Casasbuenas Alexandra, Wong Amy E, Sepulveda Waldo
Fetal Medicine Center, Department of Obstetrics and Gynecology, Clinica Las Condes, Santiago, Chile.
J Ultrasound Med. 2008 Mar;27(3):363-9. doi: 10.7863/jum.2008.27.3.363.
The purpose of this study was to investigate the value of first-trimester nuchal translucency (NT) thickness in predicting the pregnancy outcome in monochorionic multiple pregnancies.
Thirty monochorionic multiple pregnancies were evaluated for NT thickness at a median gestational age of 12 weeks (range, 11-14 weeks). Information on pregnancy outcome was obtained from all cases. A poor pregnancy outcome was defined as fetal death or miscarriage before 24 weeks, development of twin-twin transfusion syndrome (TTTS), or preterm delivery before 32 weeks.
The NT thickness was above the 95th percentile for gestational age in at least 1 fetus in 5 (17%) pregnancies, and a poor pregnancy outcome was recorded in 14 (47%) pregnancies. The overall sensitivity was 36% (5/14); specificity, 100% (16/16); positive predictive value, 100% (5/5); and negative predictive value, 64% (16/25). In pregnancies with increased compared with normal NT thickness, no significant correlation was found with the subsequent development of TTTS (1/5 [20%] versus 5/25 [20%]) and miscarriage or fetal death before 24 weeks (1/5 [20%] versus 3/25 [12%]). However, among the 20 pregnancies not complicated by TTTS or loss before 24 weeks, there was a significantly increased rate of delivery before 32 weeks in the former group (3/4 [75%] versus 1/16 [6.3%]; P = .01).
In monochorionic multiple pregnancies, an increased NT thickness measurement had a high specificity and positive predictive value for adverse perinatal outcomes. However, the sensitivity and negative predictive value were low, with a normal NT thickness measurement poorly predicting development of complications; therefore, close sonographic follow-up should be carried out in all cases, irrespective of NT thickness.
本研究旨在探讨孕早期颈部透明带（NT）厚度在预测单绒毛膜多胎妊娠妊娠结局中的价值。
对30例单绒毛膜多胎妊娠进行评估，孕龄中位数为12周（范围11 - 14周）时测量NT厚度。从所有病例中获取妊娠结局信息。不良妊娠结局定义为24周前胎儿死亡或流产、双胎输血综合征（TTTS）的发生或32周前早产。
5例（17%）妊娠中至少有1个胎儿的NT厚度高于孕龄的第95百分位数，14例（47%）妊娠记录有不良妊娠结局。总体敏感性为36%（5/14）；特异性为100%（16/16）；阳性预测值为100%（5/5）；阴性预测值为64%（16/25）。与正常NT厚度相比，NT厚度增加的妊娠中，与随后TTTS的发生（1/5 [20%] 对5/25 [20%]）以及24周前流产或胎儿死亡（1/5 [20%] 对3/25 [12%]）均未发现显著相关性。然而，在20例未合并TTTS或24周前未发生流产的妊娠中，前一组32周前分娩率显著升高（3/4 [75%] 对1/16 [6.3%]；P = 0.01）。
在单绒毛膜多胎妊娠中，NT厚度增加对围产期不良结局具有高特异性和阳性预测值。然而，敏感性和阴性预测值较低，NT厚度正常对并发症发生的预测较差；因此，无论NT厚度如何，所有病例均应进行密切超声随访。
