Document Detail

Systematic labelling of twin pregnancies on ultrasound: limitations and guidance.
MedLine Citation:
PMID:  21400626     Owner:  NLM     Status:  Publisher    
INTRODUCTION: Correct labelling of twins is needed for consistency in applying and interpreting longitudinal scan and prenatal screening/diagnostic results. The aim of this study is to describe a standard method of twin labelling in the first trimester of pregnancy and to assess the robustness of such a technique in predicting the presenting twin in subsequent scans and at delivery. METHODOLOGY: This was a retrospective first trimester study performed on all twin pregnancies between 2000 and 2010. The fetus contained in the gestational sac closest to the maternal cervix was designated as twin one and the relative orientation of the fetuses to each other was then defined as either lateral (left/right) or vertical (top/bottom). In discordant sex twins, the sex and presenting order of the twins on the final scan prior to delivery was documented and compared to the sex and birth order at delivery. RESULTS: A total of 416 twin pregnancies were seen during the study period. At the 11-14 week scan 90.9% of twins were in lateral (left/right) orientation whilst the remainder were oriented in a vertical (top/bottom) orientation. None of the vertically oriented twin pairs and 32 (8.5%) of the laterally orientated twin pairs changed their presenting order between the first and the last ultrasound prior to delivery. There were 108 discordant sex twins scanned in the third trimester resulting in a change in twin birth order for 23.0% of Caesarean sections compared to 5.9% of those delivered vaginally. CONCLUSION: The study demonstrates that antenatal labelling of twins according to the laterality (left/right) or vertical orientation (top/bottom) is reliable and reproducible. The latter technique ensures continuity of biometric assessments from serial scans at each visit, and as such should be adopted as the preferred method of twin labelling. Furthermore, the use of orientation rather than number for antenatal labelling of twins precludes any misconception regarding which twin will be born first and ensures that parents and paediatricians are aware of the significant likelihood of a peripartum switch. Copyright © 2011 ISUOG. Published by John Wiley & Sons, Ltd.
Tiran Dias; Samantha Ladd; Samina Mahsud-Dornan; Amar Bhide; Aris T Papageorghiou; Basky Thilaganathan
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2011-3-11
Journal Detail:
Title:  Ultrasound in obstetrics & gynecology : the official journal of the International Society of Ultrasound in Obstetrics and Gynecology     Volume:  -     ISSN:  1469-0705     ISO Abbreviation:  -     Publication Date:  2011 Mar 
Date Detail:
Created Date:  2011-3-14     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9108340     Medline TA:  Ultrasound Obstet Gynecol     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Copyright Information:
Copyright © 2011 ISUOG. Published by John Wiley & Sons, Ltd.
Fetal Medicine Unit, Academic Department of Obstetrics and Gynaecology, St George's Hospital Medical School, London.
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