Uterine Fibroids & Adenomyosis

Leiomyomas: biology and risk factors

What they are. Uterine leiomyomas (fibroids) are benign, monoclonal smooth-muscle tumors of the myometrium and the most common pelvic tumor in women; roughly 70–80% of women have them by age 50, though many never cause symptoms. Grossly they are firm, well-circumscribed, rubbery masses with a whorled cut surface; many carry somatic MED12 mutations. Growth depends on estrogen and progesterone, so fibroids tend to enlarge in the reproductive years and in pregnancy and to shrink after menopause.

Risk factors. Black race (earlier onset, larger and more numerous tumors, more symptoms), nulliparity, early menarche, obesity, and a family history. Parity is protective.

Germline fumarate hydratase mutations cause hereditary leiomyomatosis and renal cell cancer (HLRCC): multiple uterine and cutaneous leiomyomas at a young age plus an aggressive renal cell carcinoma.

Presentation and diagnosis

Location drives symptoms. Fibroids are described by their relation to the uterine wall, and each position has a signature.

Exam. An enlarged, irregular ("lumpy"), firm, nontender, mobile uterus.

Imaging. Transvaginal (pelvic) ultrasound is the first test and shows well-circumscribed hypoechoic masses. When bleeding or infertility raises concern for a cavity lesion, saline infusion sonohysterography or diagnostic hysteroscopy shows how far a fibroid projects into the cavity. MRI maps size, number, and position before myomectomy or embolization and helps separate fibroids from adenomyosis.

Labs and sampling. CBC for anemia and a pregnancy test. Abnormal bleeding at age ≥45 (or younger with unopposed estrogen exposure or failed therapy) still needs endometrial sampling—fibroids do not exclude hyperplasia or cancer.

Management

Observation. Asymptomatic fibroids need no treatment regardless of size; the old rule of hysterectomy for a "12-week-size" uterus is obsolete. Follow with exam or ultrasound and expect regression after menopause. Treatment targets bleeding, bulk symptoms, or reproductive problems.

Procedures. The patient's reproductive plans choose the operation.

• Hysteroscopic myomectomy for submucosal fibroids causing bleeding, infertility, or recurrent miscarriage—transcervical, outpatient, and it improves pregnancy rates.
• Myomectomy (laparoscopic, robotic, or abdominal) when fertility is desired; fibroids can recur. After a myomectomy that entered the cavity or cut deeply into the myometrium, plan cesarean delivery because of uterine rupture risk, and avoid misoprostol for term ripening.
• Uterine artery embolization for women done with childbearing who want to avoid surgery: particles occlude the uterine arteries and infarct the fibroids. Expect post-embolization syndrome (pain, fever, nausea); ovarian failure is possible, especially near menopause. Avoid with pregnancy, active pelvic infection, or suspected malignancy.
• Hysterectomy is the only definitive cure and fibroids are its leading indication in the US.

Avoid uncontained power morcellation: an unsuspected leiomyosarcoma can be spread throughout the abdomen.

Pregnancy, degeneration, and malignancy concerns

Red (carneous) degeneration. A fibroid that grows quickly in pregnancy can outstrip its blood supply and undergo hemorrhagic infarction, usually in the second trimester. The patient has acute focal pain and tenderness over the fibroid, low-grade fever, and mild leukocytosis. Care is supportive—analgesia and rest—and it resolves over days to weeks; myomectomy is avoided in pregnancy. Other degenerations: hyaline (most common overall), cystic, and calcific (postmenopausal, "popcorn" calcification).

Other pregnancy effects. Fibroids can cause malpresentation, preterm labor, obstructed labor (low-lying or cervical fibroids), cesarean delivery, and postpartum hemorrhage.

Leiomyosarcoma. Because fibroids should regress after menopause, a new or enlarging uterine mass in a postmenopausal woman—especially with bleeding—raises concern for leiomyosarcoma. It arises de novo rather than from a fibroid and shows coagulative necrosis, marked atypia, and a high mitotic rate. MRI can raise suspicion, but diagnosis is surgical: total hysterectomy removed intact. Rapid growth in a premenopausal woman is rarely sarcoma.

Adenomyosis

Definition. Endometrial glands and stroma lying within the myometrium, producing diffuse, symmetric uterine enlargement. The classic patient is a parous woman in her 40s; prior cesarean or other uterine surgery adds risk. It often coexists with fibroids and endometriosis, and a third of cases are asymptomatic.

Presentation. Heavy menstrual bleeding, progressively worsening secondary dysmenorrhea, chronic pelvic pain, and dyspareunia. The uterus is globular, symmetrically enlarged (usually <14-week size), soft ("boggy"), and tender.

Diagnosis. Transvaginal ultrasound shows heterogeneous myometrium, myometrial cysts, asymmetric wall thickening, and a blurred endometrial–myometrial border. MRI is the best noninvasive test (junctional zone ≥12 mm); definitive diagnosis is histologic, usually on the hysterectomy specimen.

Treatment. NSAIDs plus hormonal suppression—LNG-IUD (the most effective medical option), combined contraceptives, progestins, or GnRH analogs. Hysterectomy is the only definitive treatment; symptoms fade after menopause. Endometrial ablation often fails because the glands sit deep in the myometrium.