title: Early intrauterine pregnancy or decidual cast: an anatomic--sonographic approach.
abstract: In order to differentiate an early intrauterine gestation from an ectopic pregnancy with decidual cast, demonstration of the uterine cavity as a structure distinct from the gestational sac is suggested. Anatomically, normal implantation occurs separately from the endometrial canal, whereas decidual casts form within the canal. Using real-time sonography, physician observers were able to demonstrate two separate structures in 79 per cent of normal pregnancies of eight weeks' gestation or less when a special effort was made; routine longitudinal and transverse static and real-time scans were less helpful.
mesh_terms: D003656:Decidua / Q000473:pathology*; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D011271:Pregnancy, Ectopic / Q000175:diagnosis*; D014463:Ultrasonography; D014599:Uterus / Q000033:anatomy & histology