title: Identification of arterio-venous anastomoses in vivo in monochorionic twin pregnancies: preliminary report.
abstract: OBJECTIVE
  To determine whether it is possible to identify in vivo placental arterio-venous anastomoses (AVAs) by color Doppler flow mapping.
  
  
  METHODS
  Three monochorionic twin pregnancies (one with and two without twin-to-twin transfusion syndrome) underwent placental mapping by color Doppler ultrasound. Placental vessels along the chorionic plate were recorded together with the direction of blood flow and their location in relation to the cord insertions and to superficial arterio-arterial anastomoses. Suggestive AVAs were mapped topographically and results were compared with the findings of formal postnatal placental injection studies.
  
  
  RESULTS
  An AVA was identified in each of the three cases. Injection studies showed multiple AVAs. Each antenatally identified AVA was confirmed at placental injection study. Their placental location correlated to other landmarks as predicted by ultrasound.
  
  
  CONCLUSIONS
  This preliminary report demonstrates that AVAs can be identified using color Doppler ultrasound. This may facilitate planning for highly selective ablation of AVAs, and shorter procedure times. Formal studies are now indicated to determine the accuracy of this technique.
authors.affiliation: Centre for Fetal Care, Department of Materno-Fetal Medicine, Imperial College School of Medicine, Queen Charlotte's & Chelsea Hospital, Goldhawk Rd,  London, W6 OXG, UK.
authors.forename: M J
authors.initials: MJ
authors.lastname: Taylor
authors.forename: D
authors.initials: D
authors.lastname: Farquharson
authors.forename: P M
authors.initials: PM
authors.lastname: Cox
authors.forename: N M
authors.initials: NM
authors.lastname: Fisk
mesh_terms: D001163:Arteriovenous Anastomosis / Q000000981:diagnostic imaging*; D002823:Chorion / Q000000981:diagnostic imaging; D005260:Female; D006801:Humans; D011247:Pregnancy; D014430:Twins, Monozygotic; D018615:Ultrasonography, Doppler, Color; D016216:Ultrasonography, Prenatal