Repeat anatomic surveys performed for an initial incomplete study: the sonographer and physician factors

Abstract

Repeat obstetrical anatomic surveys are often performed because of incomplete initial studies despite conflicting evidence on their utility. To determine the frequency and yield of repeat obstetrical anatomic surveys performed because of incomplete initial studies and to determine patient and provider factors associated with the recommendation for a second study. A 10-year retrospective cohort study of women having an initial anatomic survey at 18 weeks to 21 weeks and 6/7 days of gestation at a single nonreferral county hospital. We identified the number of patients needed to scan to detect an anatomic abnormality for the overall cohort and for women having a repeat study. Select patient, sonographer, and reading physician factors were compared between the repeat-ultrasound and no-repeat-ultrasound groups by the 2-sample t test, chi-squared analysis, or analysis of variance, as appropriate. Multivariate logistic regression was used to assess the significance of multiple factors contributing to the recommendation for repeat ultrasounds. A total of 18,911 women had an initial anatomic survey between 18 weeks and 21 weeks and 6/7 days of gestation, and 2310 (12.2%) had a repeat ultrasound because of an incomplete initial study. For the overall cohort, there were 642 structural anomalies detected, with the number of patients needed to scan being 29. Among the 2310 repeat ultrasounds, only 7 structural anomalies were detected, whereas the number of patients needed to scan was 330, representing only 1.1% of all prenatally-identified anomalies. The frequency of recommended repeat ultrasounds varied by performing sonographer (4.5%-45.8%) and reading physician (7.1%-21.6%), both with P<.001 by 1-way analysis of variance. Clinical factors significantly impacting the odds of repeat ultrasounds included body mass index, gestational age, and previous cesarean delivery, but were less impactful than the sonographer and physician. The primary determinants of the perceived need for a repeat ultrasound are the sonographer and physician reader, with clinical factors having less but still significant importance. Repeat anatomic surveys account for a significant fraction of our total anatomic surveys and are of limited diagnostic utility. Recommendation of repeat anatomic surveys should be considered within the context of these findings.