What causes endometrial polyps?

Causes of Endometrial Polyps

Endometrial polyps are primarily caused by excessive estrogen exposure, with key risk factors including obesity, diabetes mellitus, hypertension, and tamoxifen use. 1

Hormonal Factors

Endometrial polyps develop through similar pathways as endometrial cancer, particularly related to estrogen exposure:

• Excess estrogen exposure is the primary cause, which can be:

  • Endogenous sources:

    • Obesity (strongest association with RR 2.21) 1
    • Early menarche/late menopause 1
    • Nulliparity and infertility 1
    • Polycystic ovarian syndrome (PCOS) 1
    • Estrogen-producing tumors 1

  • Exogenous sources:

    • Unopposed estrogen therapy (10-30 fold increased risk) 1
    • Tamoxifen use (particularly in postmenopausal women) 1

Metabolic Factors

Metabolic syndrome components significantly contribute to polyp formation:

• Obesity - strongest metabolic risk factor 1, 2
• Hypertension (RR 1.81) 1, 2
• Diabetes mellitus (particularly Type 2) 1, 2
• Hypertriglyceridemia (RR 1.17) 1

Age-Related Factors

• Postmenopausal status significantly increases risk 2, 3
• Age over 55 is a significant risk factor 1

Genetic Factors

• Lynch syndrome/HNPCC (hereditary non-polyposis colorectal cancer) mutations in DNA mismatch repair genes (MLH1, MSH2, MSH6, PMS2) 1
• Cowden syndrome (variations in PTEN, SDHB, SDHD, and KLLN genes) 1

Natural History

• Approximately 25% of endometrial polyps resolve spontaneously if managed conservatively 2
• The overall risk of malignancy within polyps is approximately 3% 2
• Malignancy risk is higher in:
  • Postmenopausal women (4.93% vs 1.12% in premenopausal) 4
  • Women with abnormal uterine bleeding (5.14% vs 1.89% in asymptomatic) 4

Clinical Implications

• Endometrial polyps are common with a prevalence of about 40% 2
• Most polyps are asymptomatic and discovered incidentally 2
• Symptomatic polyps typically present with abnormal uterine bleeding or subfertility 2, 5
• Polyps may adversely impact endometrial receptivity, potentially contributing to infertility 5

Diagnostic Approach

• Transvaginal ultrasonography is the primary diagnostic tool 2, 6
• Hysteroscopy is the gold standard for diagnosis and allows for treatment 2, 6

Understanding these causative factors is essential for risk stratification and management decisions, particularly when determining which patients require intervention versus observation.