OBJECTIVE: To review the literature concerning the efficacy of early ultrasonography (at 11–14 weeks of gestation) to identify fetal malformations.
DATA SOURCES: A search in PubMed, MEDLINE, Embase, Cochrane Library, and ClinicalTrials.gov was performed (January 2000 to December 2012). Keywords were: fetal anatomy, fetal echocardiography, nuchal translucency, fetal structural anomalies, fetal malformations, prenatal diagnosis, prenatal screening, and first-trimester ultrasonography.
METHODS OF STUDY SELECTION: Inclusion criteria were: fetal anatomy examination at early ultrasonography and diagnosis of fetal malformations confirmed by postnatal or postmortem examination. Data abstracted were: sample size, location of structural defect, ultrasound modality, presence of multiple defects, and study population. Pooled detection rate was calculated for each malformation and compared with χ2. Differences were considered statistically significant if P<.05.
TABULATION, INTEGRATION, AND RESULTS: From 1,203 articles, 19 were included. Overall, we pooled 78,002 fetuses undergoing ultrasonography at 11–14 weeks, of which 996 were malformed, leading to prevalence of malformation of 12 per 1,000. The overall detection rate was 472 of 957 (51%). The highest detection rate was achieved for neck anomalies (92%), whereas limbs (34%), face (34%), and genitourinary anomalies (34%) were associated with the lowest detection rate. At 14 weeks of gestation or less, fetal echocardiography detected 53% of congenital heart disease compared with 43% by complete scan (P=.040). The use of Doppler did not improve the detection rate for congenital heart defects (52% compared with 44%, respectively; P=.11). Multiple defects were identified more frequently than isolated malformations (60% compared with 44%; P=.005). The detection rate was higher combining transabdominal and transvaginal techniques (62%) than either abdominal (51%) or transvaginal (34%; P<.001). Detection rate was higher in women at high risk (65%) than unselected population (50% P=.001).
CONCLUSION: Because of the natural history of fetal defects and the late development of some organ systems, a number of fetal malformations remain undetected by early ultrasonography.