What is the initial management for a 29-year-old woman, not on birth control, presenting with new-onset abnormal uterine bleeding?

Initial Management of New-Onset Abnormal Uterine Bleeding in a 29-Year-Old Woman Not on Birth Control

Begin with a pregnancy test, complete blood count, TSH, and prolactin levels, followed by transvaginal ultrasound if structural pathology is suspected, then initiate treatment with combined oral contraceptives containing 30-35 μg ethinyl estradiol as first-line therapy once pregnancy and serious pathology are excluded. 1, 2

Immediate Diagnostic Workup

Essential laboratory tests include:

• Pregnancy test (beta-hCG) - This is the single most important initial test to exclude pregnancy 1
• Complete blood count - To assess for anemia from blood loss and evaluate for underlying coagulopathy 3
• Thyroid-stimulating hormone (TSH) - Thyroid dysfunction is a common reversible cause of abnormal bleeding 1
• Prolactin level - Hyperprolactinemia can cause ovulatory dysfunction 1

Consider screening for sexually transmitted infections, particularly in reproductive-aged women, as the CDC recommends excluding STIs before initiating treatment 2

When to Perform Imaging

Transvaginal ultrasound is indicated if:

• Structural pathology is suspected based on history or physical examination 1
• Symptoms persist despite appropriate initial medical treatment 1, 3
• The patient has risk factors for endometrial pathology 1

Transvaginal ultrasound is the preferred initial imaging modality with high sensitivity for detecting polyps, fibroids, and adenomyosis 1, 4. Saline infusion sonohysterography has 96-100% sensitivity for assessing intracavitary pathology if initial ultrasound is inconclusive 1.

Endometrial Sampling Considerations

At age 29, endometrial biopsy is NOT routinely required unless:

• The patient has risk factors for endometrial cancer (obesity, PCOS with chronic anovulation, diabetes) 5, 3
• Bleeding fails to respond to initial medical therapy 1, 3

Women younger than 35 years generally do not require endometrial sampling unless they have significant unopposed estrogen exposure or other risk factors 5, 3.

First-Line Medical Treatment

Initiate monophasic combined oral contraceptives containing 30-35 μg ethinyl estradiol with levonorgestrel or norgestimate once pregnancy and serious pathology are excluded 2, 6. This is the ACOG-recommended first-line treatment because it:

• Reduces menstrual blood loss by inducing regular shedding of a thinner endometrium 1, 2
• Decreases cramping 1, 2
• Provides additional benefits including acne improvement and reduced risk of endometrial and ovarian cancers 1, 2, 6

Managing Expectations and Follow-Up

Counsel the patient that unscheduled bleeding is common during the first 3-6 months of hormonal therapy and is generally not harmful 2, 6. This counseling reduces discontinuation rates 2.

If bleeding persists beyond 3-6 months despite COC therapy:

• Add NSAIDs (such as ibuprofen or naproxen) for 5-7 days during bleeding episodes 1, 2, 6
• Re-evaluate for underlying gynecological problems including structural lesions 2, 6
• Consider switching to a different COC formulation or alternative hormonal method 7

Safety Screening Before COC Initiation

Assess for contraindications to combined oral contraceptives:

• History of venous thromboembolism or thrombophilia 2, 6
• Active smoking in women ≥35 years (not applicable to this 29-year-old patient) 6
• Uncontrolled hypertension - measure baseline blood pressure 1, 2
• History of migraine with aura 2

COCs increase the risk of venous thromboembolism three to fourfold, though the absolute risk remains low (up to 4 per 10,000 woman-years) 2, 6.

Alternative Options if COCs Are Contraindicated

If combined hormonal contraception is contraindicated or not tolerated:

• Progestin-only contraception (pills, depot medroxyprogesterone acetate, or levonorgestrel IUD) 1
• NSAIDs alone during menses (reduces blood loss by 20-30%) 2, 3
• Tranexamic acid (reduces blood loss by 20-60%) if pregnancy is desired or hormones are contraindicated 2, 3

The levonorgestrel-releasing IUD is the most effective long-term medical treatment for heavy menstrual bleeding, reducing blood loss by 71-95% 6, 3.

Common Pitfalls to Avoid

• Do not delay pregnancy testing - pregnancy complications are the most common cause of abnormal bleeding in reproductive-age women 5, 3
• Do not perform endometrial biopsy routinely in women under 35 without risk factors, as endometrial cancer is extremely rare in this age group 5, 3
• Do not prescribe COCs without assessing thrombotic risk factors 2, 6
• Do not abandon treatment during the first 3 months of irregular bleeding, as this is expected and typically resolves 2, 7

When to Refer or Escalate Care

Consider gynecology referral if:

• Medical management fails after 3-6 months 1, 3
• Imaging reveals significant structural pathology (large fibroids, polyps) requiring surgical intervention 1, 3
• Endometrial biopsy shows hyperplasia with atypia or malignancy 1
• The patient desires definitive surgical management 3