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Abnormal (Dysfunctional) Uterine Bleeding (AUB)

BASICS

Description

  • Abnormal uterine bleeding (AUB) is uterine bleeding that is irregular in quantity, frequency, or duration.
  • May be acute or chronic (occurring >6 months).
  • The International Federation of Gynecology and Obstetrics (FIGO) now uses AUB instead of dysfunctional uterine bleeding (DUB).

Epidemiology

  • Most often affects adolescent and perimenopausal women.
  • Incidence: 5% of reproductive-aged women will see a doctor annually for AUB.
  • Prevalence: 3-30% of reproductive-aged women have AUB.

ETIOLOGY AND PATHOPHYSIOLOGY

  • Anovulation accounts for 90% of AUB.
  • In adolescents, AUB is often due to an immature hypothalamic-pituitary-ovarian (HPO) axis, causing anovulatory cycles.
  • The mnemonic PALM-COEIN describes causes of AUB in reproductive-aged women:
PALM (Structural Causes) COEIN (Non-structural Causes)
Polyp Coagulopathy
Adenomyosis Ovulatory disorders
Leiomyoma (fibroids) Endometrial causes
Malignancy and/or hyperplasia Iatrogenic causes
Not yet classified

Coagulopathy

  • 20% of heavy menstrual bleeding cases have bleeding disorders.
  • Most common: von Willebrand disease and thrombocytopenia.

Diseases Causing Ovulatory Dysfunction

  • Hyperparathyroidism, hypothyroidism, adrenal disorders, pituitary disease (e.g., prolactinoma), PCOS, eating disorders.

Medications (Iatrogenic Causes)

  • Anticoagulants, steroids, tamoxifen, hormonal contraception, copper IUD, antipsychotics (mostly first generation), postmenopausal hormone replacement therapy, antiemetics (metoclopramide, domperidone).

Other Causes

  • Ectopic pregnancy, threatened/incomplete abortion, hydatidiform mole, upper genital tract infections, advanced liver disease, chronic renal disease, nutritional deficiencies, inflammatory bowel disease, excessive weight gain, increased exercise.

Genetics

  • Unclear, but may include inherited hemostasis disorders.

RISK FACTORS

  • Unopposed estrogen therapy (#1 risk factor for endometrial cancer).
  • Age >40 years, obesity, PCOS, diabetes mellitus, nulliparity, early menarche or late menopause (>55 years), chronic anovulation or infertility.
  • History of breast cancer or endometrial hyperplasia.
  • Tamoxifen use.
  • Family history of gynecologic, breast, or colon cancer.
  • Thyroid disease.

GENERAL PREVENTION

  • No direct preventive measures for AUB.

DIAGNOSIS

History

  • Menstrual history: onset, severity (pad/tampon use, clots), timing (unpredictable or episodic) over 6 months.
  • Menopausal status.
  • Association with coitus, contraception, weight changes.
  • Gynecologic history: gravidity, parity, STI history, Pap smear results.
  • Review of systems: exclude pregnancy, bleeding disorders, stress, exercise, weight change, visual changes, headaches, galactorrhea.

Alert: Postmenopausal bleeding (>1 year after last period) mandates ruling out cancer.

Physical Exam

  • BMI, pallor, vital signs, visual field defects (pituitary lesion).
  • Vaginal discharge, hirsutism/acne, goiter, galactorrhea, purpura, ecchymosis.
  • Pelvic exam: uterine irregularities, Tanner stage, foreign bodies.
  • Rule out rectal or urinary tract bleeding.
  • Pap smear and STI testing.

Pediatric Considerations

  • Premenarchal bleeding: evaluate foreign bodies, abuse, infections, precocious puberty.

Differential Diagnosis

  • Refer to etiology and pathophysiology section.

DIAGNOSTIC TESTS & INTERPRETATION

Initial Tests

  • Urine hCG, CBC.
  • For heavy bleeding: type and crossmatch.
  • If coagulopathy suspected: PT, aPTT, fibrinogen; if abnormal → von Willebrand factor, ristocetin cofactor, factor VIII.
  • Hormonal tests if indicated: TSH, prolactin, FSH.
  • Infection screening: STI panel, KOH prep, vaginitis panel.
  • Possible congenital adrenal hyperplasia: 17-Hydroxyprogesterone.
  • PCOS suspicion: testosterone, DHEA-S.
  • Transvaginal ultrasound (TVUS): especially in postmenopausal AUB.

Endometrial Sampling (Based on ACOG 2018 Guidelines)

  • Recommended if endometrial thickness (ET) >4 mm in postmenopausal bleeding.
  • ET <4 mm with persistent/recurrent bleeding also needs evaluation.
  • Incidental ET >4 mm without bleeding usually no further evaluation unless risk factors.
  • TVUS, sonohysterography, hysteroscopy effective for intrauterine pathology in premenopausal women.

Follow-Up Tests & Special Considerations

  • Medical therapy may start in females <35 with low risk before biopsy.

Diagnostic Procedures

  • Pap smear if >21 years.
  • Endometrial biopsy (EMB):
  • Women >45 years with AUB.
  • Postmenopausal women with ET ≥4 mm.
  • Women 18-45 with unopposed estrogen history and failed medical management.
  • Any age with abnormal imaging findings.
  • Perform EMB after day 18 of cycle if known.
  • Hysteroscopy with biopsy if EMB negative but suspicion remains.

Test Interpretation

  • Pap smear: carcinoma or cervicitis.
  • EMB: proliferative/dyssynchronous endometrium (anovulation), hyperplasia (with or without atypia), adenocarcinoma.

TREATMENT

General Measures

  • NSAIDs (naproxen sodium 500 mg BID, mefenamic acid 500 mg TID, ibuprofen 600-1200 mg/day) reduce blood loss and pain.
  • Surgical approaches (including LNG-IUD) superior to medical therapy for long-term control.

Medications

First Line

  • Acute emergent nonovulatory bleeding:
  • Conjugated equine estrogen (Premarin) 25 mg IV q4h (max 6 doses) stops bleeding within 8h in 72%.
  • Oral Premarin 2.5 mg q6h controls bleeding in 12–24h.
  • Tranexamic acid (TXA) 1.3 g PO or 10 mg/kg IV TID.
  • Intrauterine tamponade: 26F Foley balloon with 30 mL saline.
  • D&C if no response after 2-4 Premarin doses or bleeding >1 pad/hr.

  • Change to oral contraceptive pill (OCP) or progestin for cycle regulation.

  • Acute nonemergent nonovulatory bleeding:

  • Monophasic combined OCPs with 35 µg estrogen TID for 7 days (88% success).

  • Medroxyprogesterone acetate 20 mg PO TID for 7 days (76% success in 3 days).

  • Nonacute nonovulatory bleeding:

  • Levonorgestrel IUD (Mirena): 71-95% decrease in blood loss, comparable to surgery.
  • Progestins: medroxyprogesterone acetate 10 mg/day for 5-10 days/month or Depo-Provera 150 mg q12 weeks.
  • OCPs: 20-35 µg estrogen plus progesterone (for anovulatory females <18 years not sexually active).
  • TXA 1.0–1.5 g PO TID (avoid in hypercoagulable states).

Precautions: Avoid estrogen if suspicion of endometrial hyperplasia/cancer, history of DVT, migraine with aura, or smoking >35 years.

Second Line

  • GnRH agonists (leuprolide) or antagonists (elagolix 300 mg BID with add-back therapy).
  • Danazol (200–400 mg/day max 9 months) limited by side effects.
  • Metformin or clomiphene for PCOS patients desiring ovulation/pregnancy.

Issues for Referral

  • Pediatric patients with unexplained bleeding: refer to pediatric endocrinology or adolescent gynecology.

Additional Therapies

  • Antiemetics with high-dose estrogen/progesterone.
  • Iron supplementation if anemia.

Surgery/Other Procedures

  • Hysterectomy: endometrial cancer, failed medical therapy, or other uterine pathology.
  • Endometrial ablation: less costly than hysterectomy, permanent, avoid if fertility desired.
  • Uterine artery embolization: refractory bleeding or confirmed fibroids.

Admission & Nursing Considerations

  • Manage acute anemia/hemodynamic instability with volume replacement and blood transfusion.
  • Monitor bleeding with pad counts and clot size.
  • Discharge when stable and bleeding controlled.

ONGOING CARE

Follow-Up Recommendations

  • Reevaluate 4–6 months after acute management.

Patient Monitoring

  • Keep menstrual diary if on estrogen or OCPs.

Diet

  • No restrictions.
  • 5% weight loss can induce ovulation in PCOS-related anovulation.

Patient Education

PROGNOSIS

  • Depends on underlying cause.
  • Most anovulatory cycles respond to medical therapy; surgery rarely needed.

COMPLICATIONS

  • Iron deficiency anemia.
  • Mood disorders.

REFERENCES

  1. Wouk N, Helton M. Abnormal uterine bleeding in premenopausal women. Am Fam Physician. 2019;99(7):435-443.
  2. Committee on Practice Bulletins—Gynecology. Practice Bulletin No. 128: diagnosis of abnormal uterine bleeding in reproductive-aged women. Obstet Gynecol. 2012;120(1):197-206.
  3. Khafaga A, Goldstein SR. Abnormal uterine bleeding. Obstet Gynecol Clin North Am. 2019;46(4):595-605.
  4. Marjoribanks J, Lethaby A, Farquhar C. Surgery versus medical therapy for heavy menstrual bleeding. Cochrane Database Syst Rev. 2016;2016(1):CD003855.
  5. Lethaby A, Irvine G, Cameron I. Cyclical progestogens for heavy menstrual bleeding. Cochrane Database Syst Rev. 2008;(1):CD001016.

See Also

  • Dysmenorrhea
  • Menorrhagia (Heavy Menstrual Bleeding)
  • Algorithm: Abnormal Uterine Bleeding

Codes

Code Description
ICD10 N93.9 Abnormal uterine and vaginal bleeding, unspecified
ICD10 N93.8 Other specified abnormal uterine and vaginal bleeding

Clinical Pearls

  • AUB is irregular uterine bleeding in absence of pregnancy or pathology—diagnosis of exclusion.
  • Anovulation accounts for 90% of cases.
  • Endometrial biopsy (EMB) indicated in:
  • Women >45 years with AUB.
  • Women 18-45 with history of unopposed estrogen and failed medical management.