Abstract
Introduction First-trimester ultrasound (US) for anatomy assessment may improve anomaly detection,
but it may also increase overall US utilization. We sought to assess the utility of
first-trimester US for evaluation of fetal anatomy.
Materials and Methods A decision analytic model was created to compare first- plus second-trimester anatomy
scans to second-trimester scan alone in four populations: general, normal weight women,
obese women, and diabetics. Probability estimates were obtained from the literature.
Outcomes considered were number of: major structural anomalies detected, US performed,
and false-positive US. Multivariable sensitivity analyses were performed to evaluate
the consistency of the model with varying assumptions.
Results A strategy of first- plus second-trimester US detected the highest number of anomalies
but required more US examinations per anomaly detected. The addition of a first-trimester
anatomy US was associated with a small increase in the false-positive US (< 10/10,000).
In populations with higher anomaly prevalence and lower second-trimester US sensitivity
(i.e., diabetes, obesity), the number of additional US performed per anomaly detected
with the first-trimester US was < 60.
Discussion In high-risk populations, a first-trimester US in addition to a second-trimester
US may be a beneficial approach to detecting anomalies.
Keywords
anatomy ultrasound - first trimester - second trimester - decision analysis - sensitivity
