Background: Gestational Trophoblastic disease is an umbrella term used to describe the heterogeneous group of interrelated lesions that arise from abnormal proliferation of placental trophoblast. They can be benign or malignant. All forms of Trophoblastic diseases produce beta hCG (human chorionic gonadotrophin).

Materials and Methods: This institution-based, observational, prospective study was conducted from January 2023 to March 2024 at Medical College, Kolkata. A total of 83 patients were included.

Results: Serial transvaginal color Doppler assessment of the uterine artery provides diagnostic information that is both earlier and incrementally more informative than standard serum beta-hCG surveillance alone in predicting progression to gestational trophoblastic neoplasia after molar evacuation. Doppler indices — particularly the Week 2 pulsatility index — achieved high discriminatory accuracy, produced a clinically meaningful reclassification improvement over hCG-based risk models, and identified impending GTN a median of 18 days before FIGO biochemical criteria were met. Taken together, these findings support incorporating scheduled Doppler ultrasound as a structured adjunct — rather than an incidental addition — to biochemical follow-up protocols for molar pregnancy, with the potential to shorten time to diagnosis and treatment initiation in patients progressing to GTN.