Uterine leiomyomas (also known as fibroids) are benign, hormone-sensitive uterine neoplasms. They are classified as either submucosal (beneath the endometrium), intramural (within the muscular uterine wall of the uterus), or subserosal (beneath the peritoneum) and can occur within the uterine corpus or the cervix. Symptoms depend on the location, size, and number of leiomyomas, and include menstrual abnormalities (e.g., menorrhagia), mass effect (e.g., back, abdominal, and/or pelvic pain; bladder and/or bowel dysfunction), and infertility. Ultrasound is typically used to establish the diagnosis. Treatment is selected using shared decision-making, taking into consideration the patient's desire for fertility and/or uterine preservation, menopausal status, and symptom severity. Asymptomatic patients can often be managed expectantly. Treatment for symptomatic patients may include surgery (myomectomy or hysterectomy), nonsurgical interventional treatments (e.g., uterine artery embolization), and/or pharmacotherapy, including gonadotropin-releasing hormone (GnRH) agonists, GnRH antagonists, intrauterine devices (IUDs), and/or oral contraceptives.
- A benign, hormone-sensitive smooth muscle tumor of the uterus
- Can be submucosal, intramural, or subserosal
- Arises from a single myometrial cell (monoclonal growth) and causes:
- Results in an overgrowth of smooth muscle cells and connective tissue (often multiple tumors)
- The myometrium also develops vascular changes (e.g., increased arterioles and venules, dilated veins).
- The most common tumor of the female genital tract.
Predisposing factors 
- Early menarche (< 10 years of age)
- Age: 25–45 years
- Increased incidence in African American individuals
- Family history
Leiomyomas are classified according to their location. 
- Subserosal leiomyoma: located in the outer uterine wall beneath the peritoneal surface
- Intramural leiomyoma (most common): growing from within the myometrium wall
- Submucosal leiomyoma: located directly below the endometrial layer (uterine mucosa)
- Cervical leiomyoma: located in the cervix
- Diffuse uterine leiomyomatosis: The uterus is grossly enlarged due to the presence of numerous fibroids.
Symptoms depend on the number, size, and location of leiomyomas. Most women have small, asymptomatic fibroids.
- Abnormal menstruation: (possibly associated with anemia): hypermenorrhea, heavy menstrual bleeding; , metrorrhagia, dysmenorrhea
- Features of mass effect
- Reproductive abnormalities
General principles 
- Obtain a detailed history and perform a thorough abdominal and pelvic examination.
- Perform a pelvic ultrasound to confirm the diagnosis.
- Order laboratory studies to screen for complications (e.g., anemia) and rule out other causes of abnormal uterine bleeding.
- Additional studies may be required:
- To further characterize leiomyomas prior to interventional procedures or surgery
- If there is diagnostic uncertainty
Uterine leiomyomas are extremely common (affecting 70% of women) and are often found incidentally on ultrasound; do not attribute abnormal uterine bleeding to leiomyomas until other etiologies have been ruled out! 
Ultrasound pelvis (transvaginal, transabdominal)
- Most appropriate initial test for all patients with a suspected uterine leiomyoma 
- Supportive findings 
Neither plain radiography nor CT is recommended in the workup of leiomyomas because of poor visualization (unless calcified). 
Further imaging 
- : to further evaluate endometrial abnormalities detected on ultrasound
- MRI pelvis without and with IV contrast
Although imaging cannot definitively distinguish between a leiomyoma and a leiomyosarcoma, hypervascularity within a solitary heterogeneous uterine mass should raise suspicion for a leiomyosarcoma. 
Laboratory studies 
- Routine initial studies
- Studies to evaluate abnormal uterine bleeding 
Not routinely performed; consider in case of diagnostic uncertainty
- Hysteroscopy: to evaluate endometrial abnormalities 
- Endometrial biopsy: to assess for alternative etiologies of abnormal uterine bleeding (e.g., polyps, hyperplasia, endometrial carcinoma) 
- Grayish-white surface
- Homogeneous; tissue bundles on cross-section partly in a whorled pattern
- Some leiomyomas may involve regressive changes: scar formation, calcification, and cysts
- Microscopic: Smooth muscle tissue in a whorled pattern with well-demarcated borders, consisting of monoclonal cells interspersed with connective tissue
- Asymptomatic or mild symptoms: expectant management
- Symptomatic leiomyoma
Racial disparity exists in the treatment of leiomyomas: Typically, Black patients are less likely to be offered nonsurgical or minimally invasive therapies than White patients, even after adjusting for clinical features such as leiomyoma size. 
- Asymptomatic or minimally symptomatic patients
- Perimenopausal patients
- Monitor reported symptoms for any worsening at annual well-woman exams.
- Typically, no active treatment is required.
- Surveillance imaging is not routinely required. 
- Recommend follow-up if symptoms change or pregnancy is planned.
- Medications can either be used long-term for symptom control or temporarily as a bridge until a more definitive modality can be performed.
- Pharmacotherapy should be selected based on the patient's symptoms.
- There is currently insufficient evidence to recommend one agent over other for first-line therapy.
|Pharmacotherapy for uterine leiomyoma |
|Predominant symptoms||Agents||Important considerations|
|Heavy menstrual bleeding without features of mass effect|
| || |
|Mass effect with or without heavy menstrual bleeding|| |
Selective progesterone receptor modulators (e.g., ulipristal acetate) and androgenic agonists (e.g., danazol) are used in some countries for the management of leiomyomas; these medication classes are not FDA-approved for managing leiomyomas in the US, as the potential adverse effects are thought to outweigh the benefits.
Nonsurgical interventional treatments 
Uterine artery embolization (UAE)
- A minimally invasive percutaneous radiologic procedure in which an embolic agent (e.g., polyvinyl alcohol) is injected into the uterine arteries that supply the leiomyoma, causing it to shrink
- Significantly reduces leiomyoma size and bleeding
- Complications 
- Postembolization syndrome
- Thromboembolic events (e.g., pulmonary embolism, uterine ischemia and necrosis)
- Bleeding/blood-tinged vaginal discharge; : typically self-limited
- Treatment failure
- Unknown effects on fertility : Counsel patients who wish to conceive about the possible effects of UAE on fertility.
Radiofrequency ablation (RFA) 
- Ultrasound-guided targeted coagulative necrosis of leiomyoma
- A significant decrease in leiomyoma size and symptoms have been noted in studies.
- Low risk of further surgical intervention
- Unknown effects on fertility
Additional modalities (not currently recommended)
- MRI-guided focused ultrasound: a noninvasive procedure that uses high-intensity ultrasound waves; results in coagulative necrosis of the leiomyoma 
- Endometrial ablation: may be beneficial in patients with abnormal uterine bleeding due to leiomyomas
A uterus-preserving surgical option for the removal of leiomyomas
- Recurrence rate: ∼ 25% within 40 months 
- Approach : vaginal, abdominal, or laparoscopic
- Uterine fibroids, adenomyosis, and endometriosis may be present simultaneously in the same patient.
- See also , , and
|Differential diagnosis of uterine leiomyoma|
|Factors||Uterine leiomyoma (fibroids)||Uterine polyps||Uterine leiomyosarcoma |
|Risk factors|| |
|Uterine findings|| || || || || |
|Pathology|| || |
The differential diagnoses listed here are not exhaustive.
Special patient groups
Uterine leiomyomas during pregnancy 
- Estimates of leiomyoma occurrence during pregnancy range from 2.7% to > 25%. 
- The majority of patients with leiomyomas have good outcomes, but increased surveillance by a maternal-fetal medicine specialist is recommended because of the elevated risk of pregnancy complications.
- Select appropriate agents to manage pain caused by uterine leiomyomas; see “Analgesics in pregnancy.”
|Effects of leiomyomas in pregnancy |
|Antenatal period|| |
After pregnancy, leiomyomas typically return to their prepartum size; however, some leiomyomas may spontaneously resolve.