Optimal timing of the second trimester fetal ultrasound in the obese gravida
Creators: name: Weatherborn, Megan
name: McGuinness, Bailey
name: Ogamba, Maureen Ifeoma
name: Leung, Katherine
name: Leftwich, Heidi K.
Publisher: name: Taylor & Francis
Year: 2020
Subjects: subject: Space Science
subject: Medicine
subject: Cell Biology
subject: 59999 Environmental Sciences not elsewhere classified
subject: FOS: Earth and related environmental sciences
subject: Sociology
subject: FOS: Sociology
subject: Immunology
subject: FOS: Clinical medicine
subject: 69999 Biological Sciences not elsewhere classified
subject: FOS: Biological sciences
subject: Developmental Biology
subject: Science Policy

description: Obesity is increasingly prevalent in the obstetric patient population, becoming one of the most commonly occurring risk factors in obstetric practice. Obesity has implications for maternal and fetal morbidity; in fact, some data suggest it is associated with higher rates of fetal anomaly. Coincident with this, maternal obesity poses an inherent challenge for ultrasound quality. The objective of this study is to investigate the relationship between ultrasound completion rates and advancing gestational age in obese gravidas, and to help identify an ideal gestational age to perform the second trimester ultrasound for fetal evaluation in the obese patient population. We hypothesized that in the obese patient, the odds of a completed scan would increase with each gestational age week, as fetal size increases. This is a retrospective cohort study at a single tertiary care center. Inclusion criteria were pregnant women with BMI greater than 30 who had second trimester fetal ultrasound and delivery at our institution. Exclusion criteria were pregnancies without documented BMI, ultrasound not performed between 18 0/6 and 21 6/7 weeks, multiple gestations, or ultrasound performed for indication other than fetal anatomic assessment. Ultrasound reports were considered incomplete if they indicated suboptimal or non-visualization of any anatomic structures included in the comprehensive anatomic survey. Demographic data was compared using Student’s t test and chi-square analysis where appropriate. Chi-square analysis was used to compare rates of completed surveys. <i>p</i> After application of eligibility criteria, our cohort included 1,954 subjects. When comparing subjects with a completed scan to those with an incomplete scan, there were more white subjects in the incomplete group (<i>p</i> = .012), but other analyzed demographics were similar between groups. When using 18 weeks as a referent group, with each additional completed week of gestation, subjects were more likely to have a completed scan, at 19 weeks (OR 1.29, CI 1.05–1.58); at 20 weeks (OR 1.46, CI 1.1–1.95); at 21 weeks (OR 2.12, CI 1.42–3.17) (<i>p</i> In this cohort of obese gravidas, the odds of having a completed anatomic survey continued to improve until 21 weeks gestational age. When comparing completed scans between each week, 18 weeks demonstrated consistently lower odds of a complete scan, however 20 weeks did not differ significantly from 19 weeks. Therefore, consideration should be made to perform the initial second trimester ultrasound for fetal evaluation in obese patients at 19 weeks gestational age to optimize completion rates while minimizing scans performed at advancing gestational ages.