Objective: To investigate the clinical outcome and placental characteristics of spontaneous twin anemia-polycythemia sequence (sTAPS). Methods: Twelve cases with sTAPS delivered in Peking University Third Hospital from May 2013 to August 2016. The data of ultrasound characteristics, gestational age at delivery, and 1 minute Apgar score were analyzed, retrospectively. Placental superficial vascular anastomoses, placental territory discordance and the ratio of umbilical cords insertion distance to the longest placental diameter were also analyzed. Results: (1) Only 1 case of sTAPS was diagnosed prenatally, the others were diagnosed postnatally because the fetal middle cerebral artery(MCA) doppler was not measured regularly. Five cases were complicated with selective intrauterine growth restriction (sIUGR). The median gestational age at delivery was 32.8 weeks (31-37 weeks) . The pregnancies were terminated because 3 cases were sIUGR type Ⅰ, 1 case was sIUGR type Ⅱ, 1 case was sIUGR type Ⅲ, 2 cases were fetal distress, 2 cases were severe pre-eclampsia, 2 cases were premature rupture of membrane, 1 case was fetal hydrops with abnormal doppler waveforms of ductus venouses. (2) When 5 sIUGR cases were excluded, there was no difference between the twins in birth weight [1 797 g (940-2 620 g) , 1 648 g (980-2 500 g) ; P=0.688]. The hemoglobin (Hb) level in all donor was significantly lower than recipient (P=0.000) and the inter-twin Hb difference was 147.6 g/L (84.0-216.0 g/L). While the reticulocyte percentage in donor was significantly higher than recipient (P=0.013) and reticulocyte percentage ratio was 3.60 (1.04-7.50). Five donor newborns had neonatal asphyxia, including 1 severe asphyxia, while no asphyxia happened in the recipient twins. (3) Arterio-arterial (A-A) anastomoses, veno-venous (V-V) anastomoses, arterio-venous (A-V) anastomoses were found in 3, 1 and 11 placentas, respectively. The total number of anastomoses was 2 (1-5) and the total diameter was 1.1 mm (0.4-2.1 mm), including 0 (0-1) A-A anastomoses with 0.2 mm (0.0-0.9 mm) in diameter and 2 (0-5) A-V anastomoses with 0.7 mm (0.0-2.1 mm) in diameter. The placental territory discordance was 0.17 (0.02-0.40) and the ratio of umbilical cords insertion to the longest placental diameter was 0.82 (0.34-0.99). Conclusions: The pathogenesis of sTAPS might result from slow and chronic blood transfusion from donor to recipient through a few minuscule vascular anastomoses in the placenta. In all monochorionic twins, especially sIUGR cases, MCA doppler should be monitored closely in the second and third trimester, in order to diagnose and manage sTAPS in time.
目的： 总结自发性双胎贫血-红细胞增多序列征（sTAPS）孕妇的妊娠结局，并通过对分娩后胎盘进行浅表血管灌注探讨其胎盘形态的特点。 方法： 收集2013年5月至2016年8月于北京大学第三医院诊断为sTAPS孕妇共12例，回顾性分析其孕期超声检查特点、分娩孕周，新生儿1分钟Apgar评分、血红蛋白水平及网织红细胞百分比等；对分娩后胎盘进行浅表血管灌注，分别测量两个胎儿间胎盘浅表吻合血管的类型、数量及直径，计算两个胎儿胎盘面积差值比，并计算两根脐带插入点距离与胎盘最长径的比值。 结果： （1）一般资料：12例sTAPS孕妇中，仅1例孕期规律监测大脑中动脉血流，在产前诊断为sTAPS；其余11例均在产后诊断为sTAPS，其中5例孕期诊断为选择性胎儿生长受限（sIUGR），6例未发现异常。12例sTAPS孕妇的中位分娩孕周为32.8周（范围：31~37周）。终止妊娠的指征分别为：sIUGR Ⅰ型3例，sIUGRⅡ型1例，sIUGR Ⅲ型1例，胎儿窘迫2例，重度子痫前期2例，胎膜早破2例，胎儿水肿及静脉导管血流异常1例。（2）围产儿结局：除5例sIUGR患儿外，其余7例受血儿的新生儿出生体质量与供血儿比较，差异无统计学意义[分别为1 797 g（940~2 620 g）、1 648 g（650~2 500 g），P=0.688]。12例供血儿的新生儿血红蛋白水平明显低于受血儿[分别为85.0 g/L（41.0~130.0 g/L）、232.6 g/L（198.0~267.0 g/L），P=0.000]，供血儿与受血儿的血红蛋白水平相差147.6 g/L（84.0~226.0 g/L）；供血儿的新生儿网织红细胞百分比明显高于受血儿[分别为21.03%（6.41%~62.99%）、5.58%（2.59%~8.41%），P=0.013]，供血儿与受血儿的网织红细胞百分比的比值为3.60（1.04~7.49）；12例供血儿中5例发生新生儿轻度窒息，1例重度窒息，受血儿无新生儿窒息发生。（3）胎盘形态特点：分娩后胎盘浅表血管灌注显示，12份胎盘中，1份存在静脉-静脉（V-V）吻合血管；其余11份均存在动脉-静脉（A-V）吻合血管，且3份同时存在动脉-动脉吻合（A-A）吻合血管。胎盘中吻合血管的中位条数、直径总和分别为2条（1~5条）、1.1 mm（0.4~2.1 mm）；其中A-A吻合血管的中位数、直径总和分别为0条（0~1条）、0.2 mm（0.0~0.9 mm），A-V吻合血管中位数、直径总和分别为2条（0~5条）、0.7 mm（0.0~2.1 mm）。两个胎儿胎盘面积差值比为0.17（0.02~0.40），两根脐带于胎盘插入点距离与胎盘最长径的中位比值为0.82（0.34~0.99）。 结论： 单绒毛膜双胎胎盘浅表吻合血管少且细导致的双胎之间慢性输血可能是发生sTAPS的原因。在孕中、晚期严密监测胎儿大脑中动脉血流有助于在孕期及时诊断和处理sTAPS。.
Keywords: Anemia; Diseases in twins; Placenta; Polycythemia; Pregnancy outcome.