title: Angioarchitecture of monochorionic placentas in relation to the twin-twin transfusion syndrome.
abstract: OBJECTIVE
  Twin-twin transfusion syndrome in the midtrimester is associated with a perinatal mortality rate exceeding 80%. Although attributed to intertwin transfusion along vascular anastomoses, these occur in all monochorial placentas, not just the 10% with twin-twin transfusion syndrome. We compared fetoplacental angioarchitecture in monochorionic twin placentas with and without twin-twin transfusion syndrome.
  
  
  METHODS
  The fetoplacental circulations of both twins in 20 monochorial placentas were perfused immediately after delivery under optimal physiologic conditions and anastomoses delineated by dye-contrast injection. Ten were from pregnancies with evidence of midtrimester twin-twin transfusion syndrome and 10 were from pregnancies without twin-twin transfusion syndrome.
  
  
  RESULTS
  Placentas from pregnancies with twin-twin transfusion syndrome had significantly fewer anastomoses than did those without twin-twin transfusion syndrome, both overall (median one versus six, respectively; p < 0.001) and for each of the different types (arterioarterial, venovenous, and arteriovenous, p < 0.001). Whereas multiple anastomoses were present in all controls, only one twin-twin transfusion syndrome placenta had more than a single communication. Anastomoses in the twin-twin transfusion syndrome group were more likely to be of the deep than the superficial type (80% vs 36% in controls, p < 0.01).
  
  
  CONCLUSIONS
  Placental vascular anastomoses in monochorial pregnancies complicated by twin-twin transfusion syndrome are both fewer in number and of a different type than those without twin-twin transfusion syndrome. These differences seem implicated in the underlying pathophysiologic features of twin-twin transfusion syndrome and are of relevance to the development of newer therapies such as placental laser surgery.
authors.affiliation: Institute of Obstetrics and Gynaecology, Royal Postgraduate Medical School, Queen Charlotte's and Chelsea Hospital, London, United Kingdom.
authors.forename: R
authors.initials: R
authors.lastname: Bajoria
authors.forename: J
authors.initials: J
authors.lastname: Wigglesworth
authors.forename: N M
authors.initials: NM
authors.lastname: Fisk
mesh_terms: D001159:Arterio-Arterial Fistula; D001164:Arteriovenous Fistula; D001165:Arteriovenous Malformations; D016022:Case-Control Studies; D005260:Female; D005330:Fetofetal Transfusion / Q000473:pathology*; D006801:Humans; D010920:Placenta / Q000098:blood supply* / Q000473:pathology; D011247:Pregnancy; D011262:Pregnancy Trimester, Second; D011272:Pregnancy, Multiple; D014430:Twins, Monozygotic