A Case of Hook Effect in Molar Pregnancy

Ka Hee Chua, Su Min, Bernard C

Abstract

Molar pregnancies are associated with extremely high levels of BhCG, out of proportion to the stage of pregnancy. However, urine and serum BhCG assays can paradoxically be negative, despite the high BhCG levels, leading to misdiagnosis and delayed treatment. This is due to saturation of the assay by the BhCG molecules. We present such a case where the initial urine pregnancy test was negative in an advanced complete molar pregnancy. Primary care and emergency department physicians should be mindful of this possibility and go on to do serum BhCG with sample dilution in cases where pregnancy is strongly suspected.

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