Negative βhCG and Molar Pregnancy: The Hook Effect

• Autor(a) principal: Lobo Antunes, Isabel
• Data de Publicação: 2017
• Outros Autores: Curado, Joana, Quintas, Ana, Pereira, Alcides
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: https://www.actamedicaportuguesa.com/revista/index.php/amp/article/view/8603
• topic: Chorionic Gonadotropin; beta Subunit; Human; Hydatidiform mole; Gonadotropina Coriónica Humana Subunidade beta; Mola Hidatiforme

Molar pregnancy, included in gestational trophoblastic disease, is a benign pathology with ability to metastasize, usually occurring with excessively high βhCG levels. Clinical scenario is usually a woman in extremes of reproductive age presenting with amenorrhoea, pain and vaginal blood loss; signs derived from high βhCG levels may be present (hyperthyroidism, hyperemesis). Diagnosis is based on a positive pregnancy test – usually a qualitative urinary test. The limitation of this test results from its inability to become positive in presence of markedly high levels of βhCG, saturating the antigens used – known as the ‘hook effect’. With the widespread use of gynaecological ultrasound cases of molar pregnancy have been diagnosed in timely fashion. We describe a case referred as a degenerating fibroid, with a negative urinary pregnancy test. Transvaginal ultrasound was highly suggestive of molar pregnancy, which was confirmed with a quantitative βhCG test, allowing for timely treatment. The importance of a high index of suspicion for this pathology is tremendous to avoid the devastating consequences of a delayed diagnosis.