title: The decidual cast of ectopic pregnancy: a confusing ultrasonographic appearance.
abstract: The appearance of the central uterine cavity was analyzed in 39 cases of ectopic pregnancy. In nearly 20% of cases, a fluid collection surrounded by an echogenic ring was present which could be mistaken for a normal early intrauterine pregnancy. When ectopic pregnancy is suspected clinically, and there is fluid in the cul-de-sac or an adnexal mass on ultrasound, a fetal pole should be evident within the central fluid collection before a definitive diagnosis of intrauterine pregnancy is made.
mesh_terms: D003656:Decidua; D004717:Endometrium; D005260:Female; D006801:Humans; D011247:Pregnancy; D011271:Pregnancy, Ectopic / Q000175:diagnosis*; D014463:Ultrasonography