Increased menstrual bleeding most commonly occurs with submucosal and intramural fibroids, presenting as heavy menstrual flow, prolonged periods, or irregular vaginal bleeding. The main causes of increased bleeding are: enlarged endometrial surface area, endometrial hyperplasia stimulated by estrogen, impaired uterine contraction due to fibroids, and pelvic congestion interfering with blood circulation. Chronic blood loss often results in varying degrees of anemia.
The classic symptoms of uterine fibroids are heavy menstruation and secondary anemia, although many patients have no obvious symptoms. Symptoms are closely related to the location and size of the fibroids.
1. Increased Menstrual Bleeding
This mainly occurs in submucosal and intramural fibroids, with manifestations including heavy menstrual flow, prolonged menstruation, and irregular uterine bleeding. As the endometrial surface area expands, estrogen stimulates hyperplasia; fibroids restrict uterine contraction and cause pelvic congestion. Over time, persistent bleeding leads to secondary anemia.
2. Lower Abdominal Mass
When subserosal or intramural fibroids grow large enough to extend beyond the pelvic cavity, patients can often feel a firm mass themselves, usually accompanied by a dragging or heavy sensation.
3. Pressure Symptoms
Fibroids in the lower uterine body or cervix, especially when incarcerated in the pelvis, can compress pelvic tissues and nerves, causing lower abdominal pain and lumbosacral soreness. Fibroids growing anteriorly or posteriorly may compress the bladder, urethra, or rectum, leading to frequent urination, difficulty urinating, urinary retention, or constipation. Fibroids extending laterally form broad‑ligament fibroids; compression of the ureter may cause hydroureter or hydronephrosis, while compression of pelvic blood vessels and lymphatics can lead to lower‑extremity edema.
4. Pain
Pain is relatively uncommon. Besides nerve compression, pedunculated submucosal fibroids may trigger uterine contractions and cramping pain. If fibroids block the cervical canal and obstruct menstrual flow, dysmenorrhea may occur. Severe acute abdominal pain can result from torsion of a pedunculated subserosal fibroid, red degeneration during pregnancy, or infection.
5. Effects on Pregnancy and Delivery
Subserosal fibroids usually do not affect conception. However, intramural fibroids near the uterine cornua may compress the fallopian tube, and submucosal fibroids may cause endometrial infection or hyperplasia, leading to infertility. If pregnancy occurs, insufficient blood supply or a narrowed uterine cavity may restrict fetal development, causing miscarriage or preterm birth. At term, uterine cavity distortion may lead to malpresentation, and impaired uterine contractions may cause dystocia and postpartum hemorrhage.