"Roughly" may be the key here. As I've mentioned before, I was involved in a doe deer harvest survey which counted on hunters to bring in the uterus to check for fertilization. An illustrated pamphlet had been provided beforehand. Most of these hunters had field dressed deer before. Nevertheless, many mistakenly brought in the bladder, or at best, cut out a wedge that included the upper vagina and the bladder along with the uterus, much like what was done to Annie Chapman. A few did it right.
As mentioned before, an Ed Gein type person who has a peculiar fetish enough to research his proclivity, but not the skill to be consistent, can very well explain why the extraction of the uteri varried in the instances it was done... let alone the environment at the time. With only the one example at the time, it is easy to see why the conclusions were reached after the Chapman murder and something different applied after the murder and mutilations if Catherine Eddowes.
When evidence is not to be had, theories abound. Even the most plausible of them do not carry conviction- London Times Nov. 10.1888