Can Uterine Fibroids and Ovarian Cysts Cause Heavy Bleeding and Irregular Periods?
Yes, uterine fibroids are a well-established cause of heavy menstrual bleeding and can contribute to irregular periods, while ovarian cysts typically do not directly cause heavy bleeding but may cause irregular cycles through hormonal disruption. 1, 2
Uterine Fibroids and Heavy Bleeding
Uterine fibroids (leiomyomata) affect approximately 75% of women of reproductive age, with about 30% experiencing heavy menstrual bleeding (menorrhagia) as a primary symptom. 3 The mechanism is multifactorial:
Fibroids cause prolonged uterine bleeding that can lead to anemia, pelvic pain, bulk symptoms, and reproductive dysfunction. 4 This is particularly true for submucosal fibroids (those protruding into the uterine cavity), which are most likely to cause heavy bleeding. 5
The bleeding occurs through several mechanisms: aberrant vascular architecture around fibroids, formation of irregular blood vessel networks, venous congestion from blocked normal blood flow, and increased local vasoactive growth factors. 3
Fibroids are classified as a structural cause (the "L" in PALM-COEIN) of abnormal uterine bleeding. 1, 2
Fibroids and Irregular Periods
While fibroids primarily cause heavy bleeding rather than irregular timing, they can contribute to cycle irregularity:
Large or multiple fibroids can disrupt normal endometrial function globally, affecting menstrual patterns. 6
The location, size, and number of fibroids determine symptom severity, with submucosal fibroids having the greatest impact on bleeding patterns. 4, 5
Ovarian Cysts and Bleeding Patterns
Ovarian cysts are not directly mentioned in the guidelines as a cause of heavy menstrual bleeding. However, functional ovarian cysts can cause:
Irregular periods through ovulatory dysfunction (the "O" in PALM-COEIN classification), which is a non-structural cause of abnormal bleeding. 1, 2
Ovulatory dysfunction is particularly common in perimenopausal women and can present with irregular, unpredictable bleeding patterns rather than consistently heavy bleeding. 5
Diagnostic Approach
When evaluating heavy bleeding and irregular periods:
Start with combined transabdominal and transvaginal ultrasound with Doppler to identify fibroids, assess endometrial thickness, and evaluate the ovaries. 2, 5
Perform pregnancy testing in all reproductive-age women first. 2
Check thyroid-stimulating hormone and prolactin levels to identify endocrine causes of ovulatory dysfunction. 2, 5
If ultrasound is inconclusive, proceed to MRI of the pelvis, which is superior for visualizing both fibroids and adenomyosis (which frequently coexists with fibroids). 5
Consider endometrial biopsy in perimenopausal women or those with risk factors for endometrial cancer (obesity, diabetes, family history), even with normal imaging. 5
Common Pitfall to Avoid
Do not assume all heavy bleeding in women with known fibroids is due to the fibroids alone. Adenomyosis frequently coexists with fibroids and presents with heavy menstrual bleeding, dysmenorrhea, and dyspareunia, commonly affecting women in their 40s. 1, 2 Missing coexisting adenomyosis can lead to treatment failure, as patients with significant adenomyosis are less likely to experience symptom relief from fibroid-directed therapies alone. 4