[Problem in echographic diagnosis: intrauterine pseudo-sac].

The authors report eight cases of an intra-uterine pseudo-sac giving a wrong diagnosis of intra-uterine pregnancy. In two cases there was hypertrophy of the uterine mucosa and in six cases there was decidual change. The pseudo-sac corresponds to: either a blood clot held by the uterine mucosa; or a marked hypertrophy of the endometrium with intense decidualization and massive oedema. Certain characteristic criteria suggest that a pseudo-sac may be in the uterus; the oblong shape, dimensions which do not accord with the period of amenorrhoea, absence of peripheral and linear thickening, the variety of sites in which the picture is seen and in particular its disappearance, which makes it difficult to localise it in all sections. On the other hand it is not possible to diagnose between an intra-uterine pseudo-gestational sac and an early intra-uterine pregnancy which is not growing, in our present state of knowledge.