RÉSUMÉ
Two hundred and eleven cases of proved hydatidiform mole were included in this study. Sixty two cases of these were successfully selected as early as the first missed period and were followed up for their pregnancy until proved to be definitely cases of hydatidiform mole. For this group ultrasonography was repeated every other day and serum HCG-B was assayed once weekly until definite diagnosis was determined. The present study showed that hydatidiform mole included three definite ultrasonographic entities [the massive vesicular change of the chorion, vesicular mole and molar disease]. Similar differentiation was also encountered and was based on the clinical findings and endocrinal activity in this disease. Ultrasonography is a useful tool diagnosing, classifying and anticipating the course and the prognosis of the hydatidiform mole if done before the 14th week of pregnancy and if follow up by ultrasonography is included. After the 14th week of gestation serial serum HCG-B assay may be a useful tool for classifying and anticipating the course of the disease by considering the percentage and the rate of increase