Different placentation patterns in viable compared with nonviable tubal pregnancy suggest a divergent clinical management

OBJECTIVE: In contrast to tubal abortions, viable ectopic pregnancies in co lor Doppler ultrasonography exhibit a signal-intensive ring around the gest ational sac. We investigated the underlying differences in implantation and placentation. STUDY DESIGN: Histologic sections of fallopian tubes carrying viable tubal pregnancies (13 patients) and tubal pregnancies that aborted (8 patients) w ere immunostained for cytokeratin, MIB-1, CD-34, and CD-68. The data were s tudied by computer-aided image analysis followed by statistical evaluation (Student t test, P <.05). RESULTS: In contrast to tubal abortions, viable tubal pregnancies are chara cterized by implantation at the mesosalpingial rather than at the antimesos alpingial side of the organ. They exhibit deeper trophoblast invasion into the thickened tubal wall, more intense trophoblast proliferation (P <.001), and increased villous vascularization(P<.001). CONCLUSION: The morphologic findings correlate with preoperative Doppler ul trasonography. They suggest that trophoblast invasion, placental growth, an d the fate of tubal pregnancies depend on the implantation site. They encou rage a conservative management of anti-mesosalpingially implanted, nonviabl e ectopic pregnancies in clinically stable patients.