Problems in the diagnosis of ectopic pregnancy: the pseudogestational sac.

The term pseudogestational sac was first suggested by Mueller in 1979. It was applied to the echo pattern which he noted on ultrasonic examination of 2 patients with ectopic pregnancy. He suggested that the echo pattern, which can easily be misinterpreted as a gestational sac, is produced by the decidual cast with blood contained in its centre. During the past 3 years, 6 cases of pseudogestational sacs have been recorded at K.E.M.H. In 3 of these the possibility of ectopic pregnancy was suggested by the ultrasonologist because of suspicious extra-uterine echo patterns associated with the pseudogestational sac. In the remaining 3 patients the ultrasonologist reported that there was an intrauterine pregnancy, an error which influenced clinical management. These 3 cases are summarized below.