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

BACKGROUND

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.

CASES: 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).

CONCLUSION

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.