title: The spherical sac: a suggestive early sign of abdominal pregnancy?
authors.forename: Y T
authors.initials: YT
authors.lastname: Cheung
authors.forename: P C
authors.initials: PC
authors.lastname: Kwok
authors.forename: C
authors.initials: C
authors.lastname: Metreweli
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D011247:Pregnancy; D011269:Pregnancy, Abdominal / Q000175:diagnosis*; D014463:Ultrasonography