Oztekin 2009.

Study characteristics
Patient Sampling	Study design: retrospective observational study Recruitment: ultrasound screening was performed at 11 to 14 weeks in all pregnant women who attended the ultrasound unit during the study period Study start and end date: 2003 to 2007
Patient characteristics and setting	Setting: tertiary care facility (Bozyaka Training and Research Hospital) Region(s) and country/countries from which participants were recruited: Izmir, Turkey Sample size: 1041 Study eligibility criteria: all pregnant women undergoing first‐trimester ultrasound screening at the study centre were included Number of participants with the target condition: 18 Population type: unselected population Prior testing: nuchal translucency measurement at the time of the first‐trimester scan
Index tests	Type: two‐stage screening First‐trimester scan: Timing (weeks and days gestation): 11 to 14 weeks’ gestation Ultrasound scanning protocol: detailed Cardiac screening: extended Mode of examination: primary transabdominal, transvaginal if necessary Single or multiple operators: single Staff qualification and/or operator experience level: experienced radiologist, not further specified Second‐trimester scan: Timing: 18 to 22 weeks’ gestation Ultrasound scanning protocol: not reported Cardiac screening: not reported Mode of examination: not reported Single or multiple operators: not reported Staff qualification and/or operator experience level: not reported
Target condition and reference standard(s)	Target condition(s): major fetal structural anomalies Definitions used for major and minor congenital abnormalities: major was defined as lethal, incurable or curable severe abnormalities with a high risk of residual handicap. Less severe or benign abnormalities constituted the group of minor structural abnormalities. Reference standard (live birth): pregnancy and neonatal outcomes from hospital records, from contacting clinicians and from patients themselves Reference standard (fetal or neonatal demise): unclear; results mention whether suspected anomalies were confirmed in terminated pregnancies; methods for confirmation of the anomaly are not reported Postnatal follow‐up duration: not reported
Flow and timing	Eligible patients: 1085 Exclusions (study investigator): 41 lost to follow‐up (3.8%) Exclusions (review team): 3 (2 cases with isolated soft markers for chromosomal abnormalities, 1 case with a soft marker and an anomaly considered minor by the review team)
Comparative
Notes	Funding source: not reported
Methodological quality
Item	Authors' judgement	Risk of bias	Applicability concerns
DOMAIN 1: Patient Selection
Was a consecutive or random sample of patients enrolled?	Yes
Was a case‐control design avoided?	Yes
Did the study avoid inappropriate exclusions?	Yes
Could the selection of patients have introduced bias?		Low risk
Are there concerns that the included patients and setting do not match the review question?			High
DOMAIN 2: Index Test (First‐trimester scan)
Were the index test results interpreted without knowledge of the results of the reference standard?	Yes
If a threshold was used, was it pre‐specified?	Yes
Could the conduct or interpretation of the index test have introduced bias?		Low risk
Are there concerns that the index test, its conduct, or interpretation differ from the review question?			High
DOMAIN 2: Index Test (First + second‐trimester scan)
Were the index test results interpreted without knowledge of the results of the reference standard?	Yes
If a threshold was used, was it pre‐specified?	Yes
Could the conduct or interpretation of the index test have introduced bias?		Low risk
Are there concerns that the index test, its conduct, or interpretation differ from the review question?			Low concern
DOMAIN 2: Index Test (Single second‐trimester scan)
DOMAIN 3: Reference Standard
Is the reference standard likely to correctly classify anomalies that are externally visible, present with clinically relevant symptoms shortly after birth, or that are considered to be lethal/incompatible with life?	Yes
Is the reference standard likely to correctly classify anomalies that may present after discharge from postnatal care?	Unclear
Were the reference standard results interpreted without knowledge of the results of the index test?	No
Could the reference standard, its conduct, or its interpretation have introduced bias?		Unclear risk
Are there concerns that the target condition as defined by the reference standard does not match the question?			Low concern
DOMAIN 4: Flow and Timing
Did all live‐born infants receive a reference standard?	Yes
Did all live‐born infants receive the same reference standard?	No
Did all cases of fetal or perinatal loss receive the reference standard (including termination of pregnancy, intra‐uterine death, stillbirth, perinatal mortality)?	Unclear
Were all patients included in the analysis?	Yes
Could the patient flow have introduced bias?		Unclear risk