Wee L Y, Taylor M, Watkins N, Franke V, Parker K, Fisk N M
Centre for Fetal Care, Queen Charlotte's & Chelsea Hospital, United Kingdom.
Placenta. 2005 Jan;26(1):19-24. doi: 10.1016/j.placenta.2004.04.007.
To characterise arterio-venous anastomoses (AVA) in monochorionic (MC) placentae and determine (i) whether shared cotyledons lie beneath the co-termination of an artery from one twin and a vein to the contralateral twin and (ii) whether all AVA can be detected by visual inspection of the chorionic plate.
Vascular casts were made of 15 MC placentae. The number of typical AVAs suspected visually before digestion was compared with the number of AVAs identified after acid digestion.
Thirty-three of 67 (49%) suspected typical AVAs were confirmed as typical after casting. There were five false positives and no false negatives. The remainder were classified as atypical AVAs, found in > or =90% of MC placentae. Type I (small vascular connections between two apparently normal cotyledons not seen before casting) and Type II (shared cotyledons arising within larger apparently normal cotyledons) atypical AVAs were found in 53% and 73% of placentae, respectively.
Only half the shared cotyledons in MC placentae are characterised by co-termination of an artery and vein on the chorionic plate. We report the existence of deep anastomoses beneath the chorionic plate that cannot be visualised by chorionic plate inspection. These findings have implications for laser treatment of twin-twin transfusion syndrome.
描述单绒毛膜（MC）胎盘的动静脉吻合（AVA）情况，并确定（i）共享叶是否位于一个胎儿的动脉与对侧胎儿的静脉共同终止处下方，以及（ii）是否通过观察绒毛膜板就能检测到所有的AVA。
对15个MC胎盘制作血管铸型。将消化前肉眼疑似的典型AVA数量与酸消化后确定的AVA数量进行比较。
67个疑似典型AVA中，有33个（49%）在铸型后被确认为典型。有5例假阳性，无假阴性。其余的被归类为非典型AVA，在≥90%的MC胎盘中发现。I型（铸型前未见的两个明显正常叶之间的小血管连接）和II型（在较大的明显正常叶内出现的共享叶）非典型AVA分别在53%和73%的胎盘中发现。
MC胎盘中只有一半的共享叶具有绒毛膜板上动脉和静脉共同终止的特征。我们报告了绒毛膜板下方存在无法通过绒毛膜板检查看到的深部吻合。这些发现对双胎输血综合征的激光治疗有影响。
