New criteria for the diagnosis of gestational trophoblastic disease.

The purpose of the study was to test the hypothesis of whether the combined use of ultrasound and human chorionic gonadotropin (hCG) determinations could increase the diagnostic accuracy of sonography in the diagnosis of hydatidiform mole. The criteria used were the absence of fetal heart movement by ultrasound when the hCG level was above 82,350 mIU/mL and the presence of an hCG level in excess of 2 SD above the mean for the biometrically derived gestational age for suspected partial moles. The threshold of 82,350 mIU/mL was derived by probit analysis of the hCG serum levels of a population of normal intrauterine pregnancies prospectively examined to determine the level of hCG at which fetal heart activity would be visible by sonography. The diagnostic accuracy of these criteria was compared with the preoperative sonographic examination in 36 hydatidiform moles. When sonography was used alone, 15 of 36 cases (41.6%) did not have a definitive diagnosis on the first examination. The combination of hCG and ultrasound would have correctly identified 32 of the 36 cases (88.8%). This improvement was statistically significant (P less than .005).