How uterine fibroids form

The uterus is a very important reproductive organ for women, but it is also very prone to disease. A typical example is uterine fibroids. Uterine fibroids are the most common benign tumors, which can cause symptoms such as increased vaginal discharge, anemia, uterine bleeding, and in severe cases can cause female infertility. Understanding its causes will help us better prevent and respond. So, how do uterine fibroids form? Let’s take a look below.

The cause of uterine fibroids is still not very clear, and may involve a more complex interaction between normal muscle layer cell mutations, sex hormones and local growth factors.

A large number of clinical observations and experimental results indicate that uterine fibroids are a hormone-dependent tumor. Estrogen is the main factor that promotes the growth of fibroids. Some scholars also believe that growth hormone (GH) is also related to the growth of fibroids. GH can cooperate with estrogen to promote mitosis and promote the growth of fibroids. It is speculated that human placental lactogen (HPL) can also cooperate with estrogen to promote mitosis. It is believed that the accelerated growth of uterine fibroids during pregnancy is related to the high hormone environment during pregnancy, and HPL may also play a role.

In addition, ovarian function and hormone metabolism are controlled and regulated by higher nerve centers, so the activity of nerve centers may also play an important role in the occurrence of fibroids. Uterine fibroids are more common in women of childbearing age, widows, and those with disharmonious sexual lives. Chronic pelvic congestion caused by long-term sexual dysfunction may also be one of the causes of uterine fibroids.

In short, the occurrence and development of uterine fibroids may be the result of the combined action of multiple factors.

Clinical manifestations

1. Symptoms

Most patients are asymptomatic and the disease is only discovered occasionally during pelvic examination or ultrasound. If there are symptoms, they are closely related to the location, speed, degeneration and complications of the tumor growth, but have relatively little to do with the size and number of the tumor. People with multiple subserosal fibroids may not have symptoms, but a small submucosal fibroid can often cause irregular vaginal bleeding or menorrhagia. Common clinical symptoms include:

(1) Uterine bleeding is the most common symptom of uterine fibroids, occurring in more than half of patients. Among them, cyclical bleeding is the most common, which can manifest as increased menstrual volume, prolonged menstrual period or shortened cycle. It may also present as irregular vaginal bleeding that is not related to the menstrual cycle. Uterine bleeding is more common with submucosal fibroids and intramural fibroids, while subserosal fibroids rarely cause uterine bleeding.

(2) Abdominal masses and compression symptoms When the fibroids gradually grow and cause the uterus to enlarge to more than the size of a 3-month pregnant uterus or become a large subserosal fibroid located at the fundus of the uterus, a mass can often be felt in the abdomen, which is more obvious in the early morning when the bladder is full. The mass was solid, movable, and non-tender. When the fibroids grow to a certain size, they can cause compression symptoms of surrounding organs. Fibroids on the anterior wall of the uterus close to the bladder can cause frequent urination and urgency; giant cervical fibroids compressing the bladder can cause difficulty in urination or even urinary retention; fibroids on the posterior wall of the uterus, especially those in the isthmus or posterior lip of the cervix, can compress the rectum, causing difficulty in defecation and discomfort after defecation; giant broad ligament fibroids can compress the ureter and even cause hydronephrosis.

(3) Pain: Uterine fibroids generally do not cause pain, but many patients may complain of a feeling of heaviness in the lower abdomen and pain in the waist and back. When the pedicle of subserosal fibroids is twisted or uterine fibroids undergo red degeneration, acute abdominal pain may occur. It is not uncommon for fibroids to be combined with endometriosis or adenomyosis, which may cause dysmenorrhea.

(4) Increased vaginal discharge. Enlargement of the uterine cavity, increase in endometrial glands, and pelvic congestion can cause increased vaginal discharge. When submucosal fibroids of the uterus or cervix ulcerate, become infected, or necrotic, bloody or purulent leucorrhea will be produced.

(5) Infertility and miscarriage Some patients with uterine fibroids are infertile or prone to miscarriage. The impact on conception and pregnancy outcomes may be related to the growth location, size and number of the fibroids. Giant uterine fibroids can cause deformation of the uterine cavity, hindering the implantation of the gestational sac and the growth and development of the embryo; fibroids compressing the fallopian tubes can lead to obstruction of the lumen; submucosal fibroids can hinder the implantation of the gestational sac or affect the entry of sperm into the uterine cavity. The spontaneous abortion rate in patients with fibroids is higher than that in the normal population, with a ratio of about 4:1.

(6) Anemia: Long-term menorrhagia or irregular vaginal bleeding can cause hemorrhagic anemia. More severe anemia is more common in patients with submucosal fibroids.

(7) A very small number of patients with uterine fibroids may develop polycythemia and hypoglycemia, which are generally believed to be related to the production of ectopic hormones by the tumor.

2. Physical signs

(1) Abdominal examination: If the uterus is enlarged to more than the size of a 3-month pregnancy or has a large subserosal fibroid on the fundus of the uterus, a solid mass may be felt above the pubic symphysis or in the middle of the lower abdomen. The mass is non-tender and solid. If there are multiple uterine fibroids, the shape of the mass will be irregular.

(2) Pelvic examination During bimanual and trimanual gynecological examinations, the uterus is enlarged to varying degrees and is irregular. There are irregular protrusions on the surface of the uterus, which is solid. If there is any degeneration, the texture is soft. The signs of uterine fibroids during gynecological examination vary according to their different types. If the pedicle of a pedunculated subserosal fibroid is long, a solid mass can be felt beside the uterus and it moves freely. This situation can easily be confused with an ovarian tumor. The submucosal fibroids descend to the cervical canal opening, and the cervical opening is loose. The examiner can touch the smooth spherical tumor by inserting his finger into the cervical opening. If it has prolapsed outside the cervical opening, the tumor can be seen. The surface is dark red, and sometimes there are ulcers and necrosis. Larger cervical fibroids can cause the cervix to shift and deform, and the cervix may be flattened or moved up behind the pubic symphysis.