A phantom human chorionic gonadotropin in the case of molar pregnancy.

Accurately interpreting persistent, low human chorionic gonadotropin (hCG) levels is essential for managing gestational trophoblastic disease. Erroneous interpretation can lead to inappropriate interventions, including unnecessary chemotherapy or hysterectomy, or unjustified changes in chemotherapeutic regimens due to misidentification of a false-positive hCG as a true positive. The predominant etiology of phantom hCG is the presence of heterophilic antibodies. Consequently, screening for urine hCG is indispensable for its diagnosis because immunoglobulin is not generally present in urine. Here, we report about phantom hCG after a complete hydatidiform mole. Initial urine hCG evaluations were negative, although the serum hCG levels remained positive, leading to the diagnosis of phantom hCG. After subsequent delivery, urine hCG levels persisted at diminished levels. However, a different assay yielded negative hCG results for both serum and urine samples. The patient subsequently gave birth. The absence of hCG was consistently confirmed over five years.