Document Detail

How repeat measurements affect the mean diameter of the umbilical vein and the ductus venosus.
MedLine Citation:
PMID:  9674089     Owner:  NLM     Status:  MEDLINE    
Blood flow measurement in the fetus is susceptible to substantial error. Increased numbers of measurements can improve the precision. To quantify this, we assessed how the number of ultrasound measurements affected the calculation of individual mean diameters of fetal veins. A study of the umbilical vein (UV) and ductus venosus (DV) was carried out in 167 pregnancies in a clinical setting. The UV diameter was measured 2-13 times in 163 participants and the DV for the same number of times in 158. A one-way analysis of variance gave mean within-subject SD of 0.23 mm for the UV (diameter 2.0-8.0 mm) and 0.17 mm for the DV (diameter 0.3-2.3 mm). The 95% limit for the within-subject mean diameter calculated from two, four, six and ten measurements of the UV were 0.31, 0.22, 0.18 and 0.14 mm, respectively. For the DV the corresponding results were 0.23, 0.16, 0.13 and 0.10 mm. The study shows how increasing the number of measurements to calculate a mean diameter substantially improves the precision of vascular cross-section assessment. The limitation of the method is expressed in the exponential increase in numbers needed to achieve further improvement.
T Kiserud; S Rasmussen
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Publication Detail:
Type:  Clinical Trial; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Ultrasound in obstetrics & gynecology : the official journal of the International Society of Ultrasound in Obstetrics and Gynecology     Volume:  11     ISSN:  0960-7692     ISO Abbreviation:  Ultrasound Obstet Gynecol     Publication Date:  1998 Jun 
Date Detail:
Created Date:  1998-10-06     Completed Date:  1998-10-06     Revised Date:  2007-11-15    
Medline Journal Info:
Nlm Unique ID:  9108340     Medline TA:  Ultrasound Obstet Gynecol     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  419-25     Citation Subset:  IM    
Department of Obstetrics and Gynecology, University Hospital of Bergen, Norway.
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MeSH Terms
Analysis of Variance
Blood Flow Velocity
Cross-Sectional Studies
Fetus / physiology*
Gestational Age
Hemodynamics / physiology
Observer Variation
Pregnancy / physiology*
Reference Values
Sensitivity and Specificity
Ultrasonography, Doppler, Pulsed
Ultrasonography, Prenatal / methods*
Umbilical Veins / anatomy & histology,  ultrasonography*
Vena Cava, Inferior / anatomy & histology,  ultrasonography*

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

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