Recognising gestational trophoblastic disease

Abstract

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.