Molar pregnancy is characterized by high level of serum b hcg which can be usually detected by urine pregnancy test as a first screening test. Urine pregnancy test is also used as the first screening test for patients of reproductive age presenting with gynecological problem in order to exclude pregnancy. Rarely large amounts of b human chorionic gonadotrophin (hcg) may cause a false negative result due to over saturation of the assay system, known as, ‘the hook effect’. This can result clinical dilemma in the diagnosis and delay in the management. When there is clinical features of molar pregnancy, the knowledge of “The Hook Effect” will help at arriving at the diagnosis.
β hCG(serum β -human chorionic gonadotropin, Hook effect, Molar pregnancy, Urine pregnancy test.