A Matter of Time

Abstract

Objective-To assess the average duration of detailed fetal anatomic surveys in pregnancy in relation to gestational age (GA) and the maternal body mass index (BMI) to determine optimal timing of the examination.Methods-This was a retrospective cohort study of gravidae presenting for detailed fetal anatomic examinations between January 1, 2010, and June 30, 2017. After excluding examinations expected to have longer duration (ie, multifetal, major fetal anomalies), there were a total of 6522 examinations performed between GAs of 18 weeks 0 days and 22 weeks 0 days. Women were grouped by BMI, and results were analyzed by logistic regression.Results-Gravidae of normal weight (BMI, 18.5-24.9 kg/m 2 ) had a decrease of 47.47 seconds of the examination time with each increasing week of gestation (P = .036). Overweight (BMI, 25-29.9 kg/m 2 ) gravidae similarly had a decrease of 66.31 seconds of the examination time with each additional week of gestation (P = .017). Underweight (BMI, 8.5 kg/m 2 ) and obese (BMI, ≥30 kg/m 2 ) gravidae did not have differences in the examination time with increasing GA. Increases in suboptimal examinations were noted with an increasing BMI (P < .001). There was a decreased frequency of suboptimal examinations in obese gravidae with a BMI of 40 kg/m 2 or higher with increasing GA (P = .037).Conclusions-The duration of detailed fetal anatomic examinations decreased with increasing GA in normal-weight and overweight gravidae but not in obese gravidae. Performing the anatomy scan earlier in class I and II obese gravidae (BMI, 30-40 kg/m 2 ) may enable improved pregnancy management options without increasing the examination duration or likelihood of a suboptimal evaluation.

Completion of Fetal Anatomy Evaluations in Women With Body Mass Index ≥ 50 kg/m2

“…Further follow‐up scans for missed anatomy can continue, often every 4 weeks for persistent missed anatomy. At 32 weeks, all patients with BMI ≥40 kg/m 2 undergo weekly antenatal testing with biophysical profiles, which affords sonographers and MFM physicians other opportunities to catch missed views if any remain 16 …”

“…At 32 weeks, all patients with BMI ≥40 kg/m 2 undergo weekly antenatal testing with biophysical profiles, which affords sonographers and MFM physicians other opportunities to catch missed views if any remain. 16 The primary outcome in this study was completion of all views at the first or at subsequent ultrasound scans, that is, whether the patient had all 24 views optimally captured. This outcome was first assessed at the initial ultrasound at 20-22 weeks, and then assessed throughout each index pregnancy to provide a final assessment of whether fetal anatomy was completely assessed prior to delivery.…”

“…The most common anomalies in obese women compared to nonobese women include neural tube and cardiac defects 9 . Achieving a complete scan often requires multiple scans 10 or creative techniques such as imaging laterally or inferiorly to the abdominal fat pad, 10 transvaginally for fetal structures close to the maternal cervix, 11,12 through the umbilicus with a transvaginal probe, 13 or at a nontraditional time in pregnancy 14–16 …”

“…9 Achieving a complete scan often requires multiple scans 10 or creative techniques such as imaging laterally or inferiorly to the abdominal fat pad, 10 transvaginally for fetal structures close to the maternal cervix, 11,12 through the umbilicus with a transvaginal probe, 13 or at a nontraditional time in pregnancy. [14][15][16] These problems are amplified with extreme obesity, and few studies specifically focus on women with BMI of 50 kg/m 2 or greater. This group has different fetal ultrasound outcomes compared to others with class III obesity (eg, BMI 40-49.9 kg/m 2 ) in cohorts where both strata are included.…”