Heterotopic pregnancy with discordant ultrasonic appearance of fetal cardiac activity

In an interesting experiment of nature, we observed the discordant onset of fetal cardiac activity between the two gestations of a heterotopic pregnancy. After initially detecting cardiac activity only in the tubal gestational sac, we later observed cardiac activity in the intrauterine sac 6 days after laparoscopic salpingectomy. This case illustrates the variable onset of cardiac activity. We advise expectant management of the intrauterine pregnancy in a heterotopic gestation when cardiac activity is not detected initially in the intrauterine sac. (Obstet Gynecol 1992;79:824-5)