"Hook effect" in complete hydatidiform molar pregnancy: a falsely low level of beta-HCG.

Abstract

In some cases of gestational trophoblastic disease, a large amount of serum beta-hCG may lead to the high-dose "hook effect" with falsely low serum levels, creating misdiagnosis or delay in diagnosis and therapeutic hazards to the patient. In two cases of the hook effect in complete hydatidiform mole, ultrasonographic scan showed intrauterine echogenic material, whereas diluted serum specimens gave very high levels of beta-hCG (1,600,000 and 2,225,000 mIU/mL). The possibility of a method-dependent hook effect must be considered. Early recognition of falsely low values of beta-hCG can allow correction to the true values by various methods, such as serum dilution before the radioimmunometric method.