Ultrasonic patterns in trophoblastic disease

Gestatational trophoblastic disease: multimodality imaging assessment with special emphasis on spectrum of abnormalities and value of imaging in staging and management of disease

Gestational trophoblastic disease is a spectrum of disorders of varying malignant potential arising from trophoblastic cells and encompassing hydatidiform moles and persistent trophoblastic neoplasia. Ultrasound is the initial imaging investigation of choice when gestational trophoblastic disease is suspected. Complete hydatiform mole, the most common form of molar pregnancy, usually has a characteristic "cluster of grapes" appearance, especially on second-trimester ultrasounds. Persistent trophobastic neoplasia usually appears as a focal, hypervascular myometrial mass on pelvic ultrasound. Pelvic magnetic resonance imaging is often used as a problem-solving tool in equivocal or complicated cases of gestational trophoblastic disease to assess the degree of invasion into the myometrium and surrounding tissues. Chest x-ray, brain magnetic resonance imaging, and body computed tomography scans are primarily used for the evaluation of metastatic disease, which usually occurs in the context of choriocarcinomas. Choriocarcinoma metastases are usually hypervascular and have a tendency to bleed, features that are reflected in their imaging appearance.

Recognising gestational trophoblastic disease

Gestational trophoblastic disease (GTD) is a group of interrelated tumours originating from the placenta. Hydatidiform molar (HM) pregnancy is the most common form of GTD; this includes both partial hydatidiform molar (PHM) and complete hydatidiform molar (CHM) pregnancies. The importance of such a condition derives from its potential for persistent trophoblastic disease; this is noted to be more common after a CHM (10-20%) compared to a PHM (0.1-11%). The recent routine use of high-resolution trans-vaginal ultrasound (TVS) in early pregnancy has improved the recognition and thus pre-surgical diagnosis of molar pregnancy. Pre-surgical recognition aids planning of surgery, decreases intra-operative complications and identifies women with potential persistent trophoblastic disease. Despite the introduction of TVS, its performance in preoperative diagnosis is quite poor. This is primarily because of the histomorphometric features of the hydropic villi. A significant proportion of HM cases demonstrates minimal hydropic change in the first trimester and therefore is likely to remain unidentifiable by ultrasound examination prior to surgical evacuation, even with improved sonographer expertise. The overall sensitivity for the ultrasound diagnosis of HM is 50-86%. Ultrasound diagnosis of CHM can be made in approximately 80% of the cases, whilst ultrasound diagnosis of PHM is less accurate and nearly 70% of cases will be missed. Correlation of the ultrasonographic findings with human chorionic gonadotropin levels can further improve the recognition of HM pregnancy pre-surgery. Although ultrasound can be helpful in the diagnosis of molar pregnancies, histological confirmation is mandatory. Histological confirmation post-curettage is still the gold standard for the diagnosis of GTD. In this article, we critically evaluate the role of TVS in the pre-surgical recognition of GTD.