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Updated: May 25, 2026

Accurate and Simple Evaluation of Vascular Anastomoses in Monochorionic Placenta using Colored Dye
Published on: September 5, 2011
Arterio-arterial vascular anastomoses in monochorionic twin placentas with and without twin anemia-polycythemia
S de Villiers1, F Slaghekke, J M Middeldorp
1Division of Neonatology, Department of Pediatrics, J6-S, Leiden University Medical Center, P.O. Box 9600, 2300 RC Leiden, The Netherlands.
Abstract:
We performed a matched case-control study to analyze the placental angioarchitecture, in particular the diameter of arterio-arterial (AA) anastomoses in monochorionic placentas from pregnancies with spontaneous twin anemia-polycythemia sequence (TAPS) compared to a control group of uncomplicated monochorionic placentas. Placental angioarchitecture was analyzed using colored dye injection. AA anastomoses were detected in 20% (3/15) of spontaneous TAPS placentas. The median diameter of AA anastomoses in the group with and without TAPS was 0.4 mm and 2.2 mm, respectively (p = 0.01). In conclusion, AA anastomoses are rarely detected in TAPS placentas. When present, the AA anastomosis is very small, preventing equilibration of hemoglobin levels between both twins.
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