title: Velamentous cord insertion in monochorionic twins with or without twin-twin transfusion syndrome: Does it matter?
abstract: OBJECTIVE
  To study the association between velamentous cord insertion (VCI) and different outcomes in monochorionic twins with and without twin-twin transfusion syndrome (TTTS).
  
  
  METHODS
  We recorded the cord insertion type in all consecutive monochorionic placentas examined in two tertiary medical centers. The association between VCI and several outcomes was estimated.
  
  
  RESULTS
  A total of 630 monochorionic placentas with TTTS (n = 304) and without TTTS (n = 326) were studied. The incidence of VCI in the TTTS and non-TTTS group was 36.8% and 35.9%, respectively (P = 0.886). The presence of VCI in one twin was significantly associated with small for gestational age (SGA) status (odds ratio [OR] 1.45, 95% CI 1.13, 1.87) and severe birth weight discordance (OR 3.09, 95% CI 1.93, 4.96). Our results also showed significant interaction between TTTS and VCI when we considered intrauterine fetal demise (IUFD) and gestational age (GA) at birth. The prevalence of IUFD in monochorionic pregnancies without TTTS increased from 4.6% to 14.1% in the presence of VCI (P = 0.027). In the TTTS group, the prevalence of IUFD was comparable in the absence or presence of VCI. Similarly, GA at birth was significantly lower in the presence of VCI only in the non-TTTS group.
  
  
  CONCLUSIONS
  Our findings suggest that VCI is not associated with the development of TTTS but increases the risk of adverse outcomes. Both VCI and TTTS independently increase the prevalence of IUFD and lower GA at birth in a similar way, showing that VCI is an important indicator of adverse perinatal outcome in monochorionic twins.
authors.affiliation: Department of Obstetrics and Gynecology, São João Hospital Center, Medical Faculty University of Porto, Porto 4200 - 319, Portugal. Electronic address: teresacostacastro@gmail.com.
authors.forename: T
authors.initials: T
authors.lastname: Costa-Castro
authors.forename: S
authors.initials: S
authors.lastname: De Villiers
authors.forename: N
authors.initials: N
authors.lastname: Montenegro
authors.forename: M
authors.initials: M
authors.lastname: Severo
authors.forename: D
authors.initials: D
authors.lastname: Oepkes
authors.forename: A
authors.initials: A
authors.lastname: Matias
authors.forename: E
authors.initials: E
authors.lastname: Lopriore
mesh_terms: D000046:Academic Medical Centers; D001724:Birth Weight; D005321:Extraembryonic Membranes / Q000473:pathology*; D005260:Female; D005313:Fetal Death / Q000453:epidemiology / Q000209:etiology; D005317:Fetal Growth Retardation / Q000453:epidemiology / Q000209:etiology; D005330:Fetofetal Transfusion / Q000150:complications / Q000473:pathology* / Q000503:physiopathology; D006801:Humans; D015994:Incidence; D007231:Infant, Newborn; D007236:Infant, Small for Gestational Age; D008297:Male; D009426:Netherlands / Q000453:epidemiology; D010920:Placenta / Q000473:pathology*; D010922:Placenta Diseases / Q000453:epidemiology / Q000473:pathology* / Q000503:physiopathology; D011174:Portugal / Q000453:epidemiology; D011247:Pregnancy; D047928:Premature Birth / Q000453:epidemiology / Q000209:etiology; D015995:Prevalence; D012306:Risk; D014430:Twins, Monozygotic; D014470:Umbilical Cord / Q000473:pathology*
keywords: Intrauterine fetal demise; Monochorionic twins; Severe birth weight discordance; Twin–twin transfusion syndrome; Velamentous cord insertion