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Ultrasound/Imaging

Poster Session 3

(781) Multiethnic Growth Standards for Fetal Body Composition and Organ Volumes Derived from 3D Ultrasonography

Wednesday, February 14, 2024
8:30 AM – 10:00 AM  
Location: Prince George's Exhibit Hall CDE, Lower Atrium Level
Objective: For three-dimensional (3D) ultrasound to live up to its potential to improve estimated fetal weight precision and characterize fetal growth abnormalities, it is first necessary to establish population-based standards for 3D measures including indicators of body composition (fractional limb volumes (arm [AVol], thigh [TVol])) and organ volumes. Growth in fat and lean mass and organ size may be differentially altered by nutritional, metabolic or environmental influences and in complicated pregnancies, in ways not identifiable using corresponding 2D measures. Our objective was to create standards for fetal 3D measures and compare with traditional 2D measures.

Study Design: The Fetal 3D Study included banked research-quality images of singletons from 12 U.S. sites, up to 5 scans per fetus, and was racially and ethnically diverse. All gravidas had low-risk profiles, and their neonates had normal outcomes (N=1,730). Volumes were measured by protocol and estimated, weighted curves (5th, 50th, 95th percentiles) derived from 15-41 wks using mixed models with cubic splines.

Results: Subcutaneous thickness of abdomen, arm, and thigh increased linearly, with slight acceleration around 27-29 wks. AVol, TVol, and lean limb volume increased along a quadratic curvature, with acceleration around 29-30 wks.(Fig A) In contrast, 2D humerus and femur lengths demonstrated a logarithmic shape, with fastest growth in the 2nd trimester.(Fig B) Cerebellar 2D diameter increased linearly, while cerebellar 3D volume growth gradually accelerated until 32 wks and then decelerated. Lung, kidney, and liver volumes all had gradual early growth followed by a linear acceleration beginning at 25 wks for lungs, 26-27 wks for kidneys, and 29 wks for liver.

Conclusion: Growth patterns and timing of maximal growth for 3D limb (lean and fat tissue) and organ volumes differed from traditional 2D growth measures. Multiethnic standards for 3D growth measures may complement 2D, particularly in the 3rd trimester. Future studies will investigate 3D as potential indicators of abnormal growth and association with adverse pregnancy outcomes.