Document Detail


Longitudinal blood flow in shared (arteriovenous anastomoses) and non-shared cotyledons in monochorionic placentae.
MedLine Citation:
PMID:  17081605     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
OBJECTIVES: In this study we aimed to quantitate monochorionic twin placental blood flow in vivo through arterio-venous anastomoses (AVA) and corresponding vessels within normal cotyledons. METHODS: The topography of chorionic plate vasculature was mapped using colour Doppler in ten monochorionic diamniotic twin (MCDA) pregnancies. Cotyledonary flow was derived by insonation of chorionic veins draining normal (n=10) and paired control shared cotyledons (n=10). Venous volume flow was calculated from five determinations of vessel diameter and three of time average mean velocity (TAMV). Measurements were repeated every 2-4 weeks from 18 until 32 weeks' gestation. RESULTS: Blood flow through non-shared and shared cotyledons increased with gestation (p<0.0001). Median flow at 28 weeks through shared cotyledons was 16 ml/min (15-21) (median, interquartile range), lower than in shared cotyledons (31, 25-35) (p<0.001), as was median volume flow across gestation calculated as area under the curve (shared cotyledons 126 (122-167), control cotyledons 269 (214-274), p=0.01). However, velocity was similar, with the difference due to smaller vein diameters draining shared compared to normal cotyledons (mean 3.6mm (SD 0.8) vs. 4.5mm (0.8), p=0.004). Ex vivo quantitation of insonated cotyledons and of all cotyledons confirmed the difference in vein diameter in the placentae studied. CONCLUSIONS: Blood flow through shared cotyledons was lower across gestation than through paired normal cotyledons in the placenta studied due to the smaller diameter of the AVA vessels. The size of AVAs rather than simply their presence and direction may contribute to determining transfusional imbalance in monochorionic twins.
Authors:
L Y Wee; M Sullivan; K Humphries; N M Fisk
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2006-10-31
Journal Detail:
Title:  Placenta     Volume:  28     ISSN:  0143-4004     ISO Abbreviation:  Placenta     Publication Date:    2007 May-Jun
Date Detail:
Created Date:  2007-04-24     Completed Date:  2007-08-01     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  8006349     Medline TA:  Placenta     Country:  England    
Other Details:
Languages:  eng     Pagination:  516-22     Citation Subset:  IM    
Affiliation:
Experimental Fetal Medicine Group, Institute of Reproductive and Developmental Biology, Imperial College London, Hammersmith Campus, London, UK. ling.wee@uclh.org <ling.wee@uclh.org>
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MeSH Terms
Descriptor/Qualifier:
Arteriovenous Anastomosis / physiology*
Blood Flow Velocity*
Chorion / blood supply,  physiology
Cotyledon / physiology*
Female
Fetal Development
Gestational Age
Humans
Placenta / blood supply*
Pregnancy
Ultrasonography, Prenatal

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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