Lewi Liesbeth, Cannie Mieke, Blickstein Isaac, Jani Jacques, Huber Agnes, Hecher Kurt, Dymarkowski Steven, Gratacós Eduard, Lewi Paul, Deprest Jan
Department of Obstetrics and Gynecology, University Hospital, Leuven, Belgium.
Am J Obstet Gynecol. 2007 Dec;197(6):587.e1-8. doi: 10.1016/j.ajog.2007.05.009.
The purpose of this study was to examine the relationship between placental territory and birthweight discordance and vascular anastomoses in monochorionic diamniotic twin placentas from pregnancies that were not complicated by twin-to-twin transfusion syndrome with 2 liveborn twins.
Placentas originated from a prospective follow-up study of monochorionic diamniotic twins included in the first trimester. After injection with dyed barium sulphate, a digital x-ray angiography and high-resolution digital photograph were taken. The 2 venous territories were delineated on the angiogram. The diameter of each arterioarterial anastomosis and of each vein that participated in an arteriovenous anastomosis was measured on the digital photograph. Net transfusion over the arteriovenous anastomoses was calculated as the difference between the total venous diameters of the 2 placental parts.
One hundred placentas were analyzed. Birthweight discordance increased with placental territory discordance (P < .0001). Arterioarterial diameter (P < .01), net arteriovenous transfusion (P < .001), and total anastomotic diameter (P < .01) increased with placental territory discordance. On the other hand, birthweight discordance for a given placental territory discordance decreased with increasing arterioarterial diameter (P < .01), net arteriovenous transfusion (P < .001), and total anastomotic diameter (P < .01).
In unequally shared placentas, the 2 fetal circulations are more tightly linked than in equally shared placentas, which may reduce the birthweight discordance for a given placental territory discordance.
本研究旨在探讨在未并发双胎输血综合征且双胎均存活的单绒毛膜双羊膜囊双胎妊娠中，胎盘面积差异与出生体重不一致及血管吻合之间的关系。
胎盘源自一项对孕早期纳入的单绒毛膜双羊膜囊双胎的前瞻性随访研究。注入硫酸钡造影剂后，进行数字X线血管造影和高分辨率数字摄影。在血管造影图上描绘出两个静脉区域。在数字照片上测量每个动脉 - 动脉吻合口以及参与动静脉吻合的每条静脉的直径。通过计算两个胎盘部分的总静脉直径之差来得出动静脉吻合处的净输血量。
共分析了100个胎盘。出生体重不一致程度随胎盘面积不一致程度增加（P <.0001）。动脉 - 动脉直径（P <.01）、动静脉净输血量（P <.001）和总吻合口直径（P <.01）随胎盘面积不一致程度增加。另一方面，对于给定的胎盘面积不一致程度，出生体重不一致程度随动脉 - 动脉直径增加（P <.01）、动静脉净输血量增加（P <.001）和总吻合口直径增加（P <.01）而降低。
在胎盘面积分配不均的情况下，两个胎儿循环之间的联系比胎盘面积分配均匀时更为紧密，这可能会降低在给定胎盘面积不一致程度时的出生体重不一致程度。
