Related Experiment Video
Updated: Jul 12, 2026
08:04
Murine Fetal Echocardiography
Published on: February 15, 2013
Menstrual age-dependent systematic error in sonographic fetal weight estimation: a mathematical model
1Department of Obstetrics and Gynecology, National University Hospital, Kent Ridge Road, Singapore 119074.
Journal of Clinical Ultrasound : JCU
|April 12, 2002
Summary
Computer modeling shows volumetric formulas offer the most consistent accuracy for estimating fetal weight across all stages of pregnancy. Other methods vary significantly with gestational age.
Area of Science:
- Obstetrics and Gynecology
- Medical Imaging
- Fetal Medicine
Background:
- Accurate fetal weight estimation is crucial for optimal pregnancy management.
- Sonographic formulas are widely used but their accuracy can vary with gestational age.
Purpose of the Study:
- To evaluate the accuracy of various sonographic formulas for fetal weight estimation.
- To compare formula performance across the full range of clinically significant menstrual ages using computer modeling.
Main Methods:
- Utilized computer modeling with British standards for sonographic biometric data.
- Assessed 10 different fetal weight estimation formulas.
- Compared simulated sonographic estimates against expected birth weights from 24 weeks' gestation to term.
Main Results:
- Formula accuracy varied significantly by menstrual age and formula type.
- Most formulas tended to overestimate fetal weight at term.
- Volumetric formulas (Combs's, Shinozuka's) demonstrated the least variation in accuracy across menstrual ages.
Conclusions:
- Sonographic fetal weight estimation using volumetric formulas provides more consistent accuracy throughout pregnancy compared to other methods.
- The choice of formula impacts accuracy, with volumetric approaches being more reliable across gestational ages.
More Related Videos
Related Concept Videos
01:52Regression Toward the Mean
Regression toward the mean (“RTM”) is a phenomenon in which extremely high or low values—for example, and individual’s blood pressure at a particular moment—appear closer to a group’s average upon remeasuring. Although this statistical peculiarity is the result of random error and chance, it has been problematic across various medical, scientific, financial and psychological applications. In particular, RTM, if not taken into account, can interfere when researchers try to extrapolate results...
03:37Uncertainty in Measurement: Accuracy and Precision
Scientists typically make repeated measurements of a quantity to ensure the quality of their findings and to evaluate both the precision and the accuracy of their results. Measurements are said to be precise if they yield very similar results when repeated in the same manner. A measurement is considered accurate if it yields a result that is very close to the true or the accepted value. Precise values agree with each other; accurate values agree with a true value.
01:20Random and Systematic Errors
Scientists always try their best to record measurements with the utmost accuracy and precision. However, sometimes errors do occur. These errors can be random or systematic. Random errors are observed due to the inconsistency or fluctuation in the measurement process, or variations in the quantity itself that is being measured. Such errors fluctuate from being greater than or less than the true value in repeated measurements. Consider a scientist measuring the length of an earthworm using a...
01:10Propagation of Uncertainty from Systematic Error
The atomic mass of an element varies due to the relative ratio of its isotopes. A sample's relative proportion of oxygen isotopes influences its average atomic mass. For instance, if we were to measure the atomic mass of oxygen from a sample, the mass would be a weighted average of the isotopic masses of oxygen in that sample. Since a single sample is not likely to perfectly reflect the true atomic mass of oxygen for all the molecules of oxygen on Earth, the mass we obtain from this particular...
01:23Mechanistic Models: Compartment Models in Individual and Population Analysis
Mechanistic models are utilized in individual analysis using single-source data, but imperfections arise due to data collection errors, preventing perfect prediction of observed data. The mathematical equation involves known values (Xi), observed concentrations (Ci), measurement errors (εi), model parameters (ϕj), and the related function (ƒi) for i number of values. Different least-squares metrics quantify differences between predicted and observed values. The ordinary least squares (OLS)...
01:30Typical Model Studies
Fluid mechanics model studies often utilize scaled-down systems to predict fluid behavior in full-scale environments, such as river flows, dam spillways, and structures interacting with open surfaces. Maintaining Froude number similarity in river models is crucial, as it replicates surface flow features like wave patterns and velocities.