## Investigation of Choice in PCOD **Key Point:** Transvaginal ultrasound is the gold standard imaging modality for diagnosing polycystic ovary syndrome (PCOD/PCOS) and is essential for meeting diagnostic criteria. ### Why Transvaginal Ultrasound? Transvaginal ultrasound detects the hallmark morphologic features of PCOD: - **Polycystic ovarian morphology (POM):** ≥12 follicles of 2–9 mm diameter in each ovary, OR ovarian volume ≥10 cm³ - **Increased stromal echogenicity** and stromal hypertrophy - Superior resolution compared to transabdominal approach ### Diagnostic Criteria (Rotterdam 2003) PCOD diagnosis requires **2 of 3** criteria: | Criterion | Details | |-----------|----------| | **Ovulatory dysfunction** | Oligomenorrhea or amenorrhea | | **Clinical or biochemical hyperandrogenism** | Hirsutism, acne, elevated testosterone | | **Polycystic ovarian morphology** | Ultrasound findings (transvaginal preferred) | **High-Yield:** Transvaginal ultrasound is **mandatory** to complete the Rotterdam diagnostic triad in this patient who already has ovulatory dysfunction (amenorrhea) and clinical hyperandrogenism (hirsutism, acne). ### Role of Other Investigations - **LH:FSH ratio:** Non-specific; elevated in ~70% of PCOD cases but not diagnostic. Used for assessment, not confirmation. - **Dexamethasone suppression test:** Used to exclude **Cushing syndrome** (which mimics PCOD) when clinical suspicion is high; not first-line. - **Adrenal CT:** Reserved for suspected adrenal tumors causing androgen excess; not indicated here with only mild testosterone elevation. **Clinical Pearl:** Always perform transvaginal ultrasound in reproductive-age women; transabdominal is acceptable only if transvaginal is contraindicated (e.g., virginity, patient refusal). [cite:Park 26e Ch 12]
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