title: Nuchal translucency thickness in monochorionic multiple pregnancies: value in predicting pregnancy outcome.
abstract: OBJECTIVE
  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.
  
  
  METHODS
  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.
  
  
  RESULTS
  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).
  
  
  CONCLUSIONS
  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.
authors.affiliation: Fetal Medicine Center, Department of Obstetrics and Gynecology, Clinica Las Condes, Santiago, Chile.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Casasbuenas
authors.forename: Amy E
authors.initials: AE
authors.lastname: Wong
authors.forename: Waldo
authors.initials: W
authors.lastname: Sepulveda
mesh_terms: D000328:Adult; D002823:Chorion; D005260:Female; D005313:Fetal Death / Q000000981:diagnostic imaging; D005330:Fetofetal Transfusion / Q000000981:diagnostic imaging; D006801:Humans; D048208:Nuchal Translucency Measurement / Q000379:methods*; D011237:Predictive Value of Tests; D011247:Pregnancy; D011256:Pregnancy Outcome; D011261:Pregnancy Trimester, First; D018570:Risk Assessment / Q000379:methods; D012680:Sensitivity and Specificity; D014430:Twins, Monozygotic