Thoracoabdominal structures

Thoracoabdominal structures. Prior to 12.5 DPC, the fetal thorax could not be differentiated from the abdomen. This distinction became apparent at 12.5 DPC, and the echogenic lungs grew increasingly distinct from the more hypoechoic liver over the remaining course of gestation. The fetal stomach and urinary bladder were not discreetly identifiable until 17.5 DPC, when they appeared as hypoechoic structures (Figure 13).

Conclusion

It is possible that the anesthesia chosen for these types of studies could affect the growth or development (or both) of the fetus. This drawback was addressed for this report by designating 3 groups of dams, each of which underwent only 4 imaging sessions during the last half of gestation. Isoflurane was selected because of its rapid induction and recovery properties and because it is commonly used in veterinary cesarean sections. Toxicology studies investigating chronic daily exposure (4 h daily at no more than 0.6%) before and during pregnancy reported a negative effect on development at the 0.6% level.

Discussion - part 3

Power Doppler, also known as amplitude-mode Doppler, disregards directional information and codes blood flow according to the number of moving reflectors (red blood cells) in the field. The higher the number of moving red cells (blood flow), the higher the brightness value of the Doppler display. It is frequency-independent and has higher sensitivity to low velocity blood flow than does conventional Doppler. Conventional color Doppler imaging with the 15-MHz system therefore can be used to provide information on the direction of flow, and both the color Doppler and power Doppler applications allow for pulsed-wave quantification of velocity as well as comparative indices of systolic and diastolic flow.