What is the initial workup for a patient presenting with irregular menses (oligomenorrhea or amenorrhea)?

Initial Workup for Irregular Menses (Oligomenorrhea or Amenorrhea)

The initial workup for irregular menses should include a thorough menstrual history, targeted physical examination, pregnancy testing, and baseline hormonal laboratory tests including FSH, LH, estradiol, prolactin, and TSH to identify the underlying cause. 1, 2, 3

Definition and Classification

• Oligomenorrhea is defined as menstrual cycles occurring at intervals greater than 35 days 1, 3
• Amenorrhea is classified as:
  • Primary amenorrhea: absence of menarche by age 15 or 3 years after thelarche 2, 3
  • Secondary amenorrhea: cessation of previously regular menses for 3 months or previously irregular menses for 6 months 1, 3

Initial Clinical Assessment

History

• Detailed menstrual history:
  • Age of menarche, regularity of cycles, duration of irregularity 1, 3
  • Document cycle length (normal: 21-35 days) 4
  • Menstrual flow characteristics (duration, amount) 4
• Medical history:
  • Weight changes, eating patterns, exercise habits 1, 3
  • Medication use (including hormonal contraceptives) 1, 3
  • Chronic illness, prior surgeries 2, 3
• Symptoms suggesting specific etiologies:
  • Hirsutism, acne (PCOS) 5, 6
  • Galactorrhea (hyperprolactinemia) 1, 3
  • Hot flashes, vaginal dryness (primary ovarian insufficiency) 2, 3
  • Headaches, visual changes (pituitary disorders) 2

Physical Examination

• Vital signs including blood pressure 5, 6
• BMI calculation (obesity is associated with PCOS and menstrual irregularities) 1, 5
• Signs of androgen excess:
  • Hirsutism (using Ferriman-Gallwey score) 1
  • Acne, male-pattern hair loss 5
• Thyroid examination 2, 3
• Breast examination (galactorrhea) 1
• Pelvic examination to assess:
  • Outflow tract abnormalities 2, 3
  • Signs of estrogen status (vaginal atrophy) 1

Laboratory Testing

First-line Laboratory Tests

• Pregnancy test (to exclude pregnancy as cause of amenorrhea) 1, 2, 3
• Hormonal assessment:
  • Follicle-stimulating hormone (FSH) and luteinizing hormone (LH) 1, 2
    • High FSH/LH: suggests primary ovarian insufficiency
    • LH/FSH ratio >2: suggests PCOS 1
  • Thyroid-stimulating hormone (TSH) to rule out thyroid dysfunction 1, 2, 3
  • Prolactin to rule out hyperprolactinemia 1, 2, 3
  • Estradiol levels (particularly in adolescents with primary amenorrhea or delayed puberty) 1

Additional Testing Based on Initial Findings

• For suspected PCOS:
  • Total and free testosterone levels 5, 6
  • Metabolic screening: fasting glucose, HbA1c, lipid profile 5, 6
  • Consider glucose tolerance test 6
• For suspected primary ovarian insufficiency:
  • Repeat FSH/LH measurements 2, 3
  • Consider karyotype analysis (especially in young patients) 2, 3

Imaging Studies

• Pelvic ultrasonography:
  • Indicated when clinical features or hormonal tests suggest ovarian pathology 1
  • Transvaginal ultrasound is more sensitive than transabdominal for identifying structural abnormalities 1
  • Evaluates for PCOS features (ovarian volume, follicle count) 5
  • Assesses endometrial thickness 1
• Additional imaging based on suspected etiology:
  • MRI of pituitary if hyperprolactinemia is present or other pituitary disorder is suspected 1, 2

Common Pitfalls and Considerations

• Don't assume that all irregular menses are due to PCOS; systematic evaluation is essential 2, 3
• Patients with amenorrhea due to hypothalamic causes should be evaluated for disordered eating and low bone density 1, 3
• Women with PCOS are at increased risk for cardiometabolic disorders including insulin resistance, prediabetes, dyslipidemia, and metabolic syndrome 5, 6
• The severity of menstrual dysfunction correlates with cardiometabolic risk - women with amenorrhea show higher prevalence of insulin resistance, prediabetes, and dyslipidemia compared to those with oligomenorrhea 6
• Patients with primary ovarian insufficiency can maintain unpredictable ovarian function and should not be presumed infertile 2, 3
• Consider medication-induced causes of irregular menses, including certain antipsychotics, antiepileptics, and hormonal contraceptives 1

By following this systematic approach to the evaluation of irregular menses, clinicians can identify the underlying cause and initiate appropriate management to address both the menstrual irregularity and any associated health risks.