Abnormal Uterine Bleeding (AUB)

Definition

• Sabiston Textbook of Surgery, p. 2794
• Rosen's Emergency Medicine, p. 1419

Normal vs. Abnormal Menstrual Patterns

PALM-COEIN Classification (FIGO 2011)

PALM - Structural Causes

Diagnosed via imaging or histologic evaluation.

COEIN - Non-Structural Causes

The term "dysfunctional uterine bleeding" is obsolete and should not be used.

• Rosen's Emergency Medicine, p. 1420

Causes by Age Group

• Robbins & Kumar Basic Pathology, Table 17.2

Epidemiology and Pathophysiology

• AUB affects 10-30% of women of reproductive age.
• About 20% is postmenarchal bleeding in adolescents due to hypothalamic-pituitary-ovarian (HPO) axis immaturity.
• About 50% is perimenopausal from incipient ovarian failure.
• 75% of cases have no demonstrable organic cause and are associated with anovulation.

Anovulatory Bleeding Mechanism

• Estrogen withdrawal bleeding - when estrogen levels drop
• Estrogen breakthrough bleeding - when estrogen levels are high but fluctuating
• Goldman-Cecil Medicine, p. 2555

Dysfunctional (Non-Structural) Causes

• Anovulation from: pituitary tumors secreting prolactin, PCOS, obesity, malnutrition, chronic systemic disorders
• Inadequate luteal phase (insufficient progesterone from corpus luteum)
• Robbins & Kumar Basic Pathology, p. 596

Clinical Manifestations

• Heavy menstrual bleeding (HMB): excessive menses interfering with physical, social, emotional, or material quality of life
• Intermenstrual bleeding (IMB): between periods
• Postcoital bleeding (PCB): after intercourse (suggests cervical pathology)
• Postmenopausal bleeding (PMB): any bleeding 12+ months after cessation of menses - must always be considered malignant until proven otherwise

Diagnosis

History

• Amount, duration, and pattern of blood loss
• Relationship to menstrual cycle
• Medication use (OCP, anticoagulants, tamoxifen)
• Family history of bleeding disorders
• Risk factors for endometrial cancer (obesity, diabetes, nulliparity, age >55)
• Sexual activity, STI risk factors

Physical Examination

• Signs of hemodynamic instability (acute heavy bleeding)
• Signs of anemia (fatigue, pallor)
• PCOS signs: obesity, acne, hirsutism, acanthosis nigricans
• Thyroid examination
• Skin: petechiae, ecchymoses (coagulopathy)
• Speculum and bimanual examination for cervical/vaginal lesions, uterine size

Laboratory Tests

1. Pregnancy test (urine/serum beta-hCG) - essential in all reproductive-age women
2. CBC + platelet count - assess anemia, thrombocytopenia
3. Coagulation studies (PT, aPTT) - if coagulopathy suspected
4. Von Willebrand disease screen - up to 20% of women with HMB have underlying coagulopathy; vWD is the most common (~13%)
5. TSH - hypothyroidism associated with AUB
6. Fasting glucose - endocrine assessment
7. Prolactin level
8. STI screening (Chlamydia) - if risk factors present

• Rosen's Emergency Medicine, p. 1420
• Goldman-Cecil Medicine, p. 2555

Imaging

• Transvaginal ultrasound (TVUS): first-line imaging
  • Can detect fibroids, endometrial thickening, focal masses
  • Endometrial thickness <4-5 mm in postmenopausal women reliably excludes endometrial cancer
  • Thickness >4 mm in postmenopausal women warrants biopsy
  • Note: recent data shows the 4 mm cutoff may underdiagnose endometrial cancer in Black patients
• Saline infusion sonography / SIS: improves detection of intrauterine pathology
• MRI: for detailed fibroid mapping

Endometrial Biopsy - Indications

• All women age 45 or older with AUB
• Women <45 years with: obesity/anovulation (unopposed estrogen exposure), persistent or treatment-refractory AUB, elevated familial cancer risk
• Any postmenopausal woman with endometrial thickness >4 mm, suspected focal lesion, or persistent bleeding despite normal ultrasound
• Women on tamoxifen (risk of polyps, hyperplasia, and cancer 10-40%)
• Sabiston Textbook of Surgery, p. 2795
• Bailey and Love's Surgery, p. 1605

Hysteroscopy

Management

1. Hemodynamically Unstable / Acute Profuse Bleeding

• IV fluid resuscitation and blood products
• IV conjugated equine estrogen 25 mg IV every 4-6 hours (up to 3 doses) until bleeding ceases
• Progestin (MPA 5-10 mg orally) should be started simultaneously
• If IV estrogen fails: urgent dilation and curettage (D&C)
• Surgical options: uterine artery embolization, endometrial ablation, or hysterectomy

2. Anovulatory Bleeding (Stable)

• Combined oral contraceptive pill every 6 hours for 5-7 days (off-label); bleeding should cease within 24 hours
• Warn patients: expect heavy withdrawal bleed 2-4 days after stopping therapy

• Combined OCP cyclically (if no fertility desired)
• Progestins: medroxyprogesterone acetate 5-10 mg for 10 days, or norethindrone 5 mg daily
• Levonorgestrel IUD: effective for both HMB and dysmenorrhea

• Ovulation induction

3. Ovulatory AUB

• NSAIDs (anti-prostaglandin effect)
• Hormonal therapy (OCP, progestins)
• Tranexamic acid (antifibrinolytic)
• Levonorgestrel IUD

4. Structural Causes

5. Surgical Options (Reserved for Failure of Medical Therapy)

• Endometrial ablation: effective but not 100%; ~29% proceed to hysterectomy by 60 months
• Uterine artery embolization (UAE): for fibroids; ~31% ultimately undergo hysterectomy
• Hysterectomy: definitive treatment; reserved for those who fail or cannot tolerate medical therapy, or when malignancy is confirmed

Endometrial sampling must be performed before hysterectomy in patients with AUB.

• Berek & Novak's Gynecology, p. 1411
• Goldman-Cecil Medicine, p. 2556

Special Considerations

Postmenopausal Bleeding

• Most common cause: endometrial atrophy
• Most feared cause: endometrial cancer (90% of endometrial cancer presents with PMB)
• Other causes: polyps, fibroids, adenomyosis, HRT, anticoagulants
• Every case of PMB requires investigation: TVUS + endometrial biopsy

Tamoxifen Use

• Risk of uterine abnormalities in 10-40%: polyps, hyperplasia, cancer, and uterine sarcomas
• These women require heightened surveillance

Adolescents

• Von Willebrand disease and other coagulopathies must be considered at first presentation
• HPO axis immaturity is common; manage conservatively initially

Postmenopausal women on HRT

• Irregular or unscheduled bleeding after the first 3 months warrants endometrial biopsy

Summary Flowchart

AUB → Exclude Pregnancy
       ↓
   Assess Hemodynamics
       ↓
   Stable?  ─── No → Resuscitate + IV Estrogen + D&C/Surgery
       ↓ Yes
   History + Exam + Labs (CBC, TSH, coags, pregnancy test)
       ↓
   Pelvic Ultrasound (TVUS)
       ↓
   Endometrial Biopsy (if ≥45 yrs, risk factors, or PMB with thickness >4mm)
       ↓
   PALM-COEIN Classification
       ↓
   Structural (PALM) → Targeted therapy
   Non-structural (COEIN) → Medical management (OCP/Progestin/LNG-IUD/Tranexamic acid)
       ↓
   Failure of medical therapy → Ablation/UAE/Hysterectomy

• Goldman-Cecil Medicine (International Edition), pp. 2555-2556
• Rosen's Emergency Medicine, pp. 1419-1421
• Sabiston Textbook of Surgery, pp. 2793-2795
• Berek & Novak's Gynecology, p. 1411
• Robbins & Kumar Basic Pathology, pp. 595-596
• Bailey and Love's Short Practice of Surgery (28th ed.), pp. 1605-1606