twin molar pregnancy
A term of art for the über rare (1-5/105 pregnancies) coexistence of a normal intrauterine pregnancy (usually a single, non-twin fetus) and gestational trophoblastic disease–GTD, one or moles together, which typically occurs in a background of infertility treatment and in vitro fertilisation.
Ultrasound image of complete hydatidiform mole with coexisting fetus and placenta (from Shazly et al). Because management is problematic, twin molar pregnancies should be handled in tertiary care centres, especially if the woman elects to carry the normal “twin” to term.
Synonym Twin pregnancy
References Shazly et al. Journal of Medical Case Reports 2012 6:95 doi:10.1186/1752-1947-6-95