Uterine Fibroids


General Considerations

  • Uterine fibroids are leiomyomas, benign tumors of smooth muscle origin
  • Occur in between 20-50% of women > 30 years of age
  • Fibroids may enlarge with elevated estrogen levels
    • They enlarge during the first trimester of pregnancy
  • Uterine fibroids diminish in size after menopause
  • More common in blacks than whites (3:1)
  • Most are intramural, i.e. middle of myometrium
  • Most fibroids are in the fundus and body of the uterus
    • Others can be subserosal or exophytic, or
    • Submucosal and subendometrial (rarely) 

Clinical Findings

  • Most women are asymptomatic
  • Symptoms can include
    • Menorrhagia (increased duration or flow)
      • Frequently from a submucosal fibroid
    • Pain
    • Urinary frequency, urgency or incontinence
    • Infertility 

Imaging Findings

  • Ultrasound is the study of choice
  • Conventional radiography
    • Soft tissue mass arising from the pelvis but separate from the urinary bladder
    • Amorphous, flocculent calcifications in the pelvis
    • Displacement of bowel gas up and out of the pelvis
  • Ultrasound
    • Echogenic mass if fibrosis prevails
    • Hypoechoic, solid mass if muscle component is prevalent
    • Sharp discrete shadows
    • Anechoic features if central portion of fibroid has degenerated
  • MRI
    • Low/intermediate signal intensity of T1 and T2 weighted images
    • High central signal intensity on T2 from hemorrhage
    • May have hyperintense rim
    • With contrast, most are hypointense, about 25% isointense and 10% hyperintense to myometrium
  • CT
    • Mass containing mixed densities, low attenuation if necrotic and higher attenuation if calcified or hemorrhagic 

Differential Diagnosis

  • Ovarian neoplasm or cyst
  • Dilated urinary bladder
  • Intrauterine pregnancy
  • Hydatidiform mole 

Treatment

  • Surgery or arterial embolization for pain and menorrhagia 

Complications

  • Rarely (< 1%), malignant degeneration to a leiomyosarcoma
  • Exophytic fibroid can torse and cause pain
  • Infertility from interference with implantation
  • During pregnancy
    • Spontaneous abortion
    • Intrauterine growth retardation
    • Postpartum hemorrhage

 

Uterine Fibroids. Conventional radiograph on the left show displacement of the bowel gas out of the pelvis because of a large soft tissue mass (white arrows) arising from the pelvis and extending into the lower abdomen. Contrast-enhanced coronal reformatted CT scan of the abdomen on right demonstrates a large pelvic mass comprised of degenerating fibroids (black arrow), hemorrhage (white arrow) and calcification (dotted white arrow).
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Fraser and Pare