Document Detail


First-trimester ultrasound dating of twin pregnancy: are singleton charts reliable?
MedLine Citation:
PMID:  20482534     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
OBJECTIVE: The aim of this study was to assess the performance of validated singleton crown-rump length (CRL) formulae in dating twin pregnancies at 11-14 weeks of gestation. DESIGN: Retrospective cohort study. SETTING: Fetal medicine unit of a London teaching hospital. SAMPLE: Three hundred and eighty-four pregnancies with known dates of conception. METHODS: Retrospective analysis of 266 singletons and 118 twin pregnancies conceived by in vitro fertilisation (IVF), with a known date of conception. The gestation calculated from the date of conception was compared with the expected gestation from fetal size using a number of different CRL formulae. MAIN OUTCOME MEASURES: Difference in gestational age computed from fetal size (CRL) of the bigger and smaller fetus in twin pregnancies and singleton pregnancies using three formulae. RESULTS: Two of the three studied CRL formulae systematically underestimated the mean gestational age and size of singleton IVF pregnancies (Robinson formula: gestation = 1.4 days, size = 2.7 mm). Twin CRL measurements straddled those of singletons, regardless of the CRL formula used (Robinson formula: larger twin gestation = 2.4 days, size = 4.7 mm; smaller twin gestation = 0.8 days, size = 1.7 mm). These underestimates in gestation and size for IVF singleton and twin pregnancies are well within the known limits of accuracy of first = trimester ultrasound measurements, and are of limited clinical significance. CONCLUSIONS: Currently available CRL charts underestimate both the age and size of IVF singleton pregnancies by a clinically insignificant amount. This difference is similar for twin pregnancies, suggesting that singleton CRL charts can be used to date twin pregnancies accurately.
Authors:
T Dias; S Mahsud-Dornan; B Thilaganathan; A Papageorghiou; A Bhide
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Publication Detail:
Type:  Journal Article     Date:  2010-05-19
Journal Detail:
Title:  BJOG : an international journal of obstetrics and gynaecology     Volume:  117     ISSN:  1471-0528     ISO Abbreviation:  BJOG     Publication Date:  2010 Jul 
Date Detail:
Created Date:  2010-06-11     Completed Date:  2010-09-21     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  100935741     Medline TA:  BJOG     Country:  England    
Other Details:
Languages:  eng     Pagination:  979-84     Citation Subset:  AIM; IM    
Affiliation:
Fetal Medicine Unit, Academic Department of Obstetrics and Gynaecology, St George's Hospital Medical School, London, UK.
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MeSH Terms
Descriptor/Qualifier:
Case-Control Studies
Crown-Rump Length*
Female
Fertilization in Vitro
Fetal Development / physiology*
Gestational Age
Humans
Pregnancy
Pregnancy Trimester, First
Pregnancy, Multiple / physiology*
Reference Values
Retrospective Studies
Twins
Ultrasonography, Prenatal / methods*

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


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