A 28-year-old woman from rural Maharashtra presents to the gynaecology outpatient department with vaginal bleeding and lower abdominal pain for 3 weeks. She reports amenorrhoea for 2 months. On examination, the uterus is enlarged disproportionately (size consistent with 16 weeks gestation) but soft. Serum β-hCG is markedly elevated at 450,000 mIU/mL. Transvaginal ultrasound shows a heterogeneous echogenic mass filling the uterine cavity with multiple small cystic spaces ('bunch of grapes' appearance) and no fetal parts. There is no evidence of theca lutein cysts. What is the most likely diagnosis?

Explanation

## Diagnosis: Complete Hydatidiform Mole ### Clinical Presentation **Key Point:** The clinical triad of markedly elevated β-hCG (often >100,000 mIU/mL), uterine enlargement disproportionate to gestational age, and vaginal bleeding is pathognomonic for complete mole. ### Ultrasound Findings The **'bunch of grapes'** appearance (multiple small anechoic spaces within echogenic tissue) is the classic ultrasound hallmark of complete hydatidiform mole. This represents hydropic villi. ### Karyotype & Pathology | Feature | Complete Mole | Partial Mole | |---------|---------------|---------------| | Karyotype | 46,XX (90%) or 46,XY (10%) — diploid, biparental | 69,XXX or 69,XXY — triploid, diandric | | Fetal tissue | Absent | Present (rudimentary fetus/amnion) | | β-hCG level | Very high (>100,000) | Moderately elevated | | Theca lutein cysts | Common (>50%) | Rare | | Malignant potential | 15–20% (choriocarcinoma) | 1–5% | | Uterine size | Larger than dates | Smaller than dates | **High-Yield:** Complete moles are entirely of paternal origin (androgenetic) — either duplication of a single sperm (90%) or fertilization by two sperm (10%). Partial moles are triploid with diandric contribution. ### Why Complete Mole Here 1. **No fetal parts** on ultrasound → rules out partial mole 2. **Markedly elevated β-hCG** (450,000) → typical of complete mole 3. **Uterus enlarged beyond dates** → complete mole 4. **'Bunch of grapes' pattern** → diagnostic of complete mole 5. **No theca lutein cysts mentioned** → less common in complete mole but absence does not exclude it ### Management **Clinical Pearl:** After evacuation by suction curettage, close follow-up with serial β-hCG is mandatory because 15–20% of complete moles progress to persistent gestational trophoblastic neoplasia (PGTN) or choriocarcinoma. **Mnemonic: CHOP** — **C**omplete mole has **H**igh hCG, **O**ften no fetus, **P**aternal origin only.