3.1 Abnormal Uterine Bleeding & the FIGO PALM-COEIN Classification

Abnormal Uterine Bleeding & the FIGO PALM-COEIN Classification

Defining Normal and Abnormal Uterine Bleeding

Abnormal uterine bleeding (AUB) encompasses any variation from normal menstrual cyclicity, regularity, duration, or volume in non-pregnant reproductive-age individuals. The International Federation of Gynecology and Obstetrics (FIGO) replaced ambiguous terms like menorrhagia and metrorrhagia with standardized parameters:

Heavy menstrual bleeding (HMB) is defined as excessive blood loss interfering with physical, social, or emotional quality of life. Indicators include soaking ≥1 pad or tampon every hour for two consecutive hours, waking to change protection, passing clots >2.5 cm, or iron deficiency anemia. AUB is categorized into acute AUB (severe bleeding requiring immediate clinical intervention) and chronic AUB (bleeding abnormal in duration, volume, or frequency for the majority of the preceding 6 months).

The FIGO PALM-COEIN Classification System

FIGO classifies AUB into structural causes (PALM) identified on imaging or histology, and non-structural causes (COEIN) representing systemic or functional processes:

Structural Etiologies (PALM)

• Polyp (AUB-P): Hyperplastic overgrowths of endometrial glands and stroma around a vascular stalk. Polyps frequently produce intermenstrual spotting or HMB. Diagnosis is confirmed by transvaginal ultrasound (TVUS) or saline infusion sonohysterography (SIS), with hysteroscopic resection providing definitive therapy.
• Adenomyosis (AUB-A): Ectopic endometrial glands and stroma within the myometrium causing reactive smooth muscle hypertrophy. Clinically, patients present with HMB, dysmenorrhea, and a symmetrically enlarged, globular, "boggy," tender uterus. Ultrasound shows asymmetric myometrial thickening, subendometrial cysts, and junctional zone thickening ≥12 mm on MRI.
• Leiomyoma (AUB-L): Monoclonal smooth muscle tumors. FIGO stratifies fibroids into submucosal (L_SM) (Types 0–2), which distort the endometrial cavity and drive severe HMB, and other (L_O) (Types 3–8), which produce pelvic bulk symptoms, pelvic pressure, and urinary frequency.
• Malignancy & Hyperplasia (AUB-M): Atypical endometrial hyperplasia and adenocarcinoma must be excluded in high-risk patients, especially those aged ≥45 years or with chronic unopposed estrogen exposure.

Non-Structural Etiologies (COEIN)

• Coagulopathy (AUB-C): Encompasses systemic bleeding disorders. Von Willebrand disease (vWD) is the most common inherited coagulopathy, present in up to 20% of adolescents hospitalized for severe AUB. A structured screening tool is positive with heavy menses since menarche, postpartum hemorrhage, dental extraction bleeding, or frequent epistaxis.
• Ovulatory Dysfunction (AUB-O): Anovulatory cycles lead to absent luteal progesterone. Unopposed estrogen promotes persistent endometrial proliferation, resulting in fragile tissue breakdown with irregular, heavy bleeding. Causes include polycystic ovary syndrome (PCOS), perimenopause, adolescent HPO axis immaturity, thyroid disease, and hyperprolactinemia.
• Endometrial (AUB-E): Manifests in patients with regular ovulatory cycles experiencing HMB without structural lesions. It reflects primary endometrial dysfunction, such as deficient local vasoconstrictors (PGF2-alpha, endothelin-1) or accelerated fibrinolysis from excess tissue plasminogen activator.
• Iatrogenic (AUB-I): Bleeding induced by medical interventions, including copper IUDs, unscheduled spotting from progestin implants/IUS, combined contraceptives, systemic anticoagulants, or psychotropic medications.
• Not Otherwise Classified (AUB-N): Rare entities including uterine arteriovenous malformations (AVMs), myometrial hypertrophy, and cesarean scar defects (isthmocele or niche). FIGO 2018 places chronic endometritis under AUB-E.

Diagnostic Evaluation & Biopsy Indications

1. Laboratory Testing:
   • Urine or serum hCG (mandatory first line).
   • Complete blood count (CBC) to quantify anemia and thrombocytopenia.
   • Serum ferritin to detect depleted iron stores.
   • TSH and prolactin to rule out ovulatory endocrinopathies.
   • Coagulation panel (PT, aPTT, fibrinogen, vWF antigen, ristocetin cofactor) for adolescents with heavy bleeding since menarche or positive screening history.
2. Pelvic Imaging:
   • Transvaginal Pelvic Ultrasound (TVUS): Initial non-invasive modality to evaluate endometrial thickness, myometrial architecture, and adnexa.
   • Saline Infusion Sonohysterography (SIS): Superior to TVUS for delineating focal intracavitary polyps and submucosal fibroids.

Management: Acute vs. Chronic AUB

Acute Severe AUB Management

When acute, heavy uterine hemorrhage occurs without hemodynamic collapse, medical stabilization is prioritized:

• Intravenous Conjugated Equine Estrogen (CEE): 25 mg IV every 4 to 6 hours for up to 24 hours. CEE induces rapid endometrial proliferation and local vasospasm to arrest hemorrhage.
• High-Dose Oral Progestins: Medroxyprogesterone acetate 20 mg PO three times daily for 7 days (ACOG Committee Opinion 557).
• Combined Oral Contraceptives (COCs): A monophasic 35 mcg ethinyl estradiol pill three times daily for 7 days (ACOG Committee Opinion 557), after screening for estrogen contraindications.
• Tranexamic Acid (TXA): 1.3 g PO three times daily for 5 days, or 10 mg/kg IV (maximum 600 mg per dose) every 8 hours. TXA is an antifibrinolytic that stabilizes clots; contraindicated in active thromboembolic disease.
• Mechanical Tamponade & Surgery: An intrauterine Foley catheter balloon inflated with 30 to 50 mL sterile saline provides direct mechanical tamponade. Emergent dilation and curettage (D&C) is reserved for hemodynamic instability or failure of medical stabilization.

Chronic AUB Management

• Levonorgestrel 52 mg IUS: Most effective first-line non-surgical therapy for HMB, reducing blood loss by 70% to 90% at 6 months through profound local endometrial atrophy.
• Combined Hormonal Contraceptives: Suppress ovulation and thin the endometrium, reducing dysmenorrhea and blood loss.
• Oral Progestins: Daily norethindrone (5 mg) or medroxyprogesterone acetate (10 mg) prescribed continuously or during the luteal phase (days 14–25) prevents endometrial hyperplasia in anovulatory bleeding (AUB-O).
• Nonsteroidal Anti-Inflammatory Drugs (NSAIDs): Ibuprofen (600–800 mg TID) during menses inhibits cyclooxygenase, reducing menstrual flow by 25% to 40%.
• Surgical Modalities: Endometrial ablation (only for completed childbearing with a normal uterine cavity); myomectomy (hysteroscopic for Type 0/1 submucosal fibroids; laparoscopic/abdominal for other fibroids desiring uterine conservation); and hysterectomy (definitive cure for completed childbearing refractory to medical therapy).