hysteroresectoscopy is performed if the size of the uterus is not more than 10 weeks, the diameter of the submucosal nodes is up to 6-7 cm.
- Uterine artery embolization (UAE) is an alternative to surgical treatment.
Indications for embolization: symptomatic uterine fibroids (hemorrhagic syndrome, pain syndrome), preoperative preparation.
Contraindications: subserous and submucosal uterine fibroids on a thin basis, large nodes (the dominant node is more than 7 cm); pelvic inflammatory disease, contrast allergy, borderline or malignant pelvic disease, coagulation disorders, renal dysfunction, heart failure.
Despite the active development of surgical techniques, not all nodes require surgical removal. There is hormone therapy that suppresses the growth of fibroids.
Indications for hormonal treatment: preoperative preparation for myomectomy and hysteroresectoscopy, intramural or subserous arrangement of nodes on a wide base.
Hormone treatment is not carried out: with meno-metrorrhagia and severe pain syndrome. Concomitant extragenital diseases are a contraindication to surgical treatment.
The woman’s age and the severity of her symptoms are important factors in the choice of treatment.
Many women with fibroids choose not to be treated, especially if they are approaching the age of menopause. Fibroids tend to grow slowly and stop growing after menopause.
However, if the tumor is causing pain, bleeding , or is growing rapidly, treatment is indispensable. Treatment for fibroids includes various medications and surgical methods.
In modern clinical practice, there are 3 approaches to treatment:
- Expectant tactics. This approach does not require treatment, especially if the woman is close to reaching menopause or the fibroids are not causing any symptoms. Periodic gynecological exams and ultrasounds can help monitor the condition of fibroids.
– Anti-inflammatory and painkillers. For pain associated with fibroids, women can use acetaminophen (Tylenol) or non-steroidal anti-inflammatory drugs such as ibuprofen or naproxen.
– Hormonal contraceptives. Continuous dosed use of oral contraceptives can normalize and shorten the menstrual period. They are also sometimes used to control heavy menstrual bleeding associated with fibroids, but unfortunately they do not reduce the growth of fibroids. Recently, new types of continuous-dose oral contraceptives have become available that can reduce the number of menstrual periods a woman has in a year. They block or suppress estrogen , progesterone, or both.
– Intrauterine devices. A progestin-releasing intrauterine device may help control excessive menstrual bleeding called menorrhagia. The Mirena intrauterine system containing levonorgestrel-releasing is approved for the treatment of menorrhagia and has shown excellent results. Many doctors now recommend Mirena as the first choice for treating heavy menstrual bleeding, especially for women who may be facing a hysterectomy (removal of the uterus).
– GnRH agonists. Taking gonadotropin-releasing and agonists to reduce estrogen and progesterone, lead to a decrease in the size of fibroids by stopping ovulation. GnRH agonists block the production of reproductive hormones such as luteinizing hormone (LH) and follicle-stimulating hormone (FSH). As a result, the ovaries stop ovulating and no longer produce estrogen. Simply put, GnRH agonists cause temporary menopause.
GnRH agonists may be used as a medical treatment for fibroids in women who are approaching the age of menopause. They can also be used as a preoperative treatment 3 to 4 months prior to surgery to reduce the size of the fibroids in order to eventually perform a minimally invasive surgical procedure.
As a gonadotropin-releasing hormone (GnRH) agonist, subcutaneous capsules , monthly injections of Leuprolide (Lupron), and Sinarel nasal spray are used.
Before using these drugs, the physician must be sure that no other complicating conditions are present, in particular leiomyosarcoma (cancer). The use of these drugs can weaken the treatment of malignant neoplasms and lead to serious complications.
Common side effects that can be very serious in some women include menopause-like symptoms: hot flashes, night sweats, vaginal dryness, weight gain, and depression. The most important concern is possible osteoporosis due to a decrease in estrogen levels. Women should not take these drugs for more than 6 months. It should be remembered that these drugs alone are not able to prevent pregnancy. Also, if a woman becomes pregnant while using them, there is some risk of birth defects.
- surgery. There are many surgical options, ranging from less invasive to very invasive. These include removal of fibroids – myomectomy, removal of the endometrium – endometrium, reduction of the blood supply to the uterus – embolization of the uterine arteries, and removal of the uterus – hysterectomy.
Women should discuss each option with their doctor. Deciding on a specific surgical procedure depends on the location, size, and number of fibroids. Some affect treatments a woman’s fertility and are only recommended for women who are not of childbearing age or who do not plan to become pregnant.
Indications for surgical treatment of uterine fibroids are:
- Rapid growth of fibroids;
- Severe bleeding leading to anemia;
- multiple fibroids;
- large fibroids;
- Severe pain syndrome;
- Torsion of the leg or necrosis of the fibroids;
- The combination of uterine fibroids with an ovarian tumor or endometriosis , or a precancerous condition of the cervix ;
- Infertility due to atypical arrangement of nodes;
- Suspicion of malignant degeneration of fibroids.
Myomectomy is a surgical procedure aimed at the surgical removal of fibroids only. In this case, the uterus is not affected, thanks to which it is possible to preserve the reproductive function of a woman. This surgery can also help regulate abnormal uterine bleeding caused by fibroids. Alas, not all women are candidates for myomectomy. If the fibroids are numerous and large, it can lead to significant blood loss.
To perform a myomectomy, the surgeon may use the standard “open” surgical approach, laparotomy, or the less invasive ones, hysteroscopy and laparoscopy.
Laparotomy with myomectomy. Laparotomy is performed by incision of the abdominal wall and conventional “open” surgery. It is used for subserous fibroids that are very large, numerous, when cancer is suspected, or when laparoscopic techniques are unavailable or contraindicated. Recovery after a standard abdominal myomectomy takes 6 to 8 weeks. Open laparotomy carries a higher risk of scarring and blood loss, and the risk of recurrence of new fibroids is also higher than with less invasive procedures.
Hysteroscopy. Hysteroscopic myomectomy can be used for submucosal or submucosal fibroids located in the uterine cavity. In this procedure, fibroids are removed using an instrument called a hysteroscopic resectoscope, which is inserted into the uterine cavity through the vagina and cervical canal, after which the doctor uses electrosurgical instruments to remove the tumor.
Laparoscopic myomectomy. Women whose uterus is no larger than it would be at 6 weeks pregnant and who have few subserous nodes may have laparoscopic surgery. Laparoscopy requires only tiny incisions, is performed under image guidance, and requires much less recovery time than laparotomy.
Complications of myomectomy are generally the same as for other surgical procedures, including bleeding and infection. This operation is not a 100% result method. Fibroids may reappear after myomectomy.
Embolization of the uterine arteries
Uterine artery embolization (UAE), also called uterine fibroid embolization, is a relatively new treatment for fibroids. The EMA of the fibroid deprives it of its blood supply, causing the fibroid to contract. UAE is a minimally invasive and technically non-surgical therapy. It is much less invasive than hysterectomy and myomectomy and has a shorter recovery time than other procedures. The patient remains conscious, albeit under anesthesia, during the procedure, which takes about 60 – 90 minutes.
This procedure is usually performed in the following order:
The patient is sedated and a local anesthetic is applied to the skin around the groin.
The interventional radiologist makes a small incision in the skin (about 1 cm) and inserts a catheter into the femoral artery, which feeds the fibroids. Parts of a special embolization preparation are introduced through the catheter. These particles block the blood supply to the tiny arteries that feed the fibroids, causing the fibroids to die and be replaced by connective tissue. This leads to a significant reduction or disappearance of myomatous nodes.
Patients usually stay overnight in the hospital after the procedure has been performed and pain medication has been given. Pelvic cramps are common for the first 24 hours after the procedure.
The recovery time after the procedure, until returning to work, is 1 to 2 weeks, but the reduction of fibroids can take from several months to several years.
Most patients experience a brownish vaginal discharge for several days after UAE, which may last until the start of the next menstrual cycle. Regular menstrual cycles resume within 2 to 3 months after the procedure. Heavy menstrual bleeding decreases by the second or third cycle.
Can I Get Pregnant After Uterine Artery Embolization?
In general, UAE is considered to be an option only for women who do not plan to have children. Although in clinical practice there have been cases of pregnancies after this procedure. Some evidence suggests that UAE may increase the risk of miscarriage in women who become pregnant. Some women who have had UAE have gone through menopause after the procedure. And yet, menopause in women who have had UAE is more likely after age 45.
Studies on uterine artery embolization show a high patient satisfaction rate (over 90%) and a low complication rate. Symptoms of menorrhagia as well as pelvic pain improve in 85-95% of patients within 3 months of treatment. Uterine artery embolization is an effective treatment for fibroids in most patients. However, some patients may have recurrent fibroids requiring repeat embolization or hysterectomy.
Ablation of the endometrium
Endometrial ablation destroys the lining of the uterus (endometrium) and is usually done to stop heavy menstrual bleeding. The destruction of the endometrium can be carried out using heat, cold, microwave radiation, or other methods. This procedure is not appropriate for large fibroids or fibroids that have grown outside the lining of the uterus. In some cases, it stops menstruation completely. For some women, menstrual bleeding does not stop, but decreases significantly.
This procedure is usually done on an outpatient basis and can take as little as 10 minutes. Recovery usually takes several days.
Ablation of the endometrium significantly reduces the chance of getting pregnant. However, pregnancy can still occur, although this procedure increases the risk of complications, including miscarriage. Therefore, women who have had this procedure still need to use contraceptive methods.
Magnetic resonance focused ultrasound (HIFU-MRI)
HIFU-MRI is a non-invasive procedure that uses high intensity ultrasound waves to heat and remove uterine fibroids. This is a kind of “thermal ablation”. The procedure is performed using a device, ExAblate, which combines magnetic resonance imaging (MRI) and ultrasound.
During the 3-hour procedure, the patient lies inside the MRI machine. He is given a mild sedative to help him relax but remain conscious throughout the procedure. The radiologist uses MRI to accurately target the fibroid and sends an ultrasound beam to remove tissue from the fibroid. MRI also helps monitor the temperature generated by the ultrasound.
HIFU-MRI is only suitable for women who are on the verge of menopause or who are not planning a pregnancy. It should also be borne in mind that this procedure is not suitable for all types of fibroids. So, HIFU-MRI is not recommended if the distance between the uterine myoma and the skin exceeds 12 cm, if the access of the beam to the neoplasm is limited by scars or intestinal loops, the diameter of the fibroid should not exceed 10 cm, the number of formations should not exceed 6 fibroids. Pregnancy is a complete contraindication.
Hysterectomy is the surgical removal of the uterus. The ovaries may also be removed, although this is not necessary to treat fibroids. Hysterectomy is the only treatment that is 100% successful in getting rid of fibroids and is an option if other treatments have failed or are not possible.
After a hysterectomy, a woman permanently loses the opportunity to become pregnant, but if the ovaries are removed along with the uterus, the hysterectomy causes the immediate onset of menopause.
Types of hysterectomy:
- Abdominal hysterectomy
- Vaginal hysterectomy
- Laparoscopic hysterectomy
- Robotic hysterectomy
Abdominal hysterectomy is best for women with large fibroids when ovaries need to be removed or when cancer is present.
A vaginal hysterectomy only requires a vaginal incision through which the uterus is removed
Robotic hysterectomy is performed using special equipment. This approach is most commonly used when the patient is diagnosed with cancer, is very overweight, and vaginal surgery is not safe.
Complications of uterine fibroids
– Influence on fertility. Most fibroids have only a small effect on a woman’s fertility. Female infertility is usually associated with other factors.
– Influence on pregnancy . Fibroids can increase the risk of pregnancy complications.
They may include:
- C section;
- Incorrect position of the fetus during childbirth, the child enters the birth canal with his feet or buttocks forward;
- premature birth;
- Placenta previa, i.e. a condition when the placenta covers the cervix partially or completely;
- postpartum bleeding;
– Anemia. Anemia or iron deficiency may develop if the fibroid causes excessive bleeding. Surprisingly, small submucosal fibroids are more likely to cause abnormally heavy bleeding than large ones.
In most cases, mild anemia is treated with dietary changes and iron supplements. However, prolonged and severe anemia can cause heart problems.
– Urinary tract infections. Large fibroids can press on the bladder and sometimes lead to urinary tract infections. Pressure on the ureters can lead to obstruction of the urinary tract and kidneys.
– Uterine cancer. Fibroids are almost always benign, even if they contain abnormally shaped cells. Uterine cancer usually develops in the lining of the uterus (endometrial cancer). Only in rare cases (less than 0.1%), cancer develops due to malignant changes in the uterus, the so-called leiomyosarcoma. However, with rapid premenopausal uterine enlargement or even slow postmenopausal fibroid enlargement, a woman needs specialist evaluation to rule out cancer.
Causes and risk factors for the development of uterine fibroids
- Age. Fibroids are most common among women in their 30s and early 50s. After menopause, fibroids tend to shrink. About 20-40% of women aged 35 and older have fibroids that are large enough to cause symptoms.
- Race. Uterine fibroids are especially common in African American women, who tend to develop fibroids at a younger age than white women.
- Family history and heredity. A history of fibroids in a mother or sister may increase the risk.
- Hormonal imbalance. Uterine fibroids are formed due to increased production of female sex hormones – estrogens.
- immunological reasons. Sometimes a violation of the cellular immunity system leads to a decrease in the detection of cells with a disturbed DNA structure by the body.
- hypoxic hypothesis. Insufficient oxygen saturation of the tissues of the uterus causes a violation of the metabolic process and the synthesis of uterine cells.
- Other possible risk factors. Obesity and high blood pressure may be associated with an increased risk of developing fibroids.
Although the exact cause is not yet fully understood, it has been established that both estrogen and progesterone play a key role in the development of fibroids. Some studies suggest that estrogen inhibits the tumor suppressor gene p53 in myoma tissue. This leads to an unchecked proliferation of the cells with an increase in the size of the myoma.
Presumably there is also a genetic predisposition for the development of uterine fibroids. It is believed that there are at least 145 different genes that influence the development of fibroids. Among other things, these genetic factors regulate the effect of hormones in the formation of myoma.
Some associated risk factors include:
- Early menarche – which refers to mensuration/menarche before 12 years of age. This is thought to be the result of increases the number of cell divisions, which increases the risk of mutations in the genes that control myometrium proliferation.
- Reproductive dysfunction (absence of childbirth) . Anovulation – with infertility allows for the continuous effect of estrogens on the myometrium which is unopposed. while pregnancy reduces the time of free exposure of estrogens to the myometrium as these hormonal effects are reduced during pregnancy.
- Obesity, leading to insulin resistance – increases the fraction of free estrogens. At the same time, the conversion of androgens to estrogens increases in adipose tissue – this mechanism is more important in postmenopausal women.
The growth of fibroids is multifactoral and along with hormonal factors which effect fibroid growth a certain role is played by hereditary predisposition. There is also an immune theory for the growth of fibroids: the rapid growth of fibroids is observed with pronounced immune disorders that contribute to increased cell growth, angiogenesis and inflammation. Various growth factors play an important role. Damage to the structure of the uterus: curettage, inflammation, mutations – lead to the expression of growth factors and increase the risk of uterine fibroids and endometrial pathology. Myoma of the uterus can proceed for a long time without pronounced clinical manifestations.
Myoma is one of the most common benign tumors in women. Postmortem, fibroids can be detected in 25% of women over the age of 30. The frequency peak is between the ages of 35 and 45.
The prevalence increases with age up to menopause. Fibroids are also known to be more common in African Americans and do not occur in postmenopausal women. In addition, fibroids are more common in nulliparous women (women who have never given birth) than in women with children.
In the Nurses’ Health Study II, a large prospective study in the United States, over 95,000 females ages 25 to 44 were followed from 1989 to 1993. The age-standardized incidence rates of fibroids confirmed by ultrasound or hysterectomy were 9.2 per 1000 woman-years overall, 30.6 for Black females, and 8.9 for White females. Overall incidences by age group were: 25 to 29 (3.3 per 1000 woman-years), 30 to 34 (6.8), 35 to 39 (10.3), and 40 to 44 (16.0).
- In a population-based study of an urban health plan in Washington, DC, 1364 females ages 35 to 49 years were randomly selected and assessed by survey and/or ultrasound. Newly detected fibroids were present in 59 percent of Black females and 43 percent of White females; for females in their late 40s, the estimated frequency of fibroids was >80 percent and near 70 percent for Black and White females, respectively.
- A cross-sectional study in Europe of 1756 patients with fibroid-related symptoms found myomas in 12 to 24 percent. Myomas are clinically apparent in approximately 12 to 25 percent of reproductive-age females and noted on pathologic examination in approximately 80 percent of surgically excised uteri.
- A detailed pathologic study of 100 hysterectomy specimens found myomas in 77 percent of uterine specimens. Most patients had multiple myomas, with an average of 7.6 fibroids.
- An ultrasound screening study of asymptomatic females aged 18 to 30 found a prevalence of 26 percent in Black females and 7 percent in White females.
The prevalence of leiomyomas increases with age during the reproductive years . Leiomyomas have not been described in prepubertal girls, but they are occasionally noted in adolescents. Most, but not all, patients have shrinkage of leiomyomas after menopause.