Intrauterine shelves in pregnancy: sonographic observations.

Twenty-five shelves of tissue, all having a free edge within the uterine cavity, were identified by sonography in 24 singleton pregnancies. In no case did the shelf attach to the fetus or restrict fetal motion. The fetus was sonographically normal in 23 pregnancies, and no fetus developed amniotic-band syndrome. One fetus had anencephaly, probably unrelated to amniotic-band syndrome. Although these shelves may be due to synechiae, only eight (32%) of the patients had a history of dilatation and curettage or cesarean delivery, which predispose the patient to formation of synechiae. This experience suggests that when a shelf of tissue with a free edge is present within the pregnant uterus, there should be no concern for the development of amniotic-band syndrome as long as a complete sonographic survey of the fetus reveals no abnormalities.