Reproductive · Gynecology
The facts most likely to be tested
The PALM-COEIN classification system categorizes AUB into structural (Polyp, Adenomyosis, Leiomyoma, Malignancy) and non-structural (Coagulopathy, Ovulatory dysfunction, Endometrial, Iatrogenic, Not otherwise classified) causes.
Endometrial biopsy is the mandatory first-line diagnostic step for all women ≥45 years old with AUB to rule out endometrial hyperplasia or carcinoma.
Ovulatory dysfunction (AUB-O) is the most common cause of AUB in adolescents and is typically due to an immature hypothalamic-pituitary-ovarian axis.
Von Willebrand disease is the most common inherited bleeding disorder to consider in adolescents presenting with heavy menstrual bleeding (menorrhagia) since menarche.
Transvaginal ultrasound is the initial imaging modality of choice to evaluate for structural abnormalities such as leiomyomas or endometrial polyps.
Combined oral contraceptives (COCs) are the first-line medical therapy for AUB-O as they provide cycle control and stabilize the endometrium.
Acute, severe, hemodynamically unstable AUB is managed with high-dose IV estrogen to rapidly stabilize the endometrium and stop bleeding.
Vignette unlocked
A 48-year-old G2P2 woman presents to the clinic complaining of heavy, prolonged menstrual bleeding occurring every 24 days for the past six months. She reports passing large clots and feeling fatigued. Her physical exam reveals a palpable, irregularly enlarged uterus on bimanual examination. Her hemoglobin is 10.2 g/dL. She has no history of hormonal contraceptive use.
What is the most appropriate next step in the management of this patient?
Endometrial biopsy
This patient is ≥45 years old with abnormal uterine bleeding, necessitating an endometrial biopsy to rule out malignancy regardless of the suspected structural cause (leiomyoma).
Full handout
High yield triage
Etiology / Epidemiology
Common in adolescents (anovulation) and perimenopausal women. PALM-COEIN classification categorizes structural vs. non-structural causes.
Clinical Manifestations
Presents as menorrhagia (heavy) or metrorrhagia (irregular). Postmenopausal bleeding is endometrial cancer until proven otherwise.
Diagnosis
Transvaginal ultrasound is the initial imaging of choice. Endometrial biopsy is the gold standard for patients >45 or with risk factors.
Treatment
Combined oral contraceptives are first-line for ovulatory dysfunction. Do not use estrogen in patients with history of DVT/PE.
Prognosis
Most cases are managed medically. Endometrial hyperplasia with atypia carries a high risk of progression to malignancy.
Full handout
Epidemiology & Etiology
AUB is categorized by the PALM-COEIN system: Polyps, Adenomyosis, Leiomyoma, Malignancy (structural) and Coagulopathy, Ovulatory dysfunction, Endometrial, Iatrogenic, Not otherwise classified (non-structural). Obesity is a major risk factor for unopposed estrogen exposure. Anovulation is the most common cause in adolescents due to an immature HPO axis.
Pertinent Anatomy
The endometrium is the primary site of pathology. The myometrium is involved in adenomyosis and leiomyomas, which often cause bulky, irregular uteri. The cervix must be visualized to rule out local lesions.
Pathophysiology
Anovulatory AUB results from a lack of progesterone, leading to continuous estrogen stimulation of the endometrium without cyclic shedding. This causes unstable, proliferative tissue that eventually sloughs irregularly. Structural causes like leiomyomas increase surface area and interfere with normal uterine contractility.
Clinical Manifestations
Patients present with heavy, prolonged, or intermenstrual bleeding. Postmenopausal bleeding is a red flag requiring immediate evaluation for malignancy. Menorrhagia is defined as >80mL blood loss or >7 days of bleeding. Hemodynamic instability requires immediate stabilization and high-dose estrogen therapy.
Diagnosis
Initial workup includes beta-hCG to rule out pregnancy. Transvaginal ultrasound is the first-line imaging to assess endometrial thickness; a threshold of <4mm in postmenopausal women effectively rules out cancer. Endometrial biopsy is mandatory for all women >45 or those with persistent bleeding.
Treatment
Combined oral contraceptives (COCs) stabilize the endometrium and regulate cycles. For acute, severe bleeding, high-dose IV estrogen is used. Contraindications for estrogen include history of VTE, smoking in women >35, and estrogen-dependent cancers. Progestins are used if estrogen is contraindicated.
Prognosis
Most patients achieve cycle control with medical management. Endometrial hyperplasia requires close follow-up with repeat biopsy. Failure of medical therapy may necessitate hysterectomy or endometrial ablation.
Differential Diagnosis
Pregnancy: positive beta-hCG
Endometrial Cancer: postmenopausal bleeding
Leiomyoma: enlarged, mobile, irregular uterus
Adenomyosis: tender, symmetrically enlarged uterus
Von Willebrand Disease: history of heavy menses since menarche