Syncytiotrophoblastic fragments in first-trimester decidual veins: Evidence of placental perfusion by the maternal circulation early in pregnancy

OBJECTIVE: To determine whether maternal placental perfusion occurs in the first trimester, this study compared veins in endometrium with those in dec idua. We hypothesize that veins draining the placenta become dilated and co ntain syncytiotrophoblastic fragments. STUDY DESIGN: Normal late-secretory endometrial biopsy specimens (n = 10) w ere compared with elective abortion decidua at 7 to 11 weeks (n = 100). Tis sue sections were processed by routine staining and immunohistochemical stu dies. The cross sections of veins and glands were counted in 25 decidual bi opsy specimens, and the number of syncytiotrophoblastic fragments in veins or glands was determined. Statistical significance by chi(2) or linear regr ession analysis was P < .05. RESULTS: All sets of decidua had dilated veins; no secretory endometrium di d. Intravenous syncytiotrophoblastic fragments were seen in 91 of 100 sets of decidua. There were more syncytial elements in veins (572/6845, 8.4%) th an in glands (13/23,310, 0.06%) (P < .001). CONCLUSION: Decidual veins were distended and contained syncytiotrophoblast ic fragments, consistent with maternal intervillous perfusion in the first trimester.