Secondary Amenorrhea Definition
Secondary amenorrhea is defined as the absence of menstrual cycles for 6 months or longer in women who previously had regular menstruation, or 3 months in women who previously had regular cycles. 1, 2
Standard Definitions Across Guidelines
The medical literature presents two slightly different thresholds depending on prior menstrual regularity:
- For women with previously regular cycles: Absence of menses for 3 months constitutes secondary amenorrhea 2, 3
- For women with previously irregular cycles: Absence of menses for 6 months is required for diagnosis 1, 2, 4, 5, 3
The 6-month threshold is the most commonly cited standard definition across major guidelines and represents the conservative diagnostic criterion. 1, 2, 4
Special Context: Cancer Survivors
In the specific population of female cancer survivors, a more stringent definition applies:
- Amenorrhea is defined as absence of menstrual cycles for ≥4 months when evaluating for premature ovarian insufficiency (POI), combined with two elevated FSH levels in the menopausal range 6
This 4-month threshold in cancer survivors reflects the need for earlier detection of treatment-related ovarian damage. 6
Clinical Pitfall to Avoid
Do not wait the full 6 months to begin evaluation if red flag symptoms are present. Earlier investigation is warranted when patients present with: 1
- Galactorrhea (suggesting hyperprolactinemia) 6, 1
- Headaches or visual changes (suggesting pituitary pathology) 1
- Signs of eating disorder or significant weight loss 1
- Symptoms of hyperandrogenism or thyroid dysfunction 6
Contraceptive-Induced Amenorrhea Exception
Amenorrhea occurring in the context of hormonal contraceptive use (particularly DMPA injections or implants) does not require medical treatment and is generally not harmful, even when prolonged beyond 6 months. 6 This represents a distinct physiologic state and should not be conflated with pathologic amenorrhea requiring evaluation.