The ratio of placental territory discordance to birthweight discordance was calculated in monochorionic diamniotic twin placentas. We then determined whether the ratio: (1) correlated with the overall diameter of the placental superficial vascular anastomoses and (2) was different in normal monochorionic diamniotic twin (normal MCDA), twin-to-twin transfusion syndrome (TTTS), and selective intrauterine growth restriction (sIUGR) pregnancies. A prospective study of MCDA placentas was conducted from April 1, 2016, to April 1, 2019, including three groups, normal MCDA (N = 49), TTTS (N = 38), and sIUGR (N = 52). Placentas were studied via dye injection. In the normal MCDA, sIUGR, and TTTS groups, the ratio positively correlated with the overall diameter of the placental superficial vascular anastomoses (Spearman’s = 0.295, 0.619, and 0.530; p = 0.040, <0.001, and 0.001, respectively) and gradually decreased from normal MCDA to sIUGR and to TTTS (2.88 (0.34, 64.25), 1.70 (0.27, 4.52), and 1.03 (0.12, 15.17); p < 0.001, p = 0.016/<0.001/0.005, respectively). The placental territory discordance to birthweight discordance ratio is an effective index reflecting the overall vascular anastomoses in MCDA placentas.

计算单绒毛膜双羊膜双胎胎盘中胎盘区域不一致与出生体重不一致的比率。然后，我们确定该比率是否：（1）与胎盘浅表血管吻合的总直径相关，以及（2）在正常单绒毛膜双羊膜双胞胎（正常 MCDA）、双胎输血综合征（TTTS）和选择性双胎中是否不同。宫内生长受限（sIUGR）妊娠。2016年4月1日至2019年4月1日进行了MCDA胎盘的前瞻性研究，包括三组：正常MCDA（N  = 49）、TTTS（N  = 38）和sIUGR（N  = 52）。通过染料注射研究胎盘。在正常MCDA、sIUGR和TTTS组中，该比率与胎盘浅表血管吻合口的总直径呈正相关（Spearman = 0.295、0.619和0.530；p = 0.040、<0.001和0.001，分别）并逐渐 下降从正常 MCDA 到 sIUGR 和 TTTS（分别为 2.88 (0.34, 64.25)、1.70 (0.27, 4.52) 和 1.03 (0.12, 15.17)；p < 0.001，p = 0.016/<0.001 /  0.005 ）  。胎盘区域不一致性与出生体重不一致性比是反映MCDA胎盘整体血管吻合情况的有效指标。