Detailed Fetal Anatomic Ultrasound Examination Duration and Association With Body Mass Index

Abstract

OBJECTIVE: To evaluate the association of the duration of the detailed fetal anatomic ultrasound examination with maternal body mass. METHODS: This was a retrospective chart review of patients presenting to our clinic for detailed fetal anatomic examinations between January 1, 2010, and June 30, 2017. After excluding multifetal pregnancies and other examinations expected to have a longer duration, a total of 6,522 examinations were performed between 18 0/7 and 22 0/7 weeks of gestation. Results were analyzed using analysis of variance and Student's t-test. RESULTS: Mean (SD) body mass index (BMI) was 29.3 (±7.7), and mean examination time was 51.5 (±10.4) minutes. We found that mean examination time was 48.8 (±9.6) minutes for patients with normal BMIs, 50.6 (±10.0) minutes for overweight patients, 52.2 (±10.4) minutes for patients with class I obesity, 54.6 (±10.3) minutes for patients with class II obesity, and 57.7 (±10.3) minutes for patients with class III obesity (P<.001). The duration of the detailed fetal anatomic ultrasound examination increased continuously with BMI (r=0.285, P<.001). CONCLUSION: We found that the duration of detailed fetal anatomic examinations increased with BMI. Examinations for gravid patients with class III obesity lasted 8.9 minutes longer than those for gravid patients with normal BMIs; examinations for gravid patients with BMIs of 50 or higher lasted 13.5 minutes longer. This information may be useful for fetal ultrasound examination scheduling.

A Matter of Time

“…A prior analysis of these data showed that there is a positive relationship between the detailed fetal anatomic examination duration and a rising maternal BMI. 17 This finding is similar to prior studies suggesting that obesity was associated with increased time needed to complete a first-trimester screen 14,15 and contrasts with the findings of Romary et al, 35 which did not show these differences in the examination duration between gravidae of various BMIs for either a firstor second-trimester ultrasound examination.…”

“…The frequency of suboptimal examinations was shown to increase with higher maternal prepregnancy BMI classes, consistent with prior studies. [8][9][10][15][16][17][18][25][26][27][28][29][30][31][32][33] Although not explored in Values in parentheses are 95% confidence intervals. this study, prior approaches to combat this issue have suggested that an earlier scan in addition to the standard 20-week anomaly scan has higher completion rates in obese women at the cost of increased resource use.…”

“…This study was a secondary analysis of data obtained at the Center for Perinatal Care at the University of Wisconsin-Madison as part of the previously published study by Gupta et al 17 in 2019. The parent study and this secondary analysis were both approved by the Institutional Review Board at the UnityPoint Health-Meriter Hospital (Meriter Institutional Review Board number 2017-012).…”

“…13 Obesity has also been shown to increase the time required to complete ultrasound examinations for fetal anomaly screens and first-trimester aneuploidy risk assessment. [14][15][16][17] Obese women are also more likely to require repeated examinations to complete the fetal anatomic survey. 18 It has been suggested that delaying the ultrasound examination in obese gravidae to 20 to 22 weeks may improve visualization of anatomy.…”

Accuracy and Completion Rate of the Fetal Anatomic Survey in the Super Obese Parturient

“…Sonography in the super obese population can be difficult, as the amplitude diminishes as sound propagates through the body, making images hard to obtain and interpret. In a recent retrospective study, the anatomic survey in patients with super obesity took 13.5 minutes longer than patients with normal BMI 7 . Multiple prior studies have found that as BMI increases, the completion rate of the anatomic survey decreases and the number of studies required to complete the evaluation increases 8‐10 .…”