 Introduction/Background Gestational trophoblastic disease (GTD), or abnormal proliferation of placental trophoblastic tissue, is a rare complication of pregnancy. There is considerable variation in the worldwide distribution of GTD, with the highest frequencies reported in Asia and the Middle East and lower rates on the order of 1 per 1,000 pregnancies in Europe and North America [1,2]. Extremes of maternal age and personal history of GTD are known risk factors [1-3]. The American College of Radiology seeks and encourages collaboration with other organizations on the development of the ACR Appropriateness Criteria through society representation on expert panels. Participation by representatives from collaborating societies on the expert panel does not necessarily imply individual or society endorsement of the final document. Reprint requests to: publications@acr.org Gestational Trophoblastic Disease On the whole, women with GTD have a favorable prognosis for cure with early adequate treatment, despite the presence of metastatic disease in some patients. Patients with benign but premalignant lesions are managed with uterine evacuation and enrolled in postoperative hCG surveillance [16]. Hysterectomy in patients not opting to preserve fertility does not eradicate risk of postmolar GTN [16-19]. If malignant GTN other than ETT or PSTT is suspected or has been established, further evaluation for potential metastatic lesions is initiated, clinical risk factors determined, and patients stratified into low- or high-risk groups based on the modified World Health Organization (WHO) prognostic scoring system as adapted by and combined with the international Federation of Gynecology and Obstetrics (FIGO) anatomic staging system [2,20]. This combines anatomic staging with assessment of prognostic factors: patient age, type of antecedent pregnancy, interval from gestational event to chemotherapy, hCG concentration, number and site of metastases, largest tumor mass, and previous chemotherapy.
Gestational Trophoblastic Disease.  Introduction/Background Gestational trophoblastic disease (GTD), or abnormal proliferation of placental trophoblastic tissue, is a rare complication of pregnancy. There is considerable variation in the worldwide distribution of GTD, with the highest frequencies reported in Asia and the Middle East and lower rates on the order of 1 per 1,000 pregnancies in Europe and North America [1,2]. Extremes of maternal age and personal history of GTD are known risk factors [1-3]. The American College of Radiology seeks and encourages collaboration with other organizations on the development of the ACR Appropriateness Criteria through society representation on expert panels. Participation by representatives from collaborating societies on the expert panel does not necessarily imply individual or society endorsement of the final document. Reprint requests to: publications@acr.org Gestational Trophoblastic Disease On the whole, women with GTD have a favorable prognosis for cure with early adequate treatment, despite the presence of metastatic disease in some patients. Patients with benign but premalignant lesions are managed with uterine evacuation and enrolled in postoperative hCG surveillance [16]. Hysterectomy in patients not opting to preserve fertility does not eradicate risk of postmolar GTN [16-19]. If malignant GTN other than ETT or PSTT is suspected or has been established, further evaluation for potential metastatic lesions is initiated, clinical risk factors determined, and patients stratified into low- or high-risk groups based on the modified World Health Organization (WHO) prognostic scoring system as adapted by and combined with the international Federation of Gynecology and Obstetrics (FIGO) anatomic staging system [2,20]. This combines anatomic staging with assessment of prognostic factors: patient age, type of antecedent pregnancy, interval from gestational event to chemotherapy, hCG concentration, number and site of metastases, largest tumor mass, and previous chemotherapy.