PPT Slide
This is a uterus from a sow at 28 days post mating.
The uterus and its contents weighed 12 pounds. Most of this weight was fluid.
It is this fluid that is present in pregnant females that is detected by conventional A-mode pregnancy testing devices. Real time ultrasound ultrasound devices provide a 2 dimensional cross sectional view of the fluid filled uterine horns and the embryos as well.