Gestational trophoblastic diseases (GTD) are a group of interrelated disorders characterized by abnormal and excessive proliferation of placental trophoblasts. The routine use of ultrasonography (USG) in early pregnancy has enabled the exclusion of normal pregnancy and the recognition of molar pregnancy as early as the first trimester. A definitive diagnosis is made by histopathologic evaluation of the specimen obtained after vacuum curettage. 

Gestational trophoblastic diseases are classified as premalignant/benign and malignant. Benign GTH consists of placental site nodules, exaggerated placental sites, and mole hydatiform (complete and partial). Complete and partial molar pregnancy are the most common GTHs. They have the potential for local invasion and distant metastasis. Malignant forms include choriocarcinoma (CC), placental site trophoblastic tumor (PSTT), and its variant epithelioid trophoblastic tumor (ETT), which are classified under gestational trophoblastic neoplasia (GTN).

Human chorionic gonadotropin (hCG) is used in diagnosing, following up on, and evaluating responses to treatment.

Gestational trophoblastic neoplasia usually responds well to chemotherapy. Low-risk GTN (FIGO Stage I-III: score <7) is treated with single-agent chemotherapy but may require additional agents; overall survival approaches 100%. High-risk GTN (FIGO Stage II-III: score ≥7 and Stage IV) is treated with multi-agent chemotherapy with or without adjuvant surgery for excision of resistant disease foci or radiotherapy for brain metastases, resulting in a survival rate of approximately 90%. Afterwards, fertility is preserved, and good pregnancy outcomes are observed. This chapter aims to provide information on the approach, treatment, and new treatment strategies for GTN.