Gireada 2022.

Study characteristics
Patient Sampling	Study design: retrospective observational study Recruitment: hospital records of unselected consecutive patients attending the study centre for a routine anomaly scan during the study period were reviewed Study start and end date: 2019 to 2021
Patient characteristics and setting	Setting: private setting Region(s) and country/countries from which participants were recruited: Romania Sample size: 1597 Study eligibility criteria: pregnant women presenting for a routine fetal anomaly scan, with a known pregnancy outcome, who were scanned in the second or third trimester of pregnancy, or who were only scanned in the first trimester due to early termination of pregnancy Number of participants with the target condition: 36 Population type: unselected population Prior testing: not reported
Index tests	Type: two‐stage screening First‐trimester scan: Timing (weeks and days gestation): 11 to 13 weeks and 6 days of gestation Ultrasound scanning protocol: detailed Cardiac screening: extended Mode of examination: primary transabdominal, transvaginal if necessary Single or multiple operators: multiple (3) Staff qualification and/or operator experience level: specifically trained, not further specified Second‐trimester scan: Timing: 20 to 24 weeks’ gestation Ultrasound scanning protocol: detailed Cardiac screening: extended Mode of examination: transabdominal and transvaginal Single or multiple operators: multiple (3) Staff qualification and/or operator experience level: specifically trained, not further specified
Target condition and reference standard(s)	Target condition(s): cardiac anomalies (any type) Definitions used for major and minor congenital abnormalities: cardiac anomalies were considered major if they could require immediate care after birth Reference standard (live birth): all live‐born babies were examined by the neonatologist in the first 3 days of life Reference standard (fetal or neonatal demise): confirmed by transvaginal ultrasound (first trimester termination), confirmed by autopsy (second trimester termination) Postnatal follow‐up duration: 1 month after birth
Flow and timing	Eligible patients: 1608 Exclusions (study investigator): none reported Exclusions (review team): 11 (2 anomalies considered not detectable by prenatal ultrasound, 9 anomalies considered normal variants)
Comparative
Notes	Funding source: the authors declared that this research received no external funding
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?			Unclear
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?			Low concern
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?	Yes
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?		Low 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)?	No
Were all patients included in the analysis?	Yes
Could the patient flow have introduced bias?		High risk