Normal Fetal Growth Profile at 10-41 Weeks of Gestation - An Update Based on 10225 Normal Singleton Pregnancies and Measurement of the Fetal Parameters Using 3D Ultrasound.

OBJECTIVE: To construct new growth charts and tables for the following fetal growth parameters: biparietal diameter (BPD), occipitofrontal diameter (OFD), head circumference (HC), abdominal transverse diameter (ATD), abdominal sagittal diameter (ASD), abdominal circumference (AC), femur length (Fe), tibia length (Ti), fibula length (Fi), humerus length (Hu), radius length (Ra), and ulna length (Ul). PATIENTS AND METHODS: This prospective study was conducted at a level III ultrasound center as a population-based cross-sectional study on 10 225 normal singleton pregnancies with a gestational age between 10 and 41 completed weeks. Gestational age was confirmed in all cases by an ultrasound examination with crown-rump measurement before 10 weeks of gestation. All examinations were performed with 3 D probes. BPD, OFD, ATD, and ASD were measured as outer-to-outer measurements (skin-to-skin) after identifying the exact biometric planes by 3 D multiplanar display. HC was computed using the formula . For AC the approximate elliptical formula AC = (ATD+ASD)/2 × 3.142 was used. Measurements of the limb bones included the entire ossified shaft. RESULTS: Based on a nonlinear regression model for the age-specific mean values, distribution-free reference ranges were calculated for the parameters BPD, OFD, HC, ATD, ASD, AC, Fe, Ti, Fi, Hu, Ra and Ul. The new reference ranges were compared with our reference ranges published in 1996 as well as with different reference charts published by other authors. CONCLUSION: 3 D ultrasound allows a controlled demonstration of all fetal planes required for exact biometric measurements. The fetal growth profile including the 12 biometric parameters gives a precise overview of normal or abnormal fetal growth.

3-Dimensional Ultrasound: How can the Fetal Corpus Callosum Be Demonstrated Correctly?

The aim of this article is to outline the correct demonstration of the fetal corpus callosum with 3D ultrasound between 18 and 40 weeks of gestation. An abdominal or transvaginal 3D transducer can be used for acquisition of the fetal brain depending on the position of the fetus. The best demonstration of the corpus callosum can be achieved, when the volume with the corpus callosum is acquired from a sagittal or parasagittal sectional plane of the brain. Once the volume is stored in the memory, the multiplanar mode allows manipulation in all three dimensions until the exact median plane is seen, showing the corpus callosum as a hypo- or anechoic curved structure. Volume acquisition of the brain from an axial plane of the fetal head - typically used for biometrical measurements of the head diameters - is not recommended for clinical evaluation of the corpus callosum because the reconstructed median plane does not reveal the margins and the structure of the corpus callosum precisely. Other display modes such as volume contrast imaging (VCI), OmniView-VCI, and tomographic display may also be used for demonstration of the corpus callosum. However, these display modes only provide the operator with good image quality of the corpus callosum if the fetal brain was acquired from a sagittal and not from an axial plane. CONCLUSION: 3D ultrasound is an excellent clinical tool for the exact presentation of the fetal corpus callosum because it allows volume manipulation of the fetal head in all three dimensions with precise demonstration of the median plane of the brain.

Advantages of 3D ultrasound in the assessment of fetal abnormalities.

Three-/four-dimensional (3D/4D) imaging enables a more detailed survey of the embryo and the fetus compared to two-dimensional (2D) ultrasound. The availability of several display modes and standardized examinations permits the demonstration of both the normal and abnormal fetal anatomy in controlled planes and rendered images from different angles. This allows the demonstration of even subtle fetal defects in an ideal sectional plane in a precisely rendered surface or transparent image viewed from an optimal angle. When counseling the parents, the rendered images can help them understand the severity of an existing malformation or, conversely, ensure them of the absence of any fetal abnormality. This is particularly useful in cases with an increased recurrence risk of a specific fetal malformation.