Medical Terminology for Twice-Monthly Menstruation
The medical term for having a period twice a month is "polymenorrhea," which describes menstrual cycles occurring at intervals of less than 21 days. 1
Understanding the Terminology
Polymenorrhea specifically refers to abnormally frequent menstrual bleeding with regular cycles that occur more frequently than the normal 21-35 day interval. 1 When a woman experiences two periods within a single calendar month, this typically indicates cycles shorter than 21 days.
Related Terms to Distinguish
It's important to differentiate polymenorrhea from other bleeding patterns:
- Menorrhagia describes heavy cyclical menstrual bleeding (≥80 mL blood loss per cycle) but maintains normal timing 2
- Metrorrhagia refers to irregular, acyclic bleeding occurring between normal menstrual periods 3
- Menometrorrhagia combines both excessive bleeding AND irregular timing—occurring at irregular and/or frequent intervals 4
Clinical Significance
When evaluating twice-monthly bleeding, the underlying cause determines appropriate terminology and management:
- If cycles are regular but frequent (e.g., every 18 days), this is true polymenorrhea and suggests ovulatory dysfunction 1
- If bleeding is irregular and unpredictable, this represents metrorrhagia or menometrorrhagia rather than simple polymenorrhea 3
Common Underlying Causes
Frequent menstrual bleeding patterns warrant evaluation for:
- Anovulatory bleeding from polycystic ovary syndrome (PCOS), thyroid dysfunction, or hyperprolactinemia 5, 1
- Structural abnormalities including endometrial polyps, submucosal fibroids, or adenomyosis 6, 1
- Coagulation disorders, particularly von Willebrand disease, which affects 10-20% of women with objectively documented abnormal bleeding 7
Diagnostic Approach
For women presenting with twice-monthly bleeding:
- Rule out pregnancy with beta-hCG testing first 6
- Screen for sexually transmitted infections that can cause irregular bleeding 6
- Evaluate thyroid function (TSH) and prolactin levels, as these commonly cause ovulatory dysfunction 6
- Assess for structural abnormalities using transvaginal ultrasonography or saline infusion sonohysterography 6, 1
Critical Pitfall to Avoid
Never assume functional bleeding without excluding structural pathology, especially in women ≥35 years where polyps and fibroids become more common. 6 Up to 50% of women with menorrhagia have identifiable organic pathology at hysterectomy, making thorough evaluation essential. 2