What is the medical term for missed menses?

Medical Term for Missed Menses

The medical term for missed menses is amenorrhea, which is defined as the absence of menstruation. Amenorrhea is further classified as primary or secondary based on when it occurs in relation to menarche (the first menstrual period).

Types of Amenorrhea

• Primary amenorrhea: Defined as the absence of menarche by age 15 years, or by age 13 years in the absence of secondary sexual characteristics 1
• Secondary amenorrhea: Defined as the cessation of previously established menstruation for longer than 6 months 1, 2
  • Some guidelines use a shorter timeframe of 3 months for regular cycles 2

Diagnostic Criteria

When evaluating missed menses, healthcare providers should consider:

• Pregnancy status, which should be ruled out first in all cases of missed menses 3
• Duration of absence of menstruation (≥4 months is considered amenorrhea according to some definitions) 3
• Previous menstrual history 3
• Hormone levels, particularly follicle-stimulating hormone (FSH) 3

Common Causes of Amenorrhea

Physiological Causes

• Pregnancy (most common cause in reproductive-age women) 1, 4
• Lactation 4
• Menopause (natural cessation of menses after age 40) 3

Pathological Causes

• Hypothalamic causes:

  • Functional hypothalamic amenorrhea (accounts for 20-35% of secondary amenorrhea cases) 1
  • Stress-induced disruption of luteinizing hormone pulsatility 5
  • Low energy availability/nutritional deficiencies 5

• Pituitary causes:

  • Hyperprolactinemia (accounts for approximately 20% of secondary amenorrhea cases) 1
  • Pituitary adenomas 4

• Ovarian causes:

  • Polycystic ovary syndrome (PCOS) - one of the most common causes 5, 1
  • Primary ovarian insufficiency (POI) 1, 2

• Other endocrine causes:

  • Thyroid dysfunction 1
  • Hormonal contraceptive use (can cause amenorrhea as a side effect) 5

• Anatomical causes:

  • Müllerian agenesis (for primary amenorrhea) 2
  • Uterine abnormalities 1

Clinical Implications

• Occasional menstrual irregularity is generally not concerning 5
• Persistent amenorrhea may indicate underlying health issues that require evaluation 5
• Low estrogen levels due to amenorrhea can lead to decreased bone mineral density and increased fracture risk 5, 1
• Patients with functional hypothalamic amenorrhea should be evaluated for eating disorders 1
• Athletes with amenorrhea require evaluation for Relative Energy Deficiency in Sport (RED-S) 1

Initial Evaluation

• Pregnancy test (first step in evaluation of secondary amenorrhea) 3, 1
• Serum hormone levels: FSH, LH, prolactin, and TSH 1, 2
• Physical examination to assess secondary sexual characteristics (especially for primary amenorrhea) 1
• Pelvic ultrasound to evaluate uterine and ovarian anatomy 1

Healthcare providers should consider pregnancy testing in cases of missed menses, especially when not using certain contraceptives like etonogestrel implants or depot medroxyprogesterone acetate 3.