A 35-year-old woman from Mumbai presents with 3 months of irregular, heavy, and prolonged menstrual bleeding. Cycles vary from 21 to 45 days, with bleeding lasting 8–10 days. She denies pelvic pain, dyspareunia, or postcoital bleeding. On examination, the uterus is normal in size and contour, with no adnexal masses. Pelvic ultrasound shows a normal uterus and ovaries with no structural abnormality. Endometrial thickness is 12 mm (measured in proliferative phase). Hemoglobin is 10.1 g/dL. Coagulation profile and thyroid function tests are normal. What is the most likely diagnosis?

Explanation

## Clinical Diagnosis: Anovulatory Dysfunctional Uterine Bleeding ## Key Clinical Features in This Case **Key Point:** This patient presents with **anovulatory DUB**, the most common cause of abnormal uterine bleeding in reproductive-age women (80% of cases). The diagnosis is made by **exclusion** of structural, coagulation, and endocrine causes. ### Diagnostic Criteria Met: | Feature | Finding | Significance | |---------|---------|---------------| | **Cycle irregularity** | 21–45 days (anovulatory pattern) | Absence of ovulation → no corpus luteum → no progesterone | | **Heavy, prolonged bleeding** | 8–10 days | Unopposed estrogen stimulates endometrial proliferation without cyclic shedding | | **Normal structural exam** | Uterus normal size/contour; no adnexal masses | Rules out fibroids, adenomyosis, malignancy | | **Normal ultrasound** | No fibroid, no adenomyosis, normal ovaries | Confirms structural normality | | **Normal endometrial thickness** | 12 mm in proliferative phase | Benign; rules out hyperplasia/malignancy (though biopsy not needed at age 35 without risk factors) | | **Normal hemostasis** | Coagulation profile normal | Rules out von Willebrand disease, thrombocytopenia | | **Normal thyroid function** | TSH normal | Rules out hypothyroidism (a reversible cause) | | **Age 35 (reproductive)** | Reproductive age | DUB is most common in teens and perimenopausal women; also seen in reproductive years | **High-Yield:** DUB is a **diagnosis of exclusion**. Once structural, coagulation, and endocrine causes are ruled out, anovulatory DUB is the default diagnosis. ## Pathophysiology of Anovulatory DUB ```mermaid flowchart TD A[Absent Ovulation]:::outcome --> B[No Corpus Luteum]:::outcome B --> C[No Progesterone Secretion]:::outcome C --> D[Unopposed Estrogen Stimulation]:::outcome D --> E[Continuous Endometrial Proliferation]:::outcome E --> F[Disorganized, Fragile Endometrium]:::outcome F --> G[Irregular, Heavy, Prolonged Bleeding]:::outcome ``` **Clinical Pearl:** In anovulatory cycles, the endometrium is **not shed cyclically** (as it would be with progesterone). Instead, it undergoes continuous proliferation and random, incomplete shedding, leading to unpredictable heavy bleeding. ## Why Other Options Are Incorrect ### Option A: Uterine Fibroids - **Why wrong:** Ultrasound is **normal**; no fibroid is visualized. - Fibroids typically cause regular or slightly prolonged cycles (if submucosal), not the irregular 21–45 day pattern seen here. - Fibroids would be visible on ultrasound if present. ### Option C: Adenomyosis - **Why wrong:** Adenomyosis causes **dysmenorrhea** (pelvic pain) as a cardinal feature; this patient denies pain. - Adenomyosis also causes a uniformly enlarged, boggy uterus; this patient's uterus is normal in size. - Ultrasound findings (normal uterus, normal endometrial thickness) are inconsistent with adenomyosis. - Adenomyosis is more common in women >40 years and multiparous women. ### Option D: Endometrial Polyp - **Why wrong:** Endometrial polyps typically cause **intermenstrual bleeding** or **postmenopausal bleeding**, not irregular cycles with anovulation. - Polyps cause focal endometrial thickening or a discrete mass; this patient has uniform endometrial thickness (12 mm). - Polyps are usually <2 cm and may not be visible on standard ultrasound; they are better seen on saline infusion sonography (SIS) or hysteroscopy. - Polyps do not explain the anovulatory pattern (irregular cycles 21–45 days). ## Management of Anovulatory DUB **First-line medical therapy:** 1. **Progestins** (first-line): Medroxyprogesterone acetate 10–20 mg daily for 10–14 days to induce withdrawal bleeding and stabilize the endometrium. 2. **Combined oral contraceptive pills (COCPs)**: Regulate cycles and reduce menstrual blood loss by 40–50%. 3. **Tranexamic acid or NSAIDs**: For symptom control if hormonal therapy is contraindicated. **Surgical therapy** (if medical therapy fails): Endometrial ablation or hysterectomy (rare at age 35).