Consensus Report on the 76811 Scan: Modification

A Matter of Time: Does Gestational Age Affect the Duration of the Fetal Anatomic Survey?

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/m² ) 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/m² ) 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/m² ) and obese (BMI, ≥30 kg/m² ) 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/m² 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/m² ) may enable improved pregnancy management options without increasing the examination duration or likelihood of a suboptimal evaluation.

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

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.