First trimester uterine rupture and scar pregnancy

Uterine rupture during the first trimester of pregnancy is an extremely rare, but life-threatening cause of intraperitoneal hemorrhage. Up to the knowledge of the authors all reports of first trimester uterine ruptures are related to scar dehiscences following previous cesarean sections or occurred in unscarred uteri of multiparous women. In cases of multiparity silent ruptures cannot be precluded, so that the uterus might be scarred during the following pregnancy. In early pregnancy of approximately 4-5 weeks, vaginal ultrasonography may clearly verify a scar pregnancy, but sonographical diagnostic findings may change with the pregnancy progress. In all cases of reported first trimester ruptures in pregnancies with previous cesarean sections or in pregnancies of multiparous women reported in literature, dating scans were performed too late for to preclude pregnancies in the scar. We postulate our hypotheses, that all first trimester uterine ruptures are caused by scar implantation of the trophoblast.