Ultrasound Obstet Gynecol 2023:61:127-143Published online in Wiley Online Library (wileyonlinelibrary.com).DOI:10.1002/uog.261069isuogGUIDELINESISUOG Practice Guidelines(updated):performance of11-14-week ultrasound scanClinical Standards Committeefacilitate delivery of optimized antenatal care,ensuringthe best possible outcomes for mother and fetus.InThe International Society of Ultrasound in Obstetricsearly pregnancy,it is important to confirm viability,and Gynecology (ISUOG)is a scientific organizationestablish gestational age accurately,determine the numberthat encourages sound clinical practice and high-qualityof fetuses and,in the presence of a multiple pregnancy,teaching and research related to diagnostic imagingassess chorionicity and amnionicity.Towards the end ofin women's healthcare.The ISUOG Clinical Standardsthe first trimester,the scan also offers an opportunity toCommittee (CSC)has a remit to develop Practicedetect major fetal abnormalities and,in healthcare systemsGuidelines and Consensus Statements as educationalthat offer first-trimester aneuploidy screening,to measurerecommendations that provide healthcare practitionersthe nuchal translucency (NT)thickness.However,manywith a consensus-based approach,from experts,formajor malformations may develop later in pregnancy ordiagnostic imaging.They are intended to reflect whatmay not be detected even with appropriate equipment andis considered by ISUOG to be the best practice at the timein the most experienced of hands.at which they are issued.Although ISUOG has made everyeffort to ensure that Guidelines are accurate when issued,neither the Society nor any of its employees or membersWhen should a first-trimester ultrasound scan beaccepts liability for the consequences of any inaccurate orperformed?misleading data,opinions or statements issued by the CSC.If an earlier first-trimester ultrasound scan has not beenThe ISUOG CSC documents are not intended to establishdone,it is advisable to offer the first scan when gestationala legal standard of care,because interpretation of theevidence that underpins the Guidelines may be influencedage is estimated to be between 11+0 and 14+0weeks'by individual circumstances,local protocol and availablegestation,as this provides an opportunity to achieveresources.Approved Guidelines can be distributed freelythe aforementioned aims,i.e.confirm viability,establishwith the permission of ISUOG (info@isuog.org).gestational age accurately,determine the number of viablefetuses and,if requested,evaluate fetal anatomy and riskof aneuploidy-18.Before starting the examination,aINTRODUCTIONhealthcare provider should counsel the woman/coupleregarding the potential benefits and limitations ofPerforming a routine first-trimester ultrasound exami-the first-trimester ultrasound scan (GOOD PRACTICEnation at 11+0 to 14+0 weeks'gestation is of valuePOINT).for confirming viability and plurality,accurate preg-nancy dating,screening for aneuploidies,identificationof major struc
