What are the current guidelines for evaluating and managing abnormal uterine bleeding in reproductive‑age women?

Abnormal Uterine Bleeding: Guidelines and Management

Use the PALM-COEIN classification system to systematically evaluate all reproductive-age women with abnormal uterine bleeding, starting with medical management (combined hormonal contraception or progestin-only therapy) as first-line treatment for ovulatory dysfunction, and reserve surgical intervention for medical treatment failures or significant structural lesions. 1

Classification Framework

The PALM-COEIN system categorizes AUB into:

Structural causes (PALM):

• Polyp
• Adenomyosis
• Leiomyoma (submucosal or other)
• Malignancy and hyperplasia

Non-structural causes (COEIN):

• Coagulopathy
• Ovulatory dysfunction
• Endometrial
• Iatrogenic
• Not yet classified

This framework ensures systematic evaluation and prevents missed diagnoses 1.

Initial Evaluation

History - Specific Red Flags to Identify

• Pregnancy status - Always rule out first with β-hCG
• Bleeding pattern - Heavy, irregular, intermenstrual, or postcoital
• Age extremes - Adolescence (anovulation common) or perimenopause (malignancy risk increases)
• Coagulopathy indicators - Personal/family history of bleeding disorders, bruising, epistaxis
• Hyperandrogenic symptoms - Hirsutism, acne (PCOS)
• Thyroid dysfunction - Weight changes, temperature intolerance
• Hyperprolactinemia - Galactorrhea, headaches, visual changes
• Medications - Anticoagulants, hormonal therapies, antipsychotics
• Endometrial cancer risk factors - Obesity, diabetes, unopposed estrogen exposure, Lynch syndrome 1, 2

Laboratory Testing Algorithm

Essential for all patients:

• Pregnancy test (β-hCG)
• Complete blood count (assess anemia severity)

Selective based on clinical suspicion:

• TSH and prolactin (if menstrual irregularity suggests ovulatory dysfunction)
• Coagulation studies (if personal/family bleeding history or heavy bleeding since menarche)
• Endometrial biopsy (see criteria below) 1, 2

Endometrial Sampling Indications

Perform endometrial biopsy when:

• Age ≥45 years with AUB
• Age <45 years with risk factors for endometrial cancer (obesity, diabetes, PCOS, unopposed estrogen exposure, Lynch syndrome)
• Failed medical management at any age
• Persistent irregular bleeding

Critical caveat: Endometrial biopsy is preferred over dilation and curettage due to lower invasiveness, safety profile, and cost, though sensitivity varies with lesion type and distribution 1, 2.

Imaging Strategy

First-Line: Transvaginal Ultrasound

Transvaginal ultrasound is the initial imaging modality for all reproductive-age women with AUB (use transabdominal in virgins, though less sensitive) 3, 2.

Key limitation: Endometrial thickness has no validated upper limit cutoff in premenopausal women - even thickness <5mm does not exclude polyps or other pathology. Focus instead on abnormal echogenicity and texture 3.

TVUS diagnostic performance:

• Adenomyosis: 82.5% sensitivity, 84.6% specificity (but drops to 33.3% sensitivity when coexisting leiomyomas present) 3

Second-Line: Saline Infusion Sonohysterography

Use when TVUS shows focal endometrial abnormality or findings are inconclusive 1, 3.

Performance characteristics:

• Sensitivity: 96-100%
• Negative predictive value: 94-100%
• Superior for confirming intracavitary lesions 1

Third-Line: MRI Pelvis

Reserve MRI for:

• Incomplete uterine visualization on ultrasound
• Indeterminate ultrasound findings
• Pre-treatment leiomyoma mapping
• Suspected malignancy (differentiates benign from malignant with 79-89% sensitivity/specificity for endometrial cancer)
• Adenomyosis assessment when coexisting leiomyomas obscure ultrasound (78% sensitivity, 93% specificity) 3

Use gadolinium-based IV contrast and include diffusion-weighted sequences - abnormal diffusion signal and irregular endometrial-myometrial interface are most helpful for distinguishing benign from malignant pathology 3.

Medical Management

First-Line Pharmacologic Options

For ovulatory dysfunction-related AUB, initiate medical therapy before considering surgery 1, 4:

Hormonal options:

• Combined oral contraceptives (multi-dose regimens for acute bleeding)
• Progestin-only contraception (oral progestins, levonorgestrel IUD)

Non-hormonal option:

• Tranexamic acid

For acute severe bleeding:

• Intravenous conjugated equine estrogen (hemodynamically unstable patients)
• Multi-dose combined oral contraceptives
• Oral progestins 4

Selection criteria: Base choice on contraindications, medical history, and patient preference. The levonorgestrel IUD provides excellent long-term control for heavy menstrual bleeding 5, 6.

Transition to Maintenance

Once acute bleeding controlled, transition to long-term maintenance therapy to prevent recurrence 4.

Surgical Management

Indications for Surgery

Proceed to surgical intervention when:

• Medical management fails
• Medical therapy contraindicated or not tolerated
• Hemodynamic instability unresponsive to medical therapy
• Concomitant significant intracavitary lesions (polyps, submucosal fibroids)
• Patient preference after counseling 1, 4

Surgical Options by Indication

For structural lesions:

• Hysteroscopic polypectomy (endometrial polyps)
• Hysteroscopic myomectomy (submucosal fibroids)
• Abdominal/laparoscopic myomectomy (intramural/subserosal fibroids, fertility desired)

For medical treatment failures without structural pathology:

• Endometrial ablation (fertility not desired, benign pathology confirmed) 7
• Hysterectomy (definitive treatment, fertility not desired)

Critical consideration: Endometrial ablation requires confirmed benign pathology and completed childbearing. Success rates are maximized with proper patient selection 7.

Common Pitfalls to Avoid

1. Assuming normal endometrial thickness excludes pathology in premenopausal women - thickness criteria only apply to postmenopausal bleeding 3

2. Missing coagulopathy - particularly in adolescents with heavy bleeding since menarche; consider von Willebrand disease and platelet disorders 1

3. Delaying endometrial sampling in high-risk patients - obesity, diabetes, and PCOS significantly increase endometrial cancer risk even in younger women 2

4. Overlooking medication-induced bleeding - anticoagulants (especially rivaroxaban) substantially increase AUB risk and may require platelet transfusion goal adjustments 8

5. Performing endometrial ablation without excluding malignancy - always confirm benign pathology first 7

6. Missing adenomyosis on ultrasound when leiomyomas present - sensitivity drops dramatically; consider MRI if clinical suspicion high 3

Algorithmic Approach Summary

1. Rule out pregnancy (β-hCG)
2. Classify using PALM-COEIN (history, exam, labs)
3. Image with transvaginal ultrasound (first-line)
4. Sample endometrium if indicated (age ≥45 or risk factors)
5. Initiate medical management (hormonal or tranexamic acid)
6. Advance imaging if needed (sonohysterography or MRI)
7. Surgical intervention (if medical failure or structural lesions)
8. Maintain long-term therapy (prevent recurrence)

This systematic approach prioritizes quality of life through minimally invasive interventions while ensuring malignancy is not missed 2, 5, 6.