What progestogen regimen is recommended for a non‑pregnant woman with abnormal uterine bleeding of unknown cause, without thrombo‑embolic disease or hormone‑sensitive cancer?

Progestogen Treatment for Abnormal Uterine Bleeding

For a non-pregnant woman with abnormal uterine bleeding of unknown cause (without thromboembolic disease or hormone-sensitive cancer), use cyclic oral medroxyprogesterone acetate 10-20 mg daily for 10-14 days per month, or consider a levonorgestrel-releasing intrauterine device (20 μg/day) as first-line therapy.

Treatment Algorithm

First-Line Options

Levonorgestrel-releasing IUD (LNG-IUD):

• Most effective medical option, comparable to endometrial ablation 1
• Reduces menstrual blood loss by 71-95% 1
• Releases 20 μg levonorgestrel daily with primarily local endometrial effects and minimal systemic absorption 1
• Particularly advantageous in patients where systemic hormones are relatively contraindicated
• Provides concurrent contraception

Cyclic Oral Progestins:

• Medroxyprogesterone acetate (MPA) 10-20 mg daily for 10-14 days per month 2, 3
• The 10-day protocol (days 16-25 of cycle) shows superior efficacy compared to 15-day protocol for regulating cycles and stopping bleeding 4
• Reduces bleeding by 87% 1
• Micronized progesterone 200 mg daily for 12-14 days per month is preferred when available due to lower cardiovascular and thrombotic risk 2

Acute Heavy Bleeding Management

For acute, severe bleeding requiring urgent control:

High-dose progestin regimen:

• Depo-medroxyprogesterone acetate 150 mg intramuscular injection PLUS
• Oral MPA 20 mg every 8 hours for 3 days (9 doses total) 5
• Mean time to bleeding cessation: 2.6 days with 100% efficacy within 5 days 5

Alternative Options

Combined hormonal contraceptives:

• Can be used if no contraindications to estrogen exist 6, 7
• Multiple formulations available (oral, patch, ring)
• Provide concurrent contraception

Tranexamic acid:

• Effective non-hormonal option reducing menstrual blood loss 8, 9
• No increased VTE risk 9
• Can be combined with hormonal methods

NSAIDs:

• 5-7 days of treatment for breakthrough bleeding 6
• Can be used adjunctively with hormonal methods
• Reduces menstrual blood loss through prostaglandin inhibition

Critical Considerations

Progestin Selection Hierarchy

1. Micronized progesterone (first choice): Lower cardiovascular and VTE risk with cyclic administration 2
2. Medroxyprogesterone acetate (second choice): Well-studied, effective
3. Dydrogesterone or norethisterone (alternatives): 2
4. Avoid anti-androgenic progestins in women with potential hypoandrogenism 2

Duration and Dosing Specifics

• Cyclic regimens: 10-14 days per month is essential for endometrial protection 3
• Shorter 10-day protocol (days 16-25) more effectively regulates cycles than 15-day protocol 4
• Continuous progestin: Requires minimum doses (norethisterone 1 mg, MPA 2.5 mg, dydrogesterone 5 mg daily) 2

Common Pitfalls to Avoid

Inadequate progestin duration: Less than 10 days per month provides insufficient endometrial protection and may not control bleeding effectively 3

Premature discontinuation: Allow 3 cycles of treatment before declaring failure, as the 10-day protocol shows optimal results by the third cycle 4

Ignoring contraindications: While the question specifies no thromboembolic disease or hormone-sensitive cancer, always verify pregnancy status before initiating treatment 6

Failure to investigate persistent bleeding: If bleeding continues despite appropriate medical therapy, further investigation with imaging or hysteroscopy is mandatory to exclude structural lesions 7

When Medical Therapy Fails

If bleeding persists after 3 months of appropriate medical management or if patient cannot tolerate hormonal therapy:

• Perform hysteroscopy to visualize endometrial cavity and diagnose focal lesions 7
• Consider endometrial ablation or hysterectomy 7
• Ensure endometrial sampling has been performed in women >45 years or those with risk factors for endometrial cancer 10

Monitoring and Follow-up

• Assess response after 3 menstrual cycles
• Check hemoglobin if heavy bleeding was present initially
• Counsel patients that irregular bleeding may occur initially with any hormonal regimen
• Patient satisfaction is typically high with progestin-only regimens when appropriately counseled 5