What is the initial workup for a 25-year-old female presenting to the emergency department (ED) with amenorrhea and episodic pelvic pain?

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Emergency Department Workup for Amenorrhea with Episodic Pelvic Pain in a 25-Year-Old Female

The initial emergency department workup for a 25-year-old female with amenorrhea and episodic pelvic pain must include a pregnancy test and pelvic ultrasound regardless of β-hCG level, as ectopic pregnancy must be ruled out immediately due to its life-threatening potential. 1, 2

Initial Assessment

Immediate Testing

  • Urine pregnancy test (qualitative β-hCG)
  • Serum quantitative β-hCG
  • Complete blood count to assess for anemia
  • Blood type and Rh status

Imaging

  • Pelvic ultrasound (transvaginal and transabdominal) regardless of β-hCG level
    • Important: Do not delay ultrasound based on low β-hCG levels, as ectopic pregnancies can occur at any β-hCG level 1
    • 36% of ectopic pregnancies diagnosed by bedside ultrasound have β-hCG levels below 1,000 mIU/mL 2

Differential Diagnosis to Consider

Pregnancy-Related Causes

  • Ectopic pregnancy (highest priority due to mortality risk)
  • Intrauterine pregnancy with threatened abortion
  • Molar pregnancy

Non-Pregnancy Causes

  • Polycystic ovary syndrome (PCOS)
  • Hypothalamic amenorrhea (stress, excessive exercise, eating disorders)
  • Hyperprolactinemia
  • Primary ovarian insufficiency
  • Anatomical abnormalities (obstructive uterovaginal anomalies) 3

Ultrasound Evaluation

What to Look For

  • Presence or absence of intrauterine pregnancy
  • Adnexal masses or free fluid suggesting ectopic pregnancy
  • Ovarian appearance (polycystic changes)
  • Uterine abnormalities (fibroids, congenital anomalies)
  • Endometrial thickness

Interpretation of Ultrasound Results

  1. Definitive intrauterine pregnancy: Presence of gestational sac with yolk sac or fetal pole in the uterus 1
  2. Definitive ectopic pregnancy: Extrauterine gestational sac with yolk sac or embryo 1
  3. Indeterminate ultrasound: No definitive intrauterine or ectopic pregnancy identified

Management Algorithm Based on Findings

If Pregnancy Test Positive

  1. Definitive intrauterine pregnancy:

    • Assess for viability and potential causes of pain (threatened abortion, subchorionic hemorrhage)
    • Consider obstetric consultation

  2. Definitive ectopic pregnancy:

    • Immediate gynecologic consultation
    • Assess hemodynamic stability
    • Prepare for possible surgical intervention or medical management with methotrexate 4

  3. Indeterminate ultrasound:

    • Critical point: Do not use β-hCG level to exclude ectopic pregnancy 1
    • Obtain gynecologic consultation or arrange close outpatient follow-up within 24 hours 1
    • Consider serial β-hCG measurements (but do not rely solely on these)
    • Administer Rh immunoglobulin to Rh-negative women 2

If Pregnancy Test Negative

  1. Initial laboratory workup:

    • TSH, prolactin, FSH, LH levels 5
    • Consider testosterone and DHEAS if signs of hyperandrogenism

  2. Based on hormone results:

    • High FSH/LH: Suggests primary ovarian insufficiency
    • Normal/Low FSH/LH with high testosterone: Suggests PCOS
    • High prolactin: Suggests hyperprolactinemia
    • Low/normal FSH/LH without hyperandrogenism: Suggests hypothalamic amenorrhea

Pitfalls to Avoid

  1. Do not delay ultrasound based on low β-hCG levels - ectopic pregnancies can present with any β-hCG level and can rupture even at very low levels 2

  2. Do not perform digital pelvic examination before ruling out ectopic pregnancy - may precipitate rupture 2

  3. Do not discharge patients with indeterminate ultrasound without definitive follow-up plans - 15% of patients with indeterminate ultrasounds are ultimately diagnosed with ectopic pregnancy 6

  4. Do not forget to administer Rh immunoglobulin to Rh-negative women with bleeding 2

  5. Do not underestimate the significance of abdominal pain - even without significant bleeding, it may indicate impending rupture of an ectopic pregnancy 4

Disposition Criteria

Criteria for Admission

  • Hemodynamic instability
  • Significant pain requiring parenteral analgesia
  • Confirmed ectopic pregnancy requiring immediate intervention
  • Significant bleeding

Criteria for Discharge with Follow-up

  • Stable vital signs
  • Mild symptoms controlled with oral medications
  • Definitive follow-up arranged within 24-48 hours
  • Clear return precautions provided

Remember that amenorrhea with pelvic pain in a woman of reproductive age should be considered an ectopic pregnancy until proven otherwise, as this represents the most immediately life-threatening condition in the differential diagnosis.

References

1
Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

2
Guideline

Evaluation and Management of Vaginal Bleeding in Pregnancy

Praxis Medical Insights: Practical Summaries of Clinical Guidelines, 2025

5
Research

Amenorrhea: an approach to diagnosis and management.

American family physician, 2013

6
Research

Outcome of patients with an indeterminate emergency department first-trimester pelvic ultrasound to rule out ectopic pregnancy.

Academic emergency medicine : official journal of the Society for Academic Emergency Medicine, 2004

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Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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